REESE  LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

r/  BIOLOGY 

LIBRARY 
G 


THE  LAWS  OF  HEREDITY 


THE 
LAWS  OF   HEREDITY 

BY 
G.  ARCHDALL  REID 

M.B.,  F.R.S.E. 


WITH  A 

DIAGRAMMATIC   REPRESENTATION 

BY 

HERBERT  HALL  TURNER 

SAVILIAN   PROFESSOR   OF  ASTRONOMY,   OXFORD 


NEW  YORK 

THE  MAGMILLAN  COMPANY 
1910 


BIOLOGY 

LIBRARY 

G 


TO    THE 

MEMORY 

'       OF 

THOMAS  HENRY  HUXLEY 

A    GREAT    EXPONENT    OF   SCIENTIFIC    METHOD 


208108 


PREFACE 

THE  present  volume  covers    a    wider  area   than  my  last : 
The  Principles  of  Heredity.     No  problems  can  be  named 
of  greater  importance  to  the   community  than   those  of 
Heredity.     I  have  tried,  therefore,  to  make  the  argument  as  plain 
as  possible  to  the  general  reader.     And,  since  facts  which  we  are 
able  to  observe  and  verify  for  ourselves,  are  more  impressive  and 
valuable   intellectually  than  those  we   are  obliged   to   accept  at 
second  hand,   I   have  used,  whenever   possible,    material  that  is 
familiar  to  every  one. 

Some  biologists  may  regard  Chapter  III.,  which  deals  with 
scientific  method,  as  unnecessary  and  even  as  impertinent.  But 
every  writer  hopes  to  gain  wide  assent  to  his  reasoning ;  and, 
there  are,  apparently,  amongst  thinkers  about  living  beings,  such 
fundamental  differences  of  opinion  as  to  what  constitutes  evidence, 
what  logical  proof,  and  what  science,  that  no  one  can  hope  to 
secure  wide  assent  unless  he  first  lay  down  the  principles  that 
have  guided  his  own  thinking  and  obtains  assent  to  them.  If 
the  history  of  biology  be  considered,  I  believe  it  will  be  seen 
that  many  of  the  controversies,  in  which  its  students  have  en- 
gaged, arose  and  persisted  merely  because  the  disputants,  holding 
what  were  really  divergent  views  as  to  the  nature  of  science,  failed 
to  reach  a  preliminary  agreement  with  respect  to  their  basic 
assumptions.  As  far  as  my  powers  permitted,  I  have  followed  the 
rules  of  procedure  that  have  been  enunciated  by  every  authority 
who  has  both  thought  and  written  about  the  subject.  When  these 
rules  have  been  disregarded,  the  writers,  however  right  they  may 
be  able  to  prove  themselves  ultimately,  have  never  expressed  their 
dissent  in  reasoned  statements ;  they  have  merely  implied  it  in 
their  methods  of  work. 

If,  then,  the  reader  disagrees  with  commonly  accepted  opinions, 
if,  for  example,  he  especially  values  evidence  not  solely  because 
it  is  authentic  and  relevant  but  because  it  has  been  gathered  in 
some  particular  way,  or  if  he  thinks  that  we  should  not  use  all  the 


viii  THE  LAWS  OF  HEREDITY 

authentic  evidence  available,  or  that  facts  newly  asserted  are 
of  greater  value  than  truths  long  familiar  and  disputed  by  no  one, 
or  that  it  is  beneath  the  dignity  or  not  within  the  mission  of 
science  to  furnish  proof,  or  that  knowledge  derived  from  a  simple 
enumeration  of  instances  is  superior  to  knowledge  which  is 
founded  on  a  discovery  of  causes,  or  that  we  should  found 
hypotheses  on  the  exception  rather  than  the  rule,  or  that  it  is 
right  to  uphold  contradictories,  if  in  short  he  has  individual  and 
original  views  as  to  what  constitutes  proof  and  what  science,  then 
I  hope  he  will  endeavour  to  formulate  his  reasons  clearly.  Unless 
he  does  so,  his  opinions,  no  matter  how  correct  they  may  be,  are 
apt  to  bear  the  appearance  of  prejudices. 

Professor  H.  H.  Turner  has  contributed  an  Appendix  in  which 
some  of  the  main  arguments  of  the  text  are  thrown  into  diagram- 
matic form.  No  part  of  the  work  is  likely  to  prove  so  interesting 
and  convincing  as  this  Appendix.  I  have,  besides,  to  record  my 
great  indebtedness  to  him  for  much  very  valuable  advice. 

It  is  impossible  to  express  adequately  my  deep  sense  of  obliga- 
tion to  Dr  H.  B.  Donkin.  Not  only  has  he  been  a  sort  of  reference 
library,  but  he  has  read  and  re-read  the  whole  of  the  rough  and 
the  more  finished  manuscript,  and  the  former  has  grown  into  the 
latter  largely  under  his  guidance. 

Other  helpers,  whom  I  take  this  opportunity  of  thanking  most 
heartily,  are  Miss  J.  Ritter,  Mr  A.  D.  Darbishire,  Mr.  P.  C.  Glubb, 
and  Mr  D.  Waudby. 

While  writing  the  volume,  I  have  received  great  kindness  and 
encouragement  from  Dr  Alfred  Russel  Wallace,  Sir  William 
Thiselton-Dyer,  and  Sir  E.  Ray  Lankester. 

SOUTHSEA,  April  1910 


CONTENTS 

CHAPTER  I 


PAGE 

THE  CHARACTERS  OF  LIVING  BEINGS        .  I 


CHAPTER  II 

THE   METHOD  OF  DEVELOPMENT  ...  21 

CHAPTER  III 

THE  METHOD  OF  SCIENCE  .....  30 

CHAPTER  IV 

THE  LAMARCKIAN  DOCTRINE  ......  56 

CHAPTER  V 

VARIABILITY  ........  78 

CHAPTER  VI 

RETROGRESSION         .  .  .  ...  .  .  .  IO/ 

CHAPTER  VII 

MENDEL'S  LAWS         .......  142 

CHAPTER  VIII 

THE  MUTATION  THEORY      .  .  .  .  .  .  .169 

CHAPTER  IX 

THE  FUNCTION   OF  SEX        .  .  .  .  .  .  .187 

CHAPTER  X 

SUMMARY        .........  206 

ix 


x  THE  LAWS  OF  HEREDITY 

CHAPTER  XI 

HUMAN   DISEASES     ...... 

CHAPTER  XII 

ACQUIRED   IMMUNITY  .  ... 

CHAPTER  XIII 

THE  PRESENT  EVOLUTION  OF  MAN 

CHAPTER  XIV 

EPIDEMIC  AND   ENDEMIC  DISEASE 

CHAPTER  XV 

ALCOHOL        ....... 

CHAPTER  XVI 

THE  EVOLUTION   AGAINST   NARCOTICS       . 

CHAPTER  XVII 

IDEALISM   AND   COMMON   SENSE      . 

CHAPTER  XVIII 

NECESSARY  TRUTH  ..... 

CHAPTER  XIX 

THE   RELATION   OF  MIND  TO   BODY 

CHAPTER  XX 

REFLEX  ACTION,   INSTINCT,   AND   REASON 

CHAPTER  XXI 

THE  EVOLUTION   OF   MEMORY 


CONTENTS  xi 


CHAPTER  XXII 

PAGE 

NATURE  AND   NURTURE      .....  .  410 


CHAPTER  XXIII 

PHYSICAL  DETERIORATION   AND  MICROBIC  DISEASE        .  .           436 

CHAPTER  XXIV 

INTEMPERANCE  AND  INSANITY       ....  .          456 

CHAPTER  XXV 
EDUCATION  .........       477 

APPENDIX    .  517 

GLOSSARY     .           .                                            .  -        535 

INDEX          ...                      ...  .        539 


With  Earth's  first  Clay  They  did  the  Last  Man  knead, 
And  there  of  the  Last  Harvest  sow'd  the  Seed : 

And  the  first  Morning  of  Creation  wrote 
What  the  Last  Dawn  of  Reckoning  shall  read. 


THE    LAWS    OF   HEREDITY 

CHAPTER   I 
THE  CHARACTERS  OF  LIVING  BEINGS 

The  cell — Conjugation  of  cells — The  germ-plasm — Hereditary  tendencies 
or  potentialities — The  stimuli  under  which  living  beings  develop — Nutriment, 
injury,  use,  etc. — The  evolution  of  useful  reactions  to  stimuli — Almost  all 
living  structures  are  capable  to  some  extent  of  repairing  injuries,  but  not  nearly 
all  are  capable  of  growing  under  the  stimulus  of  use — The  real  meaning  of 
the  terms  inborn,  acquired,  and  inheritable — The  confusion  and  waste  of  labour 
which  has  resulted  from  a  use  of  inaccurate  and  misleading  terms. 


T 


I.  ^  |  ^\HE  material  basis  of  all  known  life  is  the  living  'cell.'  A 
cell  is  a  mass,  usually  very  minute,  of  a  jelly-like  sub- 
stance known  as  protoplasm.  The  lowest  plants  and 
animals  are  single  cells.  Higher  living  beings  are  compounded  of 
two  or  more,  it  may  be  billions  of  cells,  most  of  which  are  adherent 
together,  though  some — for  example,  the  blood-cells — may  move 
freely  within  the  organism.  Cells  multiply  by  self-division,  the 
mother-cell  distributing  itself  between  the  daughter-cells.  In  the 
case  of  unicellular  or  single  -  cell  organisms  the  daughter-cells 
separate,  but  in  higher  types  they  remain  together.  As  a  conse- 
quence a  man,  for  example,  is  an  organised  colony  or  community, 
a  family  or  tribe  or  race  of  cells,  all  of  which  have  descended  from 
a  common  cell-ancestor,  the  fertilized  ovum  or  egg.  Speaking  in 
general  terms,  the  descendants  of  a  unicellular  organism  closely 
resemble  their  ancestor.  Each  individual  is  able  to  continue  the 
species  by  self-division,  and  each  performs  all  the  functions  neces- 
sary to  existence,  such  as  the  procurement  of  food.  But  the 
descendants  of  the  fertilized  ovum,  though  they  remain  together, 
indeed  because  they  remain  together,  break  up  into  many  types. 
Thus,  in  a  man  there  are  skin-cells,  bone-cells,  nerve-cells,  various 
kinds  of  gland-cells,  and  others.  In  other  words,  the  members  of 
this  community  are  specialized  in  form  and  function.  Each  has  a 
special  shape  and  structure  whereby  it  is  adapted  to  perform  some 
i  i 


2  THE  CHARACTERS  OF  LIVING  BEINGS 

particular  duty.  None  are  fitted  to  perform  all  the  functions  of 
life,  and  none,  therefore,  can  long  maintain  a  separate  existence. 
Thus  a  skin  or  muscle  cell  parted  from  the  rest  of  the  community 
quickly  perishes.  Even  the  duty  of  continuing  the  race  is  dele- 
gated to  a  particular  set  of  cells,  the  germ-cells,  which  do  not 
otherwise  share  in  the  labours  of  the  community. 

2.  Germ-cells  derived  from  a  female  body  (e.g.  a  woman)  are 
termed  ova ;  whereas  those  derived  from  a  male  body  are  termed 
sperms.    Sperms  and  ova  differ  in  appearance,  but  we  have  no  reason 
to  suppose  that  they  are  not  equivalent  as  *  bearers  of  heredity.' 
They  are  not  male  and  female  ;  only  the  bodies,  the  cell-communi- 
ties which  they  inhabit,  are  male  and  female.     A  sperm  from  a 
male  body  unites  with  an  ovum  from  a  female  body.     The  single 
cell  thus  formed  is  termed  the  fertilized  ovum.    The  fertilized  ovum, 
dividing  and  redividing  many  times,  builds  up,  by  means  of  the 
descendants  thus  arising,  a  new  cell-community,  a  new  '  organism,' 
a  new  body,  a  new  '  individual,'  a  human  being,  for  instance. 

3.  That  fertilization  must  precede  reproduction  is  a  rule  almost 
universal    amongst    multicellular    species.      Without  fertilization 
their  ova  and  sperms  perish,  leaving  no  descendants.    But  fertiliza- 
tion is  not  quite  universal.     Some  species  consist  only  of  females. 
They   are   parthenogenetic,    that   is,   the   virgin  females  produce 
offspring.      Without    union   with    another    germ-cell,   the   ovum 
becomes  the  ancestor  of  a  new  cell-community.     More  common, 
especially  in  the  vegetable  kingdom,  is  self-fertilization.     Here  the 
individual  is  both  male  and  female  (hermaphrodite)  and  produces 
both  sperms  (pollen  grains)  and  ova  (ovules),  which  unite  with  one 
another.     But  cross-fertilization  is  by  far  the  most  common.     It 
is  secured  in  most  animals  by  the  device  of  sex,  in  plants  more 
commonly  by  the  ripening  at  different  periods  of  the  sperms  and 
ova  of  the  same  plant,  or  by  other  devices.     Neither  cross-  nor 
self-fertilization,  then,  is  necessary  to  reproduction.     But  the  fact 
that  fertilization,  especially  cross-fertilization,  the  mingling  of  the 
qualities  of  two  separate  cell-communities  to  secure  which  nature 
has  evolved  sex,  is  so  widespread  is  evidence  that  it  must  possess 
some  very  important  function,  some  very  important  advantage. 
Darwin  found  that  plants,  which  normally  reproduced  by  crossing, 
gave  origin  to  weakly  offspring  if  artificially  self-fertilized.     It  was 
argued,  consequently,  that  the  function  of  cross-fertilization  was  to 
invigorate   or    rejuvenate.      But  animals    and    plants    which   are 
parthenogenetic,  or  which  normally  fertilize  their  own  ovules,  are 
vigorous.      Clearly,  then,  though  crossing  is  necessary  to  the  well- 


THE  GERM-PLASM  3 

being  of  species  which  are  normally  cross-fertilized,  it  is  not  a 
necessary  antecedent  of  vigour,  and  cannot  have  arisen  as  a  means 
to  that  end.  At  present  we  are  hardly  in  a  position  to  discuss 
this  subject.  Later,  when  we  have  collected  a  large  array  of  facts, 
we  shall  be  able  to  deal  with  it  to  greater  advantage. 

4.  The  multicellular  individual,  then,  consists  of  various  kinds 
of  cells  (each  of  which  corresponds  to  a  unicellular  organism)  which 
perform  different  functions,  each  kind  its  own  special   function. 
Some  of  these  cells  are  germ-cells,  the  rest  are  body  or  '  somatic ' 
cells.     The  latter,  which  are  usually  much  the  more  numerous, 
provide  the  former  with  shelter  and  nutrition,  much   as  worker 
bees  shelter  and  nourish  queens  and  drones.     They  never  unite, 
never  '  conjugate,'  in  the  way  that  sperms  and  ova  do.      Only  the 
germs  are  marriageable ;  and,  as  we  have  just  seen,  in  the  great 
majority  of  animals  and  plants  they  observe  the  degrees  of  con- 
sanguinity very  strictly,  and  do  not  unite  except  with  members  of 
another  cell-community,  and  then  only  to  found  a  new  colony  of 
cells,  an  offspring. 

5.  In  each  sperm  and  ovum  is  a  dot,  the  nucleus.    The  essential 
feature  of  the  union  of  sperm  and  ovum  is  now  believed  to  be  the 
union,  the  intimate  mixture,  of  their  nuclei,  so  that  the  two  nuclei 
become  one.     Under  high  powers  of  the  microscope  there  may  be 
seen  within  the  nucleus  specks  and  threads  of  a  substance  known 
as  chromatin.      When  the  fertilized  ovum  and  its  descendant  cells 
divide  into  daughter-cells,  the  chromatin,  which  grows  with  the 
cells,   displays   remarkable   movements,    and    is    distributed,    ap- 
parently with  great  quantitative  equality,  between  the  daughters, 
thus  forming  their  nuclei.     Now  this  chromatin,  contained  in  the 
germ-cells,  is  believed  with  some  reason  to  be  the  germ-plasm,  the 
'bearer   of  heredity,'  the  substance  that   carries   the  'hereditary 
tendencies,'1  which  direct  development,  and  thus  determine  the 
kind  of  individuals  that  shall  arise  from  the  germ-cells.     A  man 
differs  greatly  from  an  elephant  because  the  germ-plasms  of  the 

1  I  fear  the  expression  '  hereditary  tendency  '  is  somewhat  clumsy.  I  use  it 
for  lack  of  a  better  and  imply  nothing  mystical.  I  mean  no  more  by  it  than  those 
potentialities  for  development  which  are  carried  by  germ-cells.  These  poten- 
tialities differ,  of  course,  with  every  species,  and  indeed  with  every  individual. 
Thus  the  hereditary  tendencies  of  a  man  are  those  which  enable  him  to  develop 
from  a  human  germ  into  a  human  being.  He  does  not  develop  into  a  rabbit 
or  a  tree,  because  the  hereditary  tendencies  of  human  germs  are  such  that  rabbits 
and  trees  cannot  arise  from  them.  From  a  developmental  point  of  view  the  germ- 
plasm  is  compounded  of  structures  carrying  hereditary  tendencies.  By  this, 
however,  I  do  not  mean  that  definite  structures  in  the  germ-plasm  carry  definite 
tendencies,  each  structure  a  tendency.  I  know  nothing  about  that. 


4  THE  CHARACTERS  OF  LIVING  BEINGS 

two  species  are  very  different.  He  differs  yet  more  from  a  plant, 
because  the  germ-plasms  are  yet  more  different.  One  man  re- 
sembles another  because  all  human  germ-plasm  is  much  alike,  but 
every  man  differs  somewhat  from  every  other,  because  the  germ- 
plasm  contained  in  no  two  germ-cells  is  exactly  similar.  A  species 
undergoes  evolution  when,  and  only  when,  its  germ-plasm  under- 
goes change.  When,  by  careful  breeding,  we  improve  our  domestic 
animals  and  plants,  the  alteration  is,  in  essence,  always  a  germinal 
change. 

6.  It  is  now  believed  by  almost  every  one  who  has  an  adequate 
acquaintance  with  the  facts  that  the  organic  world,  the  world  of 
plants  and  animals,  arose  by  processes  of  evolution.     Even  people 
who  still  deny  the  whole  truth  admit,  and  have  always  admitted, 
a  large  part  of  it.     Thus  all  men  believe  that  the  various  branches 
of  the  human  species  had  origin  in  a  common  stem — Adam  and 
Eve,  heathen  deities,  a  species  of  lower  animals,  it  matters  not 
which.      But   human   races   have   since  diverged  widely  in    size, 
shape,  colour,  and  many  other  traits.     Moreover,  the  direction  of 
the  change  has  always  been  such  that  every  race   has    become 
particularly  well-fitted  to  the  surroundings  in  which  it  has  long 
dwelt.    Thus  Englishmen  flourish  better  in  England  than  Negroes,1 
who,  on  the  other  hand,  are  better  adapted  to  conditions  of  life 
prevalent  in  West  Africa.     The  reality  of  evolution,  therefore,  is 
not  in  dispute.     Only  the  extent  of  it  is  disputed,  and  only,  as 
a  rule,  by  people  whose  knowledge  is  correspondingly  limited. 

7.  We   need    not   pin    our   faith   to   the   hypothesis   that   the 
chromatin  is  the  germ-plasm  ;  we  need  not  even  suppose  that  the 
germ-plasm  is  contained  wholly   or  even  mainly  in  the  nucleus. 
Nor  need  we  accept  any  theories  as  to  the  composition  of  it.     But 
some  such  substance  there  must  be  in  the  germ-cell,  some  sub- 
stance  which   is   the   germ-plasm,  the   bearer   of  heredity ;    and 
probability   points   to    it    being   the   chromatin   of   the    nucleus. 
One  very  important  point  to  which  we  shall  have  to  refer  again 
and  yet  again  should  be  noted.     Since  the  offspring  of  the  same 
parents    invariably   differ   more    or    less    among    themselves,    it 
follows  that,  though  the  quantitative  division  of  the  chromatin 
is  apparently  exact,  the  qualitative  division  may  not  be  so.     The 
daughter-cells  may  receive  similar  quantities ;    but  it  is  possible 
that  they  do  not  receive  exactly  similar  kinds  of  germ-plasm. 

8.  The  whole  of  the  child,  therefore,  is  derived  from  a  single 
cell,  the  fertilized  ovum,  which  in  turn  was  derived  wholly  from 

i  See  §  439- 


THE  CONTINUITY  OF  THE  GERM-PLASM  5 

two  germ-cells,  one  from  each  parent,  and  these  again  were  each 
derived  by  single  lines  of  descent  (i.e.  lines  in  which  no  con- 
jugation occurred)  from  the  fertilized  ovum  whence  each  parent 
sprang.  Never  in  all  the  generations  between  fertilized  ovum 
and  fertilized  ovum  does  conjugation  take  place.  The  somatic 
cells  of  the  parent,  therefore,  as  far  as  we  know,  contribute  no  living 
elements  to  the  child  ;  they  merely  provide  temporary  shelter  and 
nutriment.  The  child,  therefore,  does  not,  as  is  popularly  supposed, 
resemble  his  parent  because  his  several  parts  are  derived  from 
similar  parts  of  the  parent — his  head  from  his  parent's  head,  his 
hands  from  his  parent's  hands,  and  so  forth  ;  he  resembles  him  only 
because  the  germ-plasm  which  directed  his  development  was  a 
split-off  portion  of  the  germ-plasm  which  directed  the  develop- 
ment of  the  parent.  The  egg  produces  the  fowl,  but  the  fowl 
as  a  whole  does  not  produce  the  egg — only  one  cell  from  the  fowl, 
the  fertilized  ovum,  produces  it. 

9.  The  germ-cells  are,  in  a  real  sense,  immortal.    Saving  acci- 
dents, they  divide  perpetually,  and  at  intervals  conjugate,  and  there 
is  no  dead  body.     In  like  manner  the  germ-plasm  is  potentially 
immortal.     It  grows  and  divides  into  separate  portions,  but  does 
not  die  unless   killed  or  starved.     Each  fertilized   ovum    builds, 
with   mortal   cell-descendants,   a   temporary  dwelling,  the   body, 
around   its  potentially  immortal  descendants,  the  germs,    which 
hand  on  to  succeeding  generations  their  all-important  trust,  the 
germ-plasm.     Thus  there  is  '  continuity  of  the  germ-plasm!     This 
conception  of  continuity  is  one  of  the  main  pillars  of  the  modern 
science  of  heredity.      It  is  of  very  recent   origin.      Darwin,    for 
example,  believed  that   the  somatic  cells  emitted   minute  living 
representatives,  *  gemmules,'  as  he  termed  them,  one  of  which  from 
each  cell  found  its  way  to  each  germ  and  re-constituted  the  germ- 
plasm.     The  germ-plasm,  therefore,  was  supposed    to  be  formed 
afresh  in  each  germ,  when,  of  course,  there  could  be  no  continuity ; 
and  the  various  parts  of  the  child  would  be  derived  from  corre- 
sponding parts  of  the  parent.     It  is  now  known,  however,  that  the 
information  on  which  Darwin  relied  was  founded  on  a  mistaken 
interpretation  of  the  facts.     Contrary  to  what  he  supposed,  the 
evidence  is  massive  that  parental  '  acquirements '  are  never  '  trans- 
mitted '  to  offspring. 

10.  Under  the  constant  direction  of  its  hereditary  tendencies 
the    fertilized    ovum    proliferates,   and    the   cell-community   thus 
originated  grows  (develops)  through  the  continued  but  regulated 
multiplication   of  cells,   and   so   takes   shape   as   an  'individual,' 


6  THE  CHARACTERS  OF  LIVING  BEINGS 

animal  or  plant.  Nutriment  supplies  the  materials  for  all  this 
increase.  But  more  than  material  is  needed.  Neither  growth  nor 
any  other  form  of '"vital'  activity  ever  occurs  except  as  a  reaction  to 
some  appropriate  kind  of  stimulus.  This  capacity  to  assimilate 
nutriment,  and  to  react  in  certain  other  peculiar  ways  to  certain 
definite  stimuli,  are  the  marks  of  a  living  being.  There  are,  then, 
three  necessary  factors,  in  the  absence  of  any  of  which  growth 
cannot  occur  in  living  beings.  The  first  is  tendency  (capacity, 
potentiality)  to  grow,  which  determines  the  kind  of  development 
that  shall  occur.  The  second  is  stimulus,  which  awakens  the 
tendency.  The  third  is  nutriment,  which  supplies  the  materials 
for  growth,  the  clay  and  the  straw  out  of  which  the  bricks  are 
made.  Hereditary  tendencies  are  internal  factors  traceable  ulti- 
mately to  the  germ-plasm,  but  both  nutriment  and  stimuli  proceed 
from  the  world  external  to  the  growing  structure.  Usually  not 
only  the  kind  of  growth,  but  the  extent  of  it,  is  determined  by  the 
hereditary  tendencies.  Thus,  no  matter  how  abundant  the  supply 
of  nutriment  and  stimulus,  neither  mouse  nor  elephant,  for  example, 
can  increase  beyond  a  certain  size,  which,  within  narrow  limits,  is 
definite  for  the  species.  In  other  words,  stimuli,  which  are  capable 
of  exciting  growth  in  one  period  of  life  (when  the  animal  is  young) 
cease  to  be  capable  of  exciting  it  at  another  (when  the  animal  is 
adult),  no  matter  how  large  the  supply  of  nutriment.  The  limits 
of  growth,  however,  are  much  less  rigidly  drawn  in  plants,  some  of 
which,  indeed,  seem  capable  of  endless  growth,  as  when  propagated 
by  cuttings.  It  should  be  noted  that  nutriment  supplies,  not  only 
the  materials  for  growth,  but  acts — sometimes,  not  always — as 
stimulus  as  well.  Thus  female  bees  develop  in  one  way  (becoming 
queens)  if  one  kind  of  food  is  supplied,  and  in  another  way 
(becoming  workers)  if  they  receive  a  different  kind  of  food.1 

1  May  I  beg  the  reader  to  pay  especial  attention  to  this  paragraph.  There  is, 
I  believe,  nothing  in  it  disputable  ;  but  a  great  deal  that,  in  effect,  is  disputed 
hinges  on  it.  The  points  to  which  I  wish  particularly  to  call  attention  are  these  : 
(i)  An  individual  can  develop  only  within  limits  which  are  predetermined  by 
'  hereditary  tendencies  '  that  have  their  roots  in  his  germ-plasm.  Thus  a  man 
could  not  develop  a  human  limb,  nor  increase  the  size  of  his  muscles  by  use,  nor 
heal  a  wound  of  the  limb  by  a  scar  unless  his  germ-plasm  was  of  a  kind  that 
enabled  him  to  respond  to  the  right  stimuli  in  the  right  way.  (2)  An  individual 
makes  no  growth,  develops  in  no  way,  unless  he  is  stimulated  to  develop  in  that  way 
by  the  right  stimulus,  which  may  be  nutriment,  or  use,  or  injury,  or  something 
else.  (3)  Nutriment  furnishes  the  materials  (the  clay  and  the  straw)  for  all 
growth.  It  also,  as  I  say,  acts,  apparently,  as  the  stimulus  for  some  growth.  In 
other  words  some  growth  occurs,  apparently,  merely  because  the  individual 
absorbs  nutriment :  here  nutriment  acts  both  as  material  for  growth  and  as 
stimulus  to  it.  But  in  other  cases  growth  occurs  only  under  the  stimulus  of  use 


THE  STIMULI  FOR  GROWTH  7 

11.  Living  beings  develop  mainly  under  the  influence  of  three 
distinct  kinds  of  stimuli — nutriment,  use,  and  injury.     To  take  the 
example  of  the  human  being :  up  to  the  time  of  birth  the  infant 
develops  wholly,  or  at  least  principally,  under   the   stimulus  of 
nutriment.     After  birth  some  of  his  structures  continue  to  grow 
under  this  stimulus,  for  example  his  hair,  his  teeth,  his  external 
ears,  and  his  organs  of  reproduction.     But,  as  regards  other  of  his 
structures,  though  nutriment  continues  to  supply  the  materials  for 
growth,  it  ceases  to  supply  the  stimulus.     Thus,  no  matter  how 
well  the  child  is  fed,  the  muscles  of  his  limbs  do  not  develop  unless 
they  are  used.     It  is  a  noticeable  fact  that  structures — and  those 
structures  only — which  grow  under  the  influence  of  use,  tend  to 
atrophy  when  disused.     Thus  disuse,  or  lessened  use,  diminishes 
the  size  of  the  muscles  in  a  human  limb,  while  under  similar  con- 
ditions  the    external   ears   and    the   reproductive   organs   persist 
unchanged.       Since   the   development   which   occurs    under    the 
stimulus  of  use  is  always  a  mere  extension — though  often  a  most 
important  extension — of  that  which  occurs  under  the  stimulus  of 
nutriment,  it  is  frequently  difficult  to  distinguish  structures  which 
owe  their  growth  wholly  to  nutriment  from  those  which  owe  it  in 
part  to  use.     But  the  tendency  of  the  latter  class  to  atrophy  when 
disused  supplies  us  with  a  rough  criterion.1    Lastly,  if  the  individual 
be  injured,  as  by  a  cut,  the  wound  supplies  the  stimulus  for  the 
growth  which  occurs  during  the  process  of  healing. 

12.  Other  stimuli  to  growth  besides  nutriment,  use,  and  injury, 
exist,  though  we  need  not  pause  to  discuss  them  at  length.      Thus 
all  organs  develop  within  a  certain  range  of  temperature,  and  best 

or  injury  ;  here  nutriment  furnishes  only  the  materials.  The  reader  will  see 
later  that,  for  the  sake  of  convenience,  I  include  under  '  nutriment '  a  number 
of  other  stimuli,  but  that  I  sharply  distinguish  from  it  use  and  injury.  He  will 
find  that  the  reason  why  I  include  a  number  of  stimuli  under  the  heading  of 
nutriment,  but  exclude  from  that  category  use  and  injury,  is  because  biologists 
are  accustomed  to  term  all  characters  which  arise  under  the  stimulus  of  use  and 
injury  '  acquirements,'  whereas  all  other  characters  are  termed  by  them  '  inborn  ' 
or  '  innate.'  The  effect  of  distinguishing  characters  by  means  of  the  stimuli 
under  which  they  arise,  rather  than  by  the  words  '  innate  '  or  '  acquired,'  will  be 
to  make  us  take  a  view  of  heredity  and  evolution,  especially  mental  heredity  and 
evolution,  immensely  different,  but  I  think,  demonstrably  more  correct  and 
comprehensive  than  the  view  hitherto  accepted. 

1  The  criterion  is  very  rough,  however.  If  a  structure  atrophies  under  disuse 
then,  as  far  as  I  am  aware,  we  may  be  sure  it  has  grown  under  the  influence  of 
use.  But  it  is  not  true  that  all  structures  which  have  grown  under  the  influence 
of  use  atrophy  when  disused.  Thus  the  bones  of  the  limbs  grow  under  the  influence 
of  use,  but  they  do  not  atrophy  like  the  muscles,  at  least  to  the  same  extent,  when 
disused.  Apparently  this  is  due  to  the  fact  that  bones  are  not  to  the  same  extent 
composed  of  living  cells. 


THE  CHARACTERS  OF  LIVING  BEINGS 

only  within  narrow  limits  which  are  not  the  same  for  every  species. 
Some  organisms  develop  markedly  diverse  characters  at  different 
temperatures.  Light  is  essential  to  the  development  of  very  many 
species,  especially  of  plants.  Certain  plants  develop  in  one  way 
in  the  water,  and  in  another  way  on  the  land.  A  brine  shrimp 
(Artemia)  develops  one  form  in  brackish  water  and  another  in 
water  that  is  salter.  Within  the  animal  body  the  'internal' 
secretion  of  various  glands  exercises  an  important  influence  on  the 
development  of  many  organs.  For  the  purposes  of  our  discussion, 
however,  all  these  stimuli,  and  others  besides,  may  be  bracketed 
with  nutriment,  use,  or  injury  ;  they  are,  in  effect,  in  many  cases 
at  least,  conditions  under  which  nutriment  and  use  act  as  stimuli, 
or  which,  when  in  excess,  produce  injury. 

13.  All  the  characters  which  it  is  possible  for  an  individual 
under  any  circumstances  to  possess  are  traceable  ultimately  to  an 
inter-action  between  the  environment  and  hereditary  tendencies  or 
potentialities  which  have  their  roots  in  the  germ-plasm.      Because 
the  germ-plasm  of  a  dog  differs  from  that  of  a  man,  because  the 
hereditary  tendencies  are  different,  the  two  animals  develop  into 
very  different  individuals,  and  would  so  develop  though  placed 
under  identical  conditions  as  regards  nutriment,  use,  and  injury. 
On  the  other  hand,  if,  were  it  possible,  two  human  germs  were 
exactly  alike  in  all  their  potentialities,  differences  of  nutriment, 
use,  and  injury  would  cause  corresponding  differences  between  the 
individuals  that  arise  from  them.     The  human  arm  first  develops 
under  the  stimulus  of  the  nutriment  that  reaches  it  from  the  world 
external  to  it,  because  of  an  antecedent  potentiality  in  the  germ- 
plasm.     For  the  same  reason  it  continues  to  grow  under  the  in- 
fluence of  use,  or,  when  it  is  damaged,  under  the  stimulus  of  injury. 
Stimulus  is  the  invariable  antecedent  to  all  growth. 

14.  Since  no  character  can  be  used  or  injured  until  it  exists, 
the  power  of  growing  under  the  stimulus  of  nutriment  must  have 
been  the  very  first  product  of  evolution,  the  first  peculiarity  by 
which  living  beings  were  distinguished  from  mere  chemical  com- 
pounds.    Possibly  the   earliest  living   beings   were  homogeneous 
throughout,  consisting  altogether  of  a  primitive  kind  of  germ-plasm, 
there  being  no  cell-body  as  distinguished  from  the  nucleus,  no 
'  cyto-plasm '  properly  so  called,  in  which  case  the  minutest  living 
fragment  was  perhaps  capable  of  continuing  the  species.     Probably 
also  each  organism  was  capable  of  indefinite  growth,  or  at  least 
of  an  amount  of  growth  which  was  limited  only  by  the  supply  of 
nutriment.     The  individual,  however,  can  never  have  been  large ; 


GROWTH  IN  RESPONSE  TO  INJURY  9 

for,  with  very  primitive  organization,  the  passage  of  food  from  the 
periphery  to  the  centre  through  living  and  assimilating  tissue 
cannot  have  been  great.  Very  possibly,  too,  these  lowly  organisms 
were  so  loosely  compacted  that  they  easily  fell  to  pieces  under 
shocks  from  the  environment.  Every  fragment,  then,  constituted 
a  member  of  the  species.  Doubtless  definite  shape  and  size,  as 
well  as  definite  differentiation  of  structure  within  the  individual 
and  particular  methods  of  reproduction  which  resulted  therefrom, 
such  as  periodic  self-division,  were  products  of  prolonged  evolution. 
Probably  the  lowest  living  beings  which  we  are  capable  of  distin- 
guishing as  living,  even  under  the  highest  powers  of  the  microscope, 
are  products,  as  regards  size  and  in  other  ways,  of  ages  of  evolution. 
So  far,  of  course,  all  is  pure  conjecture ;  but  it  is  something  more  than 
conjecture  that  early  evolution  must  have  consisted  of  such  changes 
in  the  germ-plasm,  such  changes  in  the  hereditary  tendencies,  that 
each  species  came  to  respond,  by  growing  in  its  own  particular 
way,  to  the  stimulus  of  nutriment,  and  so  evolved  its  own  peculiar 
characteristics. 

15.  We  can  guess  only  vaguely  at  the  stage  of  evolution  at 
which   the   power  of  responding   by  growth  to  the  influence  of 
injury,  and  so  repairing  damaged  structures,  first  appeared.     If  the 
primitive  living  beings  were  capable  of  indefinite  growth,  but  not 
of    spontaneous   self-division,    then   this   continued   growth   after 
fragmentation    in    itself  constituted  a   sort   of    repair   of  injury. 
Probably,  therefore,  the  power  of  responding  to  the  stimulus  of 
injury  was  evolved  concurrently  with  that  of  responding  to  the 
stimulus  of  nutriment  and  was  originally  part  of  and  indistinguish- 
able from  it.     Even  in  higher  types,  unicellular  and  multicellular, 
which  have  evolved   heterogeneous   structures   and   are  of  more 
or   less   definite   shapes   and   sizes,   the   underlying    resemblance 
remains ;    nutriment   stimulates    the    individual    to  produce   the 
characters  of  the  species,  injury  stimulates  him  to  reproduce  them 
more  or  less  perfectly  when  they  are  lost  or  damaged. 

1 6.  This  power  of  reproducing  lost  or  damaged  parts,  of  growing 
under  the  stimulus  of  injury,  varies  greatly  in  different  species  and 
in  different  structures  of  the  same  species.     Since  it  is  a  product 
of  evolution,  since  it  is  one  of  the  means  by  which  organisms  are 
adapted  to  the   environment,  its   degree  of  development  in  any 
species   or   structure   is   proportionate   to    its    utility.     Relatively 
speaking,  the  higher  animals,  which  have  very  complex  organiza- 
tions and  lead  very  active  lives,  possess  it  in  small  measure.     As 
a  rule  they  replace  important  losses  of  tissue  only  by  scars.     It  is 


io  THE  CHARACTERS  OF  LIVING  BEINGS 

advantageous  to  a  deer,  for  example,  to  be  able  to  heal  a  wound, 
but  the  conditions  of  its  life  are  such  that  it  would  very  rarely  have 
time  or  opportunity  to  reproduce  a  lost  limb.  In  effect  the  power 
to  do  so  would  be  useless.  The  stag,  however,  habitually  re- 
produces its  lost  antlers.  They  are  very  heavy  structures  which 
are  useful  to  him  at  the  season  when  he  contends  with  his  rivals ; 
but  burdensome,  and  therefore,  not  only  useless  but  worse  than 
useless,  at  other  times.  He  sheds  them,  it  is  true,  in  the  absence 
of  injury,  but  the  whole  process  closely  resembles  loss  and  repro- 
duction through  injury,  and  demonstrates  the  difficulty  of  drawing 
a  sharply  dividing  line  between  nutriment  and  injury  as  stimuli. 

17.  Some    plants    which    sprang    originally   from    germ-cells 
multiply  indefinitely  by  budding.     Each  bud  is  regarded  by  botan- 
ists as  a  '  person,'  but  a  person  in  this  sense  is  not  quite  the  same 
as  an  '  individual '  which  takes  origin  in  a  germ.     Buds,  even  when 
growing  separated  from  the  parent,  are,  in  a  real  sense,  portions  of 
the  individual  that  rose  from  the  germ.     If  we  amputate  the  end 
of  a  twig  the  injury  may  or  may  not  heal  as  a  scar,  but  the  pro- 
duction of  buds  is  commonly  increased.     Are  they  to  be  regarded 
as   developing   under   the  stimulus  of  nutriment,   or   of  injury? 
Here  again  we  see  the  close  connexion  between   the   power  of 
responding  to  the  stimulus  of  nutriment  and  that  of  responding  to 
the  stimulus  of  injury.     Injury,  indeed,  may  be  regarded  as  one  of 
the  conditions  under  which  the  stimulus  of  nutrition  comes  into 
action.     It  awakens  a  power  which  has  slumbered. 

1 8.  Some  animals  lose  living  and  active  parts  by  injury  almost 
as  regularly  and  replace  them  almost  as  readily  as  the  stag  his 
antlers  or  the  bear  his  winter  coat.     Thus  in  some  newts  the 
external  gills  are  much  exposed   and  liable  to  be  bitten  off  by 
members  of  the  same  species.     They  are  readily  replaced,  whereas 
internal  parts  of  the  same  animal  show  small  powers  of  regenera- 
tion': they  merely  heal.1     Lizards  which  frequently  escape  from 
enemies  with  the  loss  of  the  tail  are  able  to  reproduce  it;  but 
they  cannot  reproduce  a  limb,  the  loss  of  which  usually  involves 
capture  and  death.    The  power  of  regeneration2  possessed  by  fishes 
is  apparently  no  greater  than,  if  as  great,  as  that  possessed  by 
mammals.     Some  worms,  much  exposed  to  injury,  are  able  to 

1  Weismann,  Theory  of  Evolution,  vol.  ii.  pp.  12-13. 

2  The  term  regeneration  is  usually  limited  to  a  more  or  less  perfect  replace- 
ment of  the  lost  part  or  tissues  by  similar  structures  ;    whereas  in  mere  healing 
a  scar,  which  may  differ  greatly  from  the  lost  part,  is  developed.     The  two 
processes  differ  in  degree,  not  in  kind,  and  are  united  by  gradations.    Regeneration 
is  very  perfect  healing  ;   healing  is  imperfect  regeneration. 


GROWTH  IN  RESPONSE  TO  USE  11 

reproduce  the  whole  individual  from  a  fragment.  Great  powers  of 
regeneration  are  the  rule  in  plants  or  parts  of  plants  which  are 
exposed  to  injury  from  animals,  for  example  in  grasses. 

19.  The  power  of  responding  to  the  stimulus  of  injury,  then,  is 
clearly  allied  to  and  is  derived  from  the  power  of  responding  to 
the   stimulus   of  nutriment.     The   germ-plasm  of  every  type  of 
animal  and  plant  has  so  changed  from  the  primitive  kind  that 
under  the  stimulus  of  nutriment  the  individual  tends  to  develop 
the  characteristics  which  evolution  conferred  on  his  immediate 
predecessors ;  it  has  also  so  changed  that  wherever  the  power  of 
regeneration  is  useful,  and  to  the  extent  to  which  it  is  useful,  injury 
stimulates  to  the  replacement  or  repair  of  lost  or  damaged  parts. 
Like  the  power  of  growing  under  the  stimulus  of  nutriment,  the 
power  of  repairing  injury  is  always  an  adaptation.     The  kind  of 
repair  that  normally  occurs  is  ever  the  most  useful  and  extensive 
possible  under  the  conditions. 

20.  The  characters  which  develop  under  the  stimulus  of  injury 
are  interesting  and  important,  but  vastly  more  interesting,  both 
from  the  theoretical  and  the  practical  standpoint,  are  those  which 
develop  under  the  stimulus  of  use.     If  we  study  almost  any  work 
on  the  sister  subjects,  heredity  and  evolution,  published  more  than 
a  decade  ago,  and  a  great  many  published  since,  we  frequently 
meet  an  entirely  unwarrantable  assumption — the  assumption  that 
all  structures  and  organs  in  all  types  of  living  beings  tend  to  grow 
and  develop  if  used.     For  example,  the  celebrated  Lamarck,  the 
predecessor  and  in  a  way  almost  the  peer  of  Darwin,  who  during 
the  nineteenth  century  exerted  an  immense  influence  on  biological 
thought,  founded  his  theory  of  racial  change  on  the  supposition 
that  all  structures  and  qualities  are  capable  of  increase  under  the 
influence  of  use  and  decrease  under  that  of  disuse.     The  same 
idea  bulks  largely  in  the  writings  of  Spencer,  Lewes,  Romanes, 
Cope,  and  a  multitude  of  others. 

21.  In  man,  as  we  have  seen,  certain  structures  grow  under  the 
influence  of  use,  but  the  amount  even  of  this  growth  (i.e.  multi- 
plication of  cells)  is  by  no  means  strictly  proportionate  to  the 
amount   of  use,   and    is   always   rigidly    limited.     Different  men 
respond   in   different  degrees  to  the  stimulus  of  use,  but  even  a 
1  natural '  athlete  can  increase  the  size  of  his  muscles  only  up  to  a 
certain  point,  after  which  cell-multiplication  no  longer  occurs,  no 
matter  how  much  he  uses  his  muscles.     All  growth  due  to  use 
occurs  mainly  during  early  life ;  in  old  age  it  practically  ceases  in 
most  structures  though  they  are  still  used.     Lastly,  the  growth  of 


12  THE  CHARACTERS  OF  LIVING  BEINGS 

some  structures,  for  example,  the  hair,  teeth,  nose,  external  ears 
and  reproductive  organs,  is  apparently  not  influenced  in  the 
slightest  degree  by  use.  It  is  plain,  therefore,  that  the  power  of 
growing  under  the  influence  of  use,  unlike  that  of  responding  to 
injury,  is  not  a  property  common  to  all  or  nearly  all  living 
structures.  It  is  present  only  in  some  structures,  and  in  them 
not  equally  at  all  periods  of  life. 

22.  If  we  continue  to  study  the  matter  closely  we  make  another 
discovery  and  a  very  important  one  ;  we  find  that  this  power,  like 
that  of  repairing  injury,  is  present  only  in  structures  where  it  is 
useful,  to  the  extent  to  which  it  is  useful,  and  during  the  time  it  is 
useful.     In  man,  for  example,  it  long  persists  in  the  muscles  of  the 
limbs  and  in  the  heart  and  kidneys,  which  even  in  advanced  age 
hypertrophy  under  increased  strain.     But  no  structures  are  more 
used  than  the  joints.     With  the  rest  of  the  limbs  they  grow  under 
the  influence  of  use  during  youth,  after  which  the  power  of  so  grow- 
ing, which  would  then  be  useless,  indeed  injurious,  departs  from 
them.     The  tongue  again  is  a  structure  which  is  immensely  used. 
We  do  not  know  whether  it  grows  in  part  under  the  stimulus  of 
use  or  only  under  that  of  nutriment ;  but,  in  any  case,  growth 
ceases  when  adult  life  is  attained  ;  for  no  amount  of  use,  apparently, 
can    add    anything   to   it    subsequently.      Manifestly,    therefore, 
the   power    of  growing    under   the    stimulus    of  use    is   also   an 
adaptation.     It  is  not  a  necessary  property  of  all  living  protoplasm, 
but  a  thing   which  has   been    implanted   in  some  structures   by 
evolution. 

23.  Moreover  we  have  massive  evidence  that  it  is  a  late  and  a 
high  product  of  evolution.     It  does  not  date  back  to  the  origin  of 
life  like  the  faculties  of  growing  in  response  to  the  stimuli  of 
nutriment  and  injury.    It  is  observable  only  in  the  higher  organisms, 
and  in  its  greatest  development  only  in  the  highest.    Thus  a  human 
infant  is  born  very  immature  and  helpless ;  it  owes  most  of  its 
subsequent  growth,  its  advance  towards  maturity,  mainly  to  use. 
A  young  foal  is  born  better  developed  ;  it  owes  less  to  use  and  more 
to  the  stimulus  of  nutriment.     There  is  evidence  that  amphibians 
(e.g.  frog)  and  fish  owe  little  or  nothing  to  use ;    they  seem  to 
develop  perfectly,  or  at  least  very  well,  when  so  rigidly  confined 
that  use  has  no  great  scope  to  act  as  a  stimulus.     Most  insects 
seem  to  grow  wholly  under  the  stimulus  of  nutriment  (and  injury). 
Certainly  use  plays  no  part  in  bringing  about  the  changes  which 
occur  during  their  metamorphoses.     Lower  in  the  animal  scale 
there  is  even  less  probability  that  use  plays  any  part  in  develop- 


NORMAL  GROWTH  AN  ADAPTATION  13 

ment  Some  plants  grow  tougher  and  more  firmly  rooted  when 
exposed  to  strong  winds  ;  but  throughout  the  vegetable  kingdom 
the  faculty,  if  present  at  all,  is  developed  only  in  the  slightest 
degree.  At  present,  however,  we  need  not  labour  this  question  of 
the  evolution  of  the  power  of  growing  in  response  to  use.  We 
shall  be  in  possession  of  much  more  definite  and  decisive  evidence, 
especially  when  we  consider  mind. 

24.  In  brief  the  notion  that  the  power  of  growing,  especially  of 
growing  adaptively,  under  the  stimulus  of  use,  is  present  in   all 
living  tissues,  is  merely  a  vague  guess  founded  on  popular  observa- 
tion of  our  familiar  human  development.     There  is  no  veil  like  the 
veil  of  familiarity.    Never  yet  has  this  question  been  made  the  subject 
of  close  and  accurate  investigation.     Since  some  human  structures 
develop  in  this  way,  it  has  been  assumed  that  all  structures  in  all 
animals  and  plants  can,  and  do,  so  develop.     Like  many  other 
popular  guesses  it  has  been  accepted  quite  without  question  even  by 
thinkers  in  science.     Vast  systems  of  philosophy  have  been  built 
on  it  and  acclaimed  as  the  highest  products  of  human  wisdom. 
But  it  is  very  doubtful  whether  any  other  error  in  the  whole  range 
of  biology,  indeed   of  scientific  thought,  has  been  productive  of 
more   confusion,    futile  discussion    and    practical    mischief.      My 
language  is  strong,  but  the  reader  will  find  it  fully  justified.1 

25.  Obviously,   then,   powers    of   developing    in   response    to 
definite  stimuli  are,  in  the  case  of  all  species,  delicate  adjustments 
to  the  environment.     If  any  individual  varies  from  the  ancestry  so 
as  to  lose  this  adjustment,  this  power  of  responding  by  growth  in 
definite  ways  to  definite  stimuli,  he  fails  to  develop  the  right  char- 
acters to  the  right  extent  and  perishes.     Every  type  of  plant  and 
animal,  the  lichen,  the  beetle,  and   the  man,  for  example,  fits  its 
own  niche  in  nature  as  the  hand  does  the  glove ;  but  it  fits  only 
because  its  germ-plasm  has  been  so  fashioned  by  evolution  that 
every  normal  individual  grows  into  adaptation  to  his  environment 
in  response  to  stimuli. 

26.  Speaking    generally,    all    growth    is    either    immediately 
adaptive  or  is  a  provision  for  future  adaptation.     Thus  human 
germ-cells  are  adapted  by  their  structures  and  capacities  for  exist- 
ence in  the  testes  and  ovaries.     Under  the  stimulus  of  nutriment 
they  develop   into   embryos   and  thus  are  able   to  fit  the   next 
environment,  the  uterus.     Here  they  continue  to  develop  till  they 
grow  into  fitness  for  life  in  the  mother's  arms.     Thereafter,  use  and 
injury  come  into  play ;  and,  with  some  characters  developing  under 

1  See*chapter  iv. 


14  THE  CHARACTERS  OF  LIVING  BEINGS 

one  stimulus,  some  under  another,  and  some  under  a  third,  and  all 
developing  in  proportion,  the  infant  gradually  becomes  adapted  to 
the  environments  of  the  child  and  the  adult.  If  he  be  injured, 
development  begins  by  stoppage  of  the  blood-flow  and  continues  till 
growth  is  complete  and  a  scar  forms.  Since  every  one  is  injured  atone 
time  or  another,  without  this  healing  life  would  be  impossible  under 
conditions  normal  for  the  species.  As  we  have  just  seen,  growth 
under  the  stimulus  of  use  is  also  a  part  of  normal  development- 
The  human  being  cannot  become  a  normal  adult,  fit  for  the  struggle 
of  existence,  without  it. 

27.  It  is  clear  then  that  all  characters  that  it  is  possible  for  the 
individual  to  develop  are  equally  rooted,  as  it  were,  in  the  germ- 
plasm.      Manifestly  no  character  is  more  closely  or  less  closely 
connected  with  it  than  any  other.     But  the  traits  which  develop 
under  the  stimulus  of  nutriment  have  two  characteristics  which 
have  so  impressed  students  of  heredity  that  attention  has  been 
especially  concentrated  on  them. 

28.  First,   since   no   individual   can    develop   without   food  as 
material  for  growth,  the  stimulus  of  nutriment  is  always  present ; 
and,  therefore,  if  the  individual  lives  long  enough,  all  the  characters 
that  arise  under  its  influence  inevitably  appear  unless  prevented 
by  injury.1     On   the   other  hand,  characters,  which    arose  in  the 
parent  under  the  stimulus  of  injury  or  use,  may  not  arise  in  the 
child,  for  similar  stimuli  may  not  be  received.      Thus  the  only 
effect  of  injury  which  inevitably  appears  in  the  human  being  is  the 
navel.     Other   scars  are   not   reproduced    unless,    as   is   unlikely, 
exactly  similar  injuries   are   received  by   parent   and  child.     In 
every   normal   child    and    adult   certain    effects   of  use   (e.g.   the 
muscular    development   of  the   limbs)   are    always   present,   but 
though  in  practice  we  recognize  them  as  effects  of  use  (for  the 
physical  and  mental  exercises  we  give  our  children  are  nothing 
other  than  conscious  attempts  to  develop  them  in  this  way),  yet  in 
theory  they  are  seldom  recognized  as  such.     Like  other  people, 
students  of  heredity  tend  to  think  in  compartments,  and  in  their 
discussions  they  have  usually  argued  as  if  reactions  to  use  were 
limited  to  such  exceptional  and  trivial  developments  as  the  extra 

1  This  statement  is  not  quite  correct.  Thus,  though  male  characters  are 
latent  in  the  female  and  vice  versa,  and  though  they  arise  under  the  stimulus  of 
nutriment,  they  do  not  develop.  The  individual  has  two  sets  of  sexual  characters, 
the  development  of  one  of  which  is  a  bar  to  the  development  of  the  other.  But, 
apart  from  such  cases  of  alternative  reproduction  in  which  the  development  of 
one  character  prevents  the  development  of  another,  the  statement  that  characters, 
which  arise  in  response  to  the  stimulus  of  nutriment  inevitably  appear  is  true. 


ALL  CHARACTERS  ARE  EQUALLY  ACQUIRED       15 

growth  of  the  blacksmith's  arm  which  results  from  the  nature  of 
his  employment,  or  the  thickening  of  the  skin  in  the  palm  of  the 
hand  which  results  from  rough  labour. 

29.  Second,  since  nothing  can  be  used  or   injured   before   it 
exists,  characters  that  develop  under  the  stimulus  of  nutriment  are 
always  the  first  to  reappear.     They  are  the  earliest  products  both 
of  racial   evolution   and    individual   development.     Therefore   all 
characters  that  arise  through  use  or  injury  are  *  modifications '  of 
those  that  arose  under  the  stimulus  of  nutriment.     But  this  creates 
no  real  distinction,  for  all  growth,  whether  in  the  embryo,  foetus, 
infant,  child,  or  adult,  whether  arising  in  response  to  nutriment, 
injury,  or   use,  is   a   modification,    due   to   cell-multiplication,    of 
previous  growth.     Nevertheless,  since  changes  due  to  the  stimulus 
of  nutriment  arise  gradually  and  insensibly,  whereas  those  due  to 
injury  are  usually  impressed  in  a  very  obvious  way  on  pre-existing 
characters,  and  those  recognized  as  due  to  use  are  also  so  impressed, 
the  first  have  seldom  been  recognized  as  '  modifications,'  while  the 
second  and  third  have  been  so  recognized.    At  any  rate,  the  names 
'  modification J  and  '  acquirement '  have  been  especially  applied  to 
the  effects  of  injury  and  use.    That  is,  it  has  been  implied  that  these 
stimuli  alter  the  individual  in  such  a  way  as  to  make  him  different 
from  what,  if  I  may  use  the  expression,  nature  intended  him  to  be. 
Obviously,  however,  the  reasoning  here  is  superficial  and  inexact. 
The  error  arises  because  the  thinking  is  in  terms,  not  of  the  germ- 
plasm  which  carries  the  hereditary  potentialities  of  individual,  but 
of  the  individual  himself,  who  only  develops  such  of  his  traits  as  he 
happens  to  be  stimulated  to  develop.     As  I  say  all  characters  are 
equally  rooted    in  the   germ-plasm,  all   are  equally  products  of 
evolution,  and  all  arise  equally  in  response  to  stimuli.     They  are 
all  ready  to  arise,  and  they  all  arise  inevitably  if  the  right  stimuli 
be  forthcoming.     Whether  they  do,  or  do  not  arise,  depends,  not 
on  the  nature  of  the  individual,  but  on  that  of  the  environment. 
It   is   as   '  natural '   for    him    to    develop    a   scar   or   a   callosity 
under  the  right  conditions  as  to  develop  a  beard  or  a  hand.     In 
any  case  he  fulfils  his  nature. 

30.  Half    a   century    of  controversy    has    resulted    from    an 
insufficient   appreciation    of  the   fact   that   the   characters   which 
develop  under  the  stimulus  of  injury  and  use  are  as  closely  related 
to  the  germ-plasm,  are  as  natural  to  the  individual,  as  those  which 
develop  under  the  stimulus  of  nutriment.    Biologists  are  accustomed 
to  divide  all  the  characters  of  living  beings  into  those  which  are 
'  inborn '  and  those  which  are  *  acquired,'  and  while  all  biologists 


1 6  THE  CHARACTERS  OF  LIVING  BEINGS 

maintain  that*  inborn'  characters  are 'germinal'  and  tend  to  be 
transmitted  to  offspring,  most  of  them  insist  that  '  acquirements ' 
are  not  germinal  and  are  never  inherited.  If  we  consider  these 
words  carefully  it  becomes  clear  that  by  an  innate  or  inborn 
character  they  imply  one  which  has  developed  under  the  stimulus  of 
nutriment,  whereas  by  an  acquirement  they  imply  one  which  has 
developed  under  the  stimulus  of  use  or  injury ;  when  they  speak  of  an 
innate  character  as  inherited  they  imply  that  in  the  parent  and  child 
alike  it  developed  under  the  stimulus  of  nutriment  ;  and  when,  as  is 
still  sometimes  the  case,  they  allege  the  inheritance  of  a  parental 
acquirement,  they  imply  that  a  character  which  was  developed 
under  the  influence  of  use  or  injury  in  the  parent,  is,  in  the  child, 
TRANSFERRED  to  a  different  category  and  developed  under  the 
stimulus  of  nutriment. 

31.  But  now,  bearing  in  mind  the  foregoing  paragraphs — bearing 
in  mind  that  all  evolution  consists  in  a  germinal  change,  that  a 
germinal  change  consists  in  an  altered  potentiality  to  produce 
characters,  that  obviously  no  characters  can  arise  unless  the  poten- 
tiality to  develop  them  is  present  in  the  germ-plasm  and  unless  it 
is  awakened  by  fitting  stimuli,  that  all  characters  which  are  poten- 
tially present  arise  with  equal  certainty  if  fitting  stimuli  be  applied, 
that  all  growth  is  a  modification  of  pre-existing  characters,  that  no 
characters  are  derived  from  similar  characters  in  the  parent  (e.g. 
the  child's  hand  from  the  parent's  hand)  but  all  take  origin  in  the 
fertilized  ovum,  bearing  in  mind  also  that  the  evolution  of  the  higher 
animals  has  consisted  mainly  in  the  evolution  of  a  power  of  develop- 
ing 'acquirements'  under  the  stimulus  of  use,  and  that  the  mass 
of  characters  developed  under  this  stimulus  is  quite  as  essential  a 
part  of  that  '  normal '  development  whereby  the  maturity  of  the 
individual  is  attained  and  his  survival  secured  as  the  characters 
developed  under  the  stimulus  of  nutriment — bearing  in  mind  all 
this,  let  the  reader  ask  himself  in  what  respects  characters  that 
develop  in  response  to  the  stimulus  of  nutriment  are  more 
germinal,  inborn,  and  hereditary  than  those  which  arise  in  response 
to  other  stimuli.  I  believe  he  will  be  forced  to  conclude  that 
these  expressions  are  erroneous  in  that  they  altogether  fail  to 
indicate,  in  that  they  obscure  rather  than  reveal,  the  true  distinc- 
tions between  classes  of  characters.  They  have  come  into  use 
only  because  biologists,  though  speaking  constantly  of  germinal 
characters,  have  as  constantly  thought  in  terms,  not  of  the  germ- 
plasm,  but  of  the  individual.  Manifestly  no  characters  are  really 
more  germinal,  inborn,  or  inheritable  than  any  others.  All  are 


ONLY  THE  GERM-PLASM  IS  INBORN  17 

germinal,  inborn  and  inheritable  in  exactly  the  same  sense.1  The 
true  distinction  between  the  different  classes  of  characters  are 
indicated  when  they  are  described  as  arising  in  response  to  the 
different  classes  of  stimuli.  If  the  reader  still  thinks  otherwise — 
as  he  will  constantly  be  tempted  to  do  if  he  keeps  his  attention 
fixed,  not  on  the  germ-plasm,  but  on  the  individual — let  him  en- 
deavour to  formulate  a  clear  idea  as  to  what  makes  one  character 
more  inborn  than  another.  He  will  certainly  fail.  Moreover,  if 
he  tries  to  think  of  a  character  of  the  multicellular  individual  which 
is  more  innate  and  inheritable  than  any  other,  he  will  succeed  only 
in  recalling  characters  which  appear  more  regularly  than  others 
merely  because  the  stimulus  which  evokes  the  former  is  received 
more  certainly  than  that  which  evokes  the  latter. 

32.  Occasionally  what  are  known  as  identical  twins  are  born. 
They  are  supposed  to  be  derived  from  a  single  fertilized  ovum. 
They  are  extremely  alike,  presumably  because  their  germ-plasms 
were  similar.     It  is  conceivable  that   the   germ-plasms  might  be 
exactly  similar ;   in  which  case,  under  precisely  similar   stimuli, 
they  would  develop  into  individuals  precisely  similar.     But  if  from 
some  cause,  for  example  a  twisting  of  the  umbilical  cord,  one  twin 
received  an  inferior  supply  of  nutriment,  they  would  differ.    Every- 
one would  then  agree  that  the  difference,  though  one  of '  innate ' 
characters,  would  be  acquired  ;  but  it  would  puzzle  anyone  to  indi- 
cate the  twin  that  made  the  differentiating  acquirement. 

33.  Only   the  germ-plasm,  its  structures,  and  hereditary  tend- 
encies, are  really   inborn   and    inheritable;    for  they  really   pass 
from    ancestral   to   descendant   germ-cells.     The   germ-cell   is   a 
unicellular   organism  which,  like  other  unicellular  types,  divides 
itself  between  its  offspring,  which  in  turn  divide  themselves  in  like 
manner.      The   daughter-cells  and   their   descendants,   therefore, 
inherit  the  structures  and  qualities  of  the  parent  cell  in  a  sense 
quite  different  from  and  much  more  real  than  that  in  which  a  cell- 
community  '  inherits '  the  structures  and  qualities  of  the  community 
from  whence  it  is  derived.2 

1  The  only  conceivable  exception  is  a  temporary  change,  for  example,  an 
injury  (e.g.  a  cut)  considered  apart  from  the  reaction  by  which  it  is  repaired — 
a  reaction  which,  however,  begins  at  once,  or  almost  at  once,  by  coagulation  of 
blood,  etc.  Even  this  exception  is  more  apparent  than  real,  for  an  injury  derives 
its  characteristics  not  only  from  the  agent  which  inflicts  it,  but  also  from  the 
structure  which  receives  it,  which  in  turn  derived  its  characters  from  the  egg. 

z  It  maybe  asked  "  If  the  germ-cell,  the  fertilized  ovum,  divides  itself  between 
its  daughter-cells,  which,  as  well  as  their  descendant  cells,  repeat  the  process,  how 
does  it  happen  that  all  the  cell-descendants  are  not  close  copies  of  one  another 
and  of  the  fertilized  ovum  whence  the  community  sprang  ?  Why  do  some  of  these 

2 


1 8  THE  CHARACTERS  OF  LIVING  BEINGS 

34.  The  names  we  use  do  not  greatly  matter  if  they  serve  to 
indicate  the  truth  ;  an  erroneous  term,  provided  it  is  obviously 
erroneous,  may  convey  a  right  impression.  But  the  words  inborn, 
acquired,  and  inheritable,  appear — when  we  think  of  individuals, 
instead  of  the  germ-plasm  as,  very  naturally,  we  tend  to  do — so 
obviously  correct  that  their  use  has  been,  and  is  still  productive 
of  endless  confusion  and  controversy.1  For  example,  it  was 
formerly  believed  that  parental  acquirements  were  transmissible 
to  offspring:  in  other  words  it  was  maintained  in  effect  that  a 
character  (e.g.  a  scar)  which  the  parent  was  able  to  acquire  in  a 
certain  way  (as  a  reaction  to  injury),  because  a  long  course  of 
evolution  had  rendered  such  acquisition  possible  to  the  members 
of  his  race,  tended  to  be  reproduced  by  the  child  in  a  different 
category  of  characters  and  in  a  way  (as  a  reaction  to  nutriment)  in 
which  no  member  of  his  race  had  ever  acquired  it  before,  and  with 
which,  therefore,  evolution  had  nothing  to  do.  An  actual  miracle 
was  supposed  to  happen,  the  miraculous  nature  of  which  was  con- 
cealed under  a  misuse  of  terms. 

descendants  become  skin-cells,  others  muscle-cells,  and  so  on  ?  What  brings 
about  this  differentiation  amongst  the  cells  of  the  community  ?  "  Two  answers 
to  this  question  are  conceivable.  Though  the  division  of  the  cells  is  apparently 
equal  quantitatively,  it  does  not  follow  that  it  is  equal  qualitatively.  Equal 
amounts  of  germ-plasm  may  pass  into  daughter-cells  ;  but  the  kind  of  germ- 
plasm  which  passes  into  one  daughter  may  not  be  quite  similar  to  that  which 
passes  into  the  other  daughter.  Obviously  if  this  differentiation  were  accentuated 
in  succeeding  cell-divisions  it  would  account  for  the  fact  that  skin  or  bone-cells, 
for  example,  are  so  dissimilar,  not  only  in  appearance  but  more  especially  in 
functions,  from  germ-cells.  That  there  may  be  a  good  deal  of  truth  in  this  hypo- 
thesis is  rendered  probable  by  the  fact  that  not  only  do  the  body  (somatic)  cells 
differ  qualitatively  from  the  germ-cells,  but  the  germ-cells  differ  in  the  same  way 
amongst  themselves  ;  for  they  give  rise  to  cell -communities  (children)  which 
may  present  marked  differences.  The  second  conceivable  explanation  is  that 
the  appearances  and  qualities  which  cells  develop  depend  on  their  environments. 
According  to  this  hypothesis,  a  skin-cell  assumes  the  appearance  and  qualities 
of  its  kind,  not  because  its  germ-plasm  ('  idio-plasm  ')  differs  from  that  of  a  germ- 
or  muscle-cell,  but  because  it  is  differently  situated,  and  therefore  differently 
stimulated.  That  there  may  be  much  truth  in  this  suggestion  also  is  proved 
by  the  fact  that  fragments  of  many  cell-communities,  for  instance  fragments  "of 
begonia  leaf,  which  apparently  contain  no  germ-cells,  are  capable  of  giving  rjse 
to  an  entire  '  person,'  an  entire  cell-community,  which  contains  every  kind  of 
cell;  including  germ-cells.  Possibly  the  true  explanation  lies  in  a  combination 
of  these  hypotheses.  In  other  words,  it  is  possible  that  cells,  like  individuals, 
differ  amongst  themselves  partly  because  they  differ  in  germ-plasm,  and  partly 
because  they  differ  in  environments. 

1  In  the  misuse  of  them  I  have  sinned  as  deeply  as  anyone — see,  for  example, 
The  Present  Evolution  of  Man,  A  Icoholism,  and  The  Principles  of  Heredity.  In 
the  latter  work,  however,  I  made  some  endeavour  to  make  the  situation  clear. 
See  note,  p.  249,  and  especially  the  second  edition,  Appendix  A. 


THE  TRANSMUTATION  OF  CHARACTERS     19 

35.  Most  biologists  now  reject  this,  the  Lamarckian  hypothesis, 
on  the  ground  that  it  is  against  the  weight  of  evidence.     It  is  not 
realized,  however,  that  here  we  have  a  question  not  of  the  trans- 
mission  but  of  the  transmutation  of  characters  ;  for  the  child  is  not 
supposed  to  reproduce  that  which  the  parent  developed  (an  effect 
of  use  or  injury),  but  something  vastly  different  (a  response  to  the 
stimulus   of  nutriment).      As    a   fact    the   evidence   against   the 
Lamarckian    hypothesis    is    very   conclusive.      Characters   which 
evolution  has  fitted  parents  to  develop  under  the  stimulus  of  use 
and  injury  do  not  tend   to  be  automatically  transmuted   in   the 
offspring  into  characters  which   develop    under   the   stimulus   of 
nutriment.     Such  a  change  would  be  as  intrinsically  improbable 
as  a  change  of  eyes  into  ears.     But  the  language  used  has  raised 
a  false  issue,  has  diverted  attention  from  the  real  significance  of 
responses  to  use  and  injury,  and  of  the  evolution  which  enables  the 
individual  to  develop  them.     The  belief,  reached  after  long  and 
heated   controversy,  that  *  acquirements '   are  not  '  inherited,'  has 
caused  nearly  all  students  of  heredity  to  think  of  them  as  mere 
accidents  which  have   no  importance  except  in  so  far   as   they 
obscure  the  outlook  and  render  the  discovery  of  the  truth  difficult. 
Hence,  for   example,   the    notion   that   the   acquirements   of  the 
blacksmith — which  comprise  among  other  things  almost  his  entire 
muscular   development   since  infancy — are  limited  to   the  extra 
development  which   results  from   the  nature  of  his  labour.     We 
shall  see  how  mistaken  is  this  view,  and  how  great  a  gap  in  bio- 
logical thought  and  study  has  resulted  in  consequence.     In  effect 
it  has  shorn  the  study  of  heredity  and  evolution  not  only  of  one  of 
its   most  important  branches,  but  of  its   main  title  to  practical 
utility  as  well.1 

36.  Nevertheless,  since  these  terms,  innate,  acquired,  and  inherit- 
able are  firmly  established  in  the  literature  of  heredity,  their  use 
is  now  in  many  ways  convenient.     For  the  sake  of  clear  thinking 
it  is  necessary,  however,  to  bear  their  real  meanings  carefully  in 
mind — to  remember  always,  when  speaking  of  multicellular  organ- 
isms, that  by  an  inborn  character  is  meant  one  which  develops 
under  the   stimulus  of  nutriment,  by  an  acquirement  one  which 
develops  under  the  stimulus  of  use  or  injury,  and  by  inheritance 
the   reproduction,  as  a  nutritional   character,  by  the  child  of  a 
parental  character  of  any  sort.     We  shall  thus  avoid  that  confusion 
of  thought  which   is  the  common  accompaniment  of  misleading 
terminology.     "  Men  believe  that  their  reason  rules  over  words ; 

1  See  chapters  xx.-xxv. 


20  THE  CHARACTERS  OF  LIVING  BEINGS 

but  it  is  also  the  case  that  words  react,  and  in  their  turn  use  their 
influence  on  the  intellect.  "  l 

37.  Though  the  terms  innate  and  acquired  are  misleading 
when  used  to  compare  or  contrast  the  characters  (which  have 
developed  under  different  stimuli)  of  the  same  individual,  they 
are  quite  accurate  when  used  to  compare  the  characters  of  different 
individuals.  Thus  when  we  say  that  an  individual  is  innately  like 
or  unlike  another  we  imply,  in  effect,  that  the  likeness  or  unlikeness 
is  due  to  a  germinal  similarity  or  dissimilarity.  On  the  other  hand 
when  we  say  that  the  individuals  agree  or  differ  in  their  acquire- 
ments, we  imply  that  the  stimuli  under  which  they  developed  have 
been  similar  or  dissimilar  in  kind  or  degree.  In  the  latter  case 
the  individuals,  as  compared  to  each  other,  have  eaten  more,  or 
less,  or  different  kinds  of  food,  taken  more,  or  less,  or  different 
kinds  of  exercise,  or  received  more,  or  less,  or  different  kinds  of 
injury. 

1  Bacon,  Novum  Organum,  i.  59. 


CHAPTER  II 

THE  METHOD  OF  DEVELOPMENT1 

The  adaptation  of  the  individual — The  method  of  adaptation — Variations — 
Modifications — Progression — Retrogression — The  recapitulation  of  the  life- 
history — The  opinions  of  embryologists. 


I 


38.  fNDIVIDUALS  \vho  survive  and  have  offspring,  especially 
if  they  have  a  full  quota  of  offspring,  must  necessarily 
have  been  well  fitted  from  first  to  last,  from  ovum  to  adult, 
to  their  surroundings.  The  changes  in  the  individual  during 
development,  especially  in  the  higher  animals,  are  very  great,  but, 
speaking  generally,  they  are  always  adaptive.  Thus  the  larva  of 
the  dragon-fly  which  inhabits  the  water  is  structurally  fitted  for  a  life 
in  it,  and  undergoes  an  adaptive  change  when,  as  perfect  insect, 
it  migrates  to  land.  Thus  again  the  human  embryo  in  the  womb 
is  fitted  to  an  environment  enormously  different  to  that  in  which 
life  is  possible  to  the  adult.  All,  or  almost  all,  the  changes  it 
undergoes  during  development  are  adaptive  also.  Offspring,  to 
survive  in  the  same  environments,  must  closely  resemble  their 
parents.  This  necessary  resemblance  is  secured  by  development 
along  similar  lines.  Step  by  step,  from  germ  to  adult,  the  child 
treads  in  the  developmental  footsteps  of  the  parent.  When,  as 
occasionally  happens,  the  recapitulation  of  the  parental  develop- 
ment is  not  fairly  close,  the  child  is  a  *  monster,'  out  of  harmony 
with  its  environment,  and  so  inevitably  perishes. 

39.  Though  every  normal  child  resembles  its  parent  as  a  whole, 
it  invariably  differs  in  details,  which,  though  innumerable,  are 
minute  as  compared  to  the  likenesses.  Thus,  though  the  normal 
offspring  of  a  human  being  is  always  another  human  being,  it  is 
never  an  exactly  similar  one.  These  differences,  when  innate 
(i.e.  germinal)  are  known  as  variations,  and  must  be  carefully  dis- 
tinguished from  differences  which  result  merely  from  an  unequal 
play  of  stimuli  (nutrition,  use,  injury,  etc.)  on  parent  and  child. 
The  latter  are  acquired  differences  or  modifications,  terms  which, 
as  we  have  seen,  are  also  used,  though  incorrectly,  to  distinguish 
1  See  Appendix,  §§  i-io. 


22  THE  METHOD  OF  DEVELOPMENT 

nutritional  characters  from  those  which  result  from  other  stimuli.1 
Small  variations  which  grade  into  one  another  are  termed  *  con- 
tinuous ' :  large  variations  ('  sports/  abnormalities,  congenital 
deformities,  '  mutations ')  are  termed  '  discontinuous.' 2  All 
variations,  all  differences  between  parent  and  child  due  to  differ- 
ences in  germ-plasms,  may  be  placed  in  one  or  other  of  two 
categories :  either  they  are  progressive,  or  they  are  retrogressive.  On 
progressive  variations  is  founded  progressive  evolution,  as  when 
the  wing  of  a  species  of  bird  undergoes  increase  in  size  or  power- 
On  retrogressive  variations  is  founded  retrogressive  evolution,  as 
when  the  wing,  owing  to  lessened  utility,  undergoes  subsequent 
decrease.3  An  extra  digit  on  the  hand  of  a  child  of  normal  parents 
is  an  example  of  progressive  variation  ;  a  missing  digit,  if  founded 
on  a  germinal  peculiarity,  not  on  a  mutilation,  is  an  example  of 
retrogressive  variation.  Of  course  any  given  variation  may  be  com- 
pound, consisting  of  both  progressive  and  retrogressive  variations. 
Thus  a  congenitally  malformed  digit  may  display  both  additions 
and  subtractions  when  compared  to  the  structure  in  the  parent. 

40.  Obviously,  since  the  child  treads  in  the  developmental  foot- 
steps of  the  parent,  since,  like  the  parent,  it  is  in  turn  germ,  embryo, 
foetus,  infant,  child,  youth,  and  adult,  a  progressive  variation 
implies  a  complete  recapitulation  of  the  parental  development  (as 
regards  the  particular  structure  or  character  that  has  varied),  plus 
an  additional  step ;  whereas  a  retrogressive  variation  implies  an 
incomplete  recapitulation,  one  or  more  of  the  steps  of  the  parental 
development  being  omitted.  The  line  of  thought  on  which  we 
are  now  engaged  is  so  very  essential  to  a  clear  understanding,  both 
of  evolution  and  heredity,  that  it  will  be  well  worth  the  reader's 
time  to  close  this  volume  for  a  space,  and  to  endeavour  to  think  of 
a  variation  which  is  neither  progressive  nor  retrogressive,  but 
something  else.  He  will  find  it  impossible.  If  he  then  tries  to 

1  The  reader  must  constantly  bear  in  mind   the  real,  or   at  least   the   more 
useful  distinction  between  variations   and  acquired  differences.     Obviously,  to 
take  an  example,  there  is,  between  two  men  one  of  whom  is  '  by  nature  '  lean, 
who  cannot  get  fat  no  matter  what  he  eats,  and  the  other  who  is  thin  merely 
because  he  is  starved,  a  difference  more  radical,  more  innate  than  that  between 
a  fat,  well-fed  man  and  one  who  has  been  starved,  but  would  get  fat  if  afforded 
the  opportunity. 

2  See  §§  249,  286. 

3  Sir  Ray  Lankester  has  objected  to  the  expression  '  retrogressive  evolution ' 
on  the  ground  that  retrogression  implies  an  exact  and  orderly  reversal  of  the 
antecedent  progression.     But  if  we  term  the  sum  of  progressive  variations  '  pro- 
gression,' it  appears  right  to  term  the  sum  of  retrogressive  variations  '  retrogres- 
sion.'    At  any  rate  I  cannot  find  a  better  term  and,  at  least,  my  meaning  is  clear. 


THE  RECAPITULATION  OF  THE  PARENT  23 

imagine  a  progressive  variation  which  is  not  a  prolongation,  a  step 
added  to  a  complete  recapitulation  of  the  parental  development,  or 
a  retrogressive  variation  which  is  not  an  abbreviation,  an  incom- 
plete recapitulation  of  the  parental  development,  he  will  fail  again. 

41.  Amongst  typical  unicellular  organisms  there  can,  of  course, 
be  no  recapitulation  of  the  kind  that  occurs  amongst  higher  types ; 
the  individual  divides  into  two  daughter-cells  which  resemble  itself 
and  which  separate  ;  there  is  no  development  of  a  cell-community, 
and  consequently  no  recapitulation  of  the  process  of  developing 
one.     But  with  multicellular  organisms  from  first  to  last  recapitula- 
tion must  have  been  the  sole  method  of  development.     It  is  the 
only   method    by   which    the   cell-community,   the   individual,   as 
distinguished  from  the  single  cell,  can  grow  into  the  likeness  of 
the  parent  community,  and  so  become  adapted  to  the  environment 
in  which  it  finds  itself.      Starting  from  the  same  point,  it  must 
follow  the  same  road  to  reach  the  same  goal.     The  typical  uni- 
cellular  organism,  on  the  other  hand,  treads  no   developmental 
footsteps  ;  it  remains  stationary  at  the  starting-point.     If  the  child 
of  a  man,  for  example,  did  not  recapitulate  the  development  of  his 
parent  he  would  be  a  *  monster.'     Monsters  are  known  to  us,  but, 
outside  mythology,  not  monsters  who  survive  and  have  offspring. 
Development  of  the  cell-community,  otherwise  than  by  recapitula- 
tion of  the  parental  development,  is  indeed  not  entirely  inconceiv- 
able ;  for  we  can  imagine  that  an  elephant,  for  instance,  may  give 
birth  to  a  mouse,  or  a  human  being  to  an  acorn.     But  it  never 
happens.      It  matters   not   in    the   least   whether  we  accept  the 
popular  doctrine  that  the  higher  types  were  specially  and  divinely 
created  as  highly  organized  cell-communities,  much  like  their  latest 
descendants,  or  whether  we  hold  the  scientific  theory  that  they  were 
derived  originally  from  lowly  unicellular  forms  of  which  the  germ- 
cell  is  the  modern  representative.     In  any  case  there  must  have 
been  recapitulation  of  the  parent  in  every  generation.1 

42.  But,   though,    in  the   case   of  individuals  who  themselves 
survive   and   have   offspring,  the   recapitulation    of  the   parental 
development   invariably    occurs,   it  is  not   necessarily — indeed  it 
never  is — quite  complete  nor  accurate.     The  child  varies  from  the 
parent  in  every  stage  of  development — as  embryo,  as  foetus,  and 

1  The  argument  is  not  affected  by  the  occurrence  of  what  is  known  as  alterna- 
tion of  generations,  by  the  budding  of  offspring  from  parents  which  have  arisen 
from  germ-cells,  nor  even  by  the  fact  that  parents  and  offspring  sometimes 
develop  differently  when  the  conditions  under  which  development  occurs  are 
different.  Under  similar  conditions  they  would  have  developed  along  similar 
lines.  See  §  92. 


24  THE  METHOD  OF  DEVELOPMENT 

as  infant,  as  well  as  in  the  adult  stage.  Progressive  variations, 
occurring  at  the  end  of  the  development,  add  to  the  parental  total 
of  development :  retrogressive  variations  subtract  from  it ;  both 
kinds,  occurring  during  development — interpolated  into  it — render  it 
inaccurate,  and,  in  the  process  of  many  generations,  very  inaccurate. 

43.  But,  if  the  child  recapitulates  the  development  of  the  parent, 
the  latter  also  recapitulated  that  of  the  grandparent,  who  in  turn 
recapitulated  that  of  the  great-grandparent,  and  so  on  up  to  the 
first  multicellular  ancestor.     Consider,  now,  the  simplest  conceiv- 
able  case   of    progressive    evolution    followed    by    retrogression. 
Imagine  a  line  of  individuals  A,  B  .  .  .  L,  M,  in  whom  a  structure 
undergoes  uninterrupted  increase  in  a  single  direction — as  it  were 
in  a  straight  line — by  successive  progressive  variations  occurring 
at   the   end    of  the  development   of  each   successive   individual. 
Suppose  the   structure  began  in  B  as  a  variation  from    A,  and 
underwent  evolution  by  successive  steps  in  C,  D,  .  .  .  till  it  reached 
its  culmination  in  M.     Suppose  also  that  it  began  to  retrogress  in 
N,  and  that  it  continued  to  do  so  uninterruptedly  till   it  quite 
disappeared  in  Z. 

44.  Consider  first  the  progression.    Clearly,  since  each  individual 
down  to  M  recapitulates  the  development  of  his  parent  and  makes 
in  addition  another  step,  the  development  of  B  must  consist  in  a 
recapitulation  of  A,  followed  by  his  own  variation.     C,  again,  since 
he  recapitulates  B,  must  first  recapitulate  A,  then  proceed  to  B's 
variation,  and  then  to  his  own.     D  in  turn  must  recapitulate  A, 
then  the  variations  in  order  of  B  and  C,  and  then,  and  then  only, 
proceed  to  his  own  variation.     M,  the  last  of  the  race  in  whom  a 
progressive  variation  occurs,   must  found  his  variation  on  a  re- 
capitulation of  A,  plus  a  recapitulation  in  orderly  succession  of  the 
variations  of  all  the  intervening   ancestors.     In  other  words  the 
development  of  the  structure  in  M  is  a  recapitulation  of  its  evolution 
in  the  race.     In  no  other  way  that  can  be  conceived  could  the 
structure   have   been    evolved.      Apply   this   reasoning    to   every 
structure  and  character   in  the  body,  and    we  perceive  that  the 
theory  that  every  individual  in  his  own  development  climbs  his 
own  genealogical  tree  must  necessarily  be  true.     Given  the  un- 
questionable fact  that  the  child  recapitulates  the  development  of 
the  parent,  any  method  of  development  other  than  by  a  recapitula- 
tion of  the  life-history  of  the  race  is,  not  only  impossible,  but 
actually  unthinkable.     One  truth  necessarily  involves  the  other. 

45.  But  to  say  that  development  is  a  recapitulation  of  the  life- 
history  is  one  thing.     To  say  that  in  every  instance  it  presents  a 


PROGRESSION  AND  RETROGRESSION  25 

complete  and  accurate  history  is  quite  another  thing.  On  the 
contrary,  since  variations  occur  in  every  stage  of  development,  in 
every  structure,  and  in  every  generation,  since  like  other  features  of 
the  germ-plasm  these  variations  may  be  persistent,  since,  therefore, 
they  tend  to  accumulate  during  the  passage  of  generations,  it  is 
certain  that  in  no  single  species  and  even  in  no  organ  or  structure 
is  recapitulation  complete  or  accurate.  The  structure  we  have  just 
considered  reached  its  culmination  in  M,  and  began  to  retrogress 
in  N.  Now,  obviously,  since  development  is  by  recapitulation,  N 
cannot  retrogress  except  by  an  act  of  incomplete  recapitulation  ; 
that  is  by  failing  to  reproduce  the  variation  by  means  of  which  M 
advanced  a  step  beyond  L.  Obviously  again  in  that  case  N  reverts 
to  L;  in  effect  he  is  L;  and  M,  unless  his  variation  becomes  latent, 
a  contingency  we  shall  consider  later,1  disappears  from  the  history. 
Of  course,  N's  act  of  retrogression  may  be  larger,  and  may  carry 
him  back  to  K  or  some  remote  ancestor,  say  F  or  E.  O's  retro- 
gressive variation  will  carry  him  yet  farther.  Z,  in  whom  retro- 
gression is  complete,  will,  in  effect,  be  A,  in  whom  the  structure  had 
not  even  its  beginnings.  In  all  M's  descendants,  therefore,  the 
recapitulation  will  be  incomplete.  Even  if  the  structure  be  evolved 
again  in  some  of  Z's  descendants  by  a  fresh  series  of  progressive 
variations,  it  will  still  be  incomplete.  A  chapter  of  the  life-history 
will  be  missing  even  though  one  like  it  be  added  subsequently. 

46.  For  the  sake  of  clear  thinking  it  must  be  noted  that  when 
we  allude  to  individuals  as  persisting  or  disappearing  from  the 
life-history,  we  are  using  a  mere  figure  of  speech.    As  we  have  seen, 
the  structures  of  offspring  are  not  derived  from  the  structures  of 
their  progenitors.     In  reality  we  are  considering  alterations  in  the 
germ-plasm,  which,  though  capable  of  change,  is  continuous  and 
potentially  immortal.     Germ-cells  are  unicellular  organisms,  with 
unicellular  germinal  descendants.     Multicellular  individuals,  as  we 
have  seen,  are  merely  episodes  in  the  unending  career  of  the  germ- 
plasm,  dwellings  which  it  periodically  builds  about  itself  and  from 
which  it  departs  as  they  tend  to  become  outworn.     To  be  precise, 
then,  the  alterations  in  the  germ-plasm  are  such  that  individuals 
recapitulate,  with  more  or  less  accuracy,  the  evolution  of  the  race 
of  individuals  that  spring  from  the  slowly  changing  germ-cells. 

47.  The   case  we   have   imagined — uninterrupted    progression 
followed  by  uninterrupted  retrogression — is  purely  ideal.     Really 
in   nature  progression   tends  to  alternate   irregularly  with  retro- 
gression.    Thus,  though  the  hand  of  every  child   tends  to  vary 

1  See  §§  186-9 ;  see  also  chapter  vii. 


26  THE  METHOD  OF  DEVELOPMENT 

somewhat  from  that  of  his  parent,  the  human  hand  has  not  altered 
appreciably  during  thousands  of  years.  Even  when  progression  or 
retrogression  ensues  as  a  whole,  individual  members  of  the  race 
may  reverse  the  process  temporarily.  Thus  B,  C,  D  may  exhibit 
progression  ;  E  retrogression,  through  reversion  to  C  ;  while  F  may 
resume  the  progression  and  so  resemble  D. 

48.  Moreover,  structures  possess  breadth  and  thickness  as  well 
as  length.     Their  progressions  and  retrogressions,  therefore,  are  in 
three  dimensions,   and   are   founded  on    a  number  of  variations, 
internal  and  external,  quantitative  and  qualitative,  which  is  practi- 
cally unlimited.     Each  of  these  variations  may  be  independent  of 
all  others  ;  even  single  cells  may  vary  independently  ;  so  that  while 
progression  is  occurring  in  some  respects,  retrogression   may  be 
occurring  in  others.     The  apparent  result,  if  we  think  of  the  struc- 
ture as  a  whole,  is  chaos.     But  we  are  able  to  avoid  the  seeming 
confusion    if  we   think   of  each   variation   separately.     We   then 
perceive  that  it  must  be  progressive  or  retrogressive,  that  it  must 
consist  in  a  prolongation  or  an  abbreviation  of  the  life-history  of  the 
part  as  presented  by  the  parent. 

49.  Lastly,  as  we  have  already  noted,  offspring  vary  from  their 
parents,  not  only  at  the  end  of  development,  but  during  the  course 
of  it — not  only  as  adults,  but  also  as  embryos.     Not  only  do  they 
add  sentences  (progressive  variations),  or  omit  sentences  (retro- 
gressive variations)  from  the  end  of  the  life-history  as  related  by 
the  parent,  but  they  interpolate,  or  omit,  or  alter  sentences  in  the 
body  of  the  work.     These  interpolated  progressive  and  retrogres- 
sive variations,  like  those  occurring  at  the  end  of  development, 
may  or  may  not  be  inherited  ;  that  is,  they  may  or  may  not  repre- 
sent persistent  changes  in  the  germ-plasm.     But  many  of  them  are 
persistent.     They  accumulate,  and  in  the  course  of  ages  so  alter  the 
life-history,  especially  in  its  earlier  parts,  which  have  longest  been 
exposed  to  change,  that  it  may,  and   usually  does,   become  un- 
recognizable.    Nevertheless  it  ever  remains  a  real  history,  a  real 
recapitulation,   though  in   part  a  recapitulation  of  past  error,  of 
additions  and  subtractions,  and  of  interpolations  which  are  com- 
pounded  of  both  additions  and    subtractions.     As    a   result,  the 
human  embryo,  for  example,  differs  so  greatly  from  its  prototypes 
of  the  life-history,  that  we  cannot,  with  any  degree  of  accuracy, 
trace   the   early  ancestry  of  our  race   by  watching  the  develop- 
ment of  the  individual.     At  first  it  is  unicellular ;  then  it  faintly 
resembles   very  low  multicellular   types;    next   it   reproduces   in 
succession,  more  and  more  clearly,  higher  and  higher  types  till  it 


THE  RECAPITULATION  OF  THE  EVOLUTION        27 

presents  the  appearance  of  an  ordinary  human  being.  But  mani- 
festly the  additions  and  subtractions  have  been  vast.  It  possesses, 
for  instance,  a  placenta,  an  organ  by  which  it  is  attached  to  the 
mother,  through  which  it  is  nourished,  and  which  at  one  time  is 
larger  than  the  embryo  itself;  but  which,  of  course,  could  not  have 
been  present  in  its  prototypes.  On  the  other  hand,  the  prototypes 
were  capable  of  maintaining  an  independent  existence  by  means 
of  functionally  active  organs,  which  the  embryo,  fitted  as  it  is  only 
for  a  passive  parasitic  life  within  the  uterus,  has  lost  or  almost 
lost.  Nevertheless  the  life-history  unfolded  by  the  child  is  just  as 
real,  just  as  complete,  and  probably  more  accurate  than  any  written 
chronicle  that  attempts  to  describe  the  whole  past  of  a  race. 

"  There  is  a  history  in  all  men's  lives 
Figuring  the  nature  of  the  times  deceased." 

50.  The  history  is  not  told  in  words,  but  in  graphic  signs,  in 
mimicry.  It  was  begun  by  the  first  multicellular  ancestor,  and 
then  consisted  of  a  single  word  or  sentence,  a  single  cell-division. 
Each  succeeding  generation  copied  it,  and  many  generations  added 
sentences.  But  the  copying  was  never  exact.  Therefore,  as  the 
history  lengthened  it  became  legendary  and  even  mythical  in  its 
earlier  parts — the  parts  which  have  been  longest  and  most  often 
copied  and  emended,  and  are  therefore  most  altered.  Doubtless, 
as  in  written  histories,  almost  every  embryonic  legend  and  myth 
is  founded  on  fact ;  but  it  is  as  hard  in  the  one  case  as  in  the  other 
to  dig  the  truth  from  the  concreted  mass  of  fiction.  In  some 
instances  the  earlier  history  is  not  represented  even  by  legend.  It 
is  entirely  lost,  as  in  the  case  of  plants  which  have  ceased  to 
propagate  by  seeds,  and  increase  only  by  means  of  detached 
portions  of  the  adult  individual,  such  as  buds  and  suckers.  In 
other  cases,  as  among  the  medusae,  whole  volumes  in  the  middle  of 
the  history  have  been  gradually  shortened  till  they  have  quite 
disappeared.1  In  all  cases,  if  the  individual  lives  to  complete  the 
story,  the  last  chapters  are  usually  very  full,  and  in  the  main 
exact — more  full  and  exact  than  any  written  history  can  be. 
Thus  the  offspring  of  the  human  being,  however  shortened  and 
altered  its  development,  however  vague  its  representation  of  its 
remote  ancestors,  is  always  another  human  being  who  reproduces, 
as  a  rule  with  wonderful  completeness,  all  the  immensely  complex 
details  that  go  to  the  making  of  a  man.  But  even  here,  as  in  a 

"  In  the  history  of  the  Hydroidae  any  phase,  planuloid,  polypoid,  or 
medusoid,  may  be  absent."  Dr  Strethill  Wright,  quoted  by  Darwin;  Animals 
and  Plants,  vol.  ii.  p.  364. 


28  THE  METHOD  OF  DEVELOPMENT 

written  history  of  a  recent  generation,  small  details,  unimportant 
variations  of  the  parent  from  the  grandparent,  are  often  omitted. 
Nature  is  careful  to  store  in  the  graphic  record  which  is  the  develop- 
ing body  of  the  individual,  only  those  facts  that  are  important  and 
significant,  only  those  variations  which  have  played  a  real  part  in 
the  evolution  of  the  race.  When  writing  her  history  she  concerns 
herself,  not  with  individuals,  but  with  populations ;  she  preserves, 
not  the  transient  details  of  individual  lives,  the  small  variations 
which  appear  in  the  parent  and  are  lost  in  the  child,  but  only 
those  great  and  enduring  general  movements  by  which  whole 
races  or  sections  of  races  have  differentiated  from  the  ancestral 
type.  And  her  aim  is  strictly  practical.  Her  history  of  ancestors  is 
told  for  the  benefit  of  descendants.  Therefore  even  great  general 
movements,  when  they  grow  remote,  are  eliminated  from  the 
record,  or  are  replaced  by  legend  and  myth  if  they  interfere 
with  the  smooth  tenor  of  the  narrative — if  they  interfere  with 
the  quick  development  of  the  child  along  the  shortest  and  simplest 
lines. 

51.  Hitherto  the  doctrine  of  recapitulation  has  been  accepted 
by  scientific  men  on  the  evidence  of  observed  likenesses  between  the 
embryos  of  the  higher  and  the  adults  of  the  lower  animals.  It 
has  not  yet  been  realized  that,  given  the  undisputed  facts  that  the 
organic  world  arose  by  evolution,  and  that  the  child  recapitulates 
the  parental  development,  any  method  of  development  other  than 
that  by  the  recapitulation  of  the  life-history  is  literally  incon- 
ceivable. When  Darwin,  succeeding  where  Lamarck,  Spencer, 
and  others  had  failed,  converted  a  sceptical  world  to  a  belief  in 
evolution,  these  vague  likenesses  were  held  to  furnish  the  strongest 
proof  in  existence  of  his  contention.  Recently,  however,  some 
embryologists,  deceived  by  the  frequent  unlikenesses,  have  denied 
the  recapitulation  of  the  life-history.  According  to  them  the 
resemblances  are  due  to  a  "sort  of  memory"  possessed  by  the 
embryo,  a  suggestion  which  may  possess  poetical  merits.  As  a 
fact,  we  should  know  the  doctrine  of  recapitulation  as  true  even  if 
an  embryo  resembling  a  lower  type  had  never  been  seen,  and  it 
had  been  ascertained  merely  that  the  embryos  of  different  genera- 
tions resembled  one  another  as  much  as  the  adult  individuals.  The 
function  of  an  embryologist  is  not  to  furnish  evidence  for,  or 
against,  a  necessary  truth  ;  but  to  ascertain  to  what  extent  this  or 
that  type  of  animal  or  plant  recapitulates  its  evolution  with  com- 
pleteness and  accuracy.  It  is  no  excuse  to  declare  that  only 
complete  and  accurate  recapitulation  has  been  denied.  No  one, 


SUMMARY  29 

having  even  an  elementary  acquaintance  with  the  facts,  has  alleged 
that  recapitulation  is  ever  other  than  incomplete  and  inaccurate. 
Thus  no  one  has  maintained  that  at  one  stage  of  human  develop- 
ment the  embryo  is  a  water-breathing  animal,  with  all  its  structures 
and  faculties  perfect,  or  that  the  ancient  prototypes  of  the  embryo 
swam  about  dragging  a  placenta  behind  them. 

52.  Summing  up  the  foregoing,  the  question  I  wish  to  place 
before  the  reader  is  this :  If  offspring  recapitulate  closely  but  not 
exactly  the  parental  development,  if  progression  always  implies  a 
complete  recapitulation  plus  an  addition,  and  retrogression  an 
incomplete  recapitulation  (with  a  step  or  steps  subtracted),  if 
through  all  the  ages  offspring  have  always  recapitulated  the 
main  features  of  parental  development,  is  it  possible,  or  even 
thinkable,  that  individual  development  can  be  anything  other  than 
a  recapitulation  of  the  life-history — not  an  exact  recapitulation,  but 
one  with  additions  and  subtractions  ? 


CHAPTER  III 
THE  METHOD  OF  SCIENCE 

Biological  sects  —  Facts  patent  to  our  senses  —  Facts  obscured  to  them  —  The 
function  of  laboratory  methods  of  inquiry  —  The  methods  by  which  the  facts  of  the 
various  sciences  are  observed  —  '  Exact  Methods  '  —  The  nature  of  science  —  The 
scientific  value  of  facts  —  The  mental  processes  by  means  of  which  facts  are  classified 
—  Hypotheses  and  theories  —  The  necessity  for  testing  thinking  —  The  method 
by  which  it  is  done  —  Induction  and  deduction  —  Laboratory  methods  when  used 
as  means  of  discovery  and  as  tests  for  thinking  —  The  common  neglect  of  tests  — 
The  essence  of  the  experimental  method  —  The  value  of  controversy  —  The  dis- 
tinction between  facts  and  theories  —  The  legitimate  and  illegitimate  uses  of 
deduction  —  The  contrasts  between  physical,  chemical,  and  biological  theories  — 
The  value  of  experiment  in  these  sciences  —  Laws  of  nature  —  Deduction  an  essential 
part  of  the  mental  processes  of  rational  beings. 


53-  fTTAHE  reasoning  by  which  we  have  demonstrated  that 
the  development  of  the  individual  is  a  recapitulation 
of  the  evolution  of  the  race,  is  in  some  measure  de- 
ductive. The  facts  from  which  we  started  our  thinking  have  all 
been  gathered  by  simple  observation.  Thus  the  fact  that  offspring 
tend  to  recapitulate  with  variations  the  parental  development  has 
been  simply  observed.  The  language  used  by  some  biological 
workers  indicates  an  opinion  that  deduction  is  illegitimate,  or  at 
least  unsafe.1  Others  maintain,  in  effect,  that  materials  furnished 
by  experiment,  or  some  such  aid  to  observation,  affords  the  only 
safe  basis  or  test  for  reasoning.2  The  points  thus  raised,  involv- 

1  The  statement  that  deduction  —  any  and  every  sort  of  deduction  —  is  con- 
sidered illegitimate  by  any  section  of  scientific  workers  may  be  received  with 
incredulity  by  people  who  are  aware  of  the  part  it  has  played  in  the  creation  of 
science.     An  acquaintance  with  medical  literature  and  thought  would  dispel  any 
doubt.     For  instance,  three  years  ago  there  was  published  a  large  work  (The  Food 
Factor  in  Disease,  by  Francis  Hare,  M.D.  ;  Longmans,  Green  and  Co.),  the  preface 
of  which  actually  consists  in  an  apology  for  the  use  of  the  method  —  an  apology 
for  testing  thinking.     The  book,  an  exceptionally  original,  thoughtful,  and  able 
one,  failed,  I  understand,  completely. 

2  "  The  recognition  that  only  by  experimental  methods  can  we  hope  to  place 
the  study  of  Zoology  on  a  footing  with  the  sciences  of  chemistry  and  physics 
is  a  comparatively  new  conception,  and  one  that  is  by  no  means  admitted  as  yet 
by  all  zoologists.   I  do  not  wish  to  disparage  those  studies  that  deal  with  the  descrip- 
tive and  the  historical  problems  of  biology.  They  also  afford  a  wide  field  for  activity, 
and  the  more  familiar  we  become  with  the  structure  and  modes  of  development 


BIOLOGICAL  SCHOOLS  31 

ing,  as  they  do,  questions  as  to  what  constitutes  valid  thinking  and 
what  reliable  evidence,  are  so  fundamentally  important  that  it  is 
necessary  to  consider  them  at  some  length. 

54.  Students  of  heredity  and  evolution  who  think  about,  as 
well  as  record,  the  facts  they  observe,  are  divided  into  schools, 
some  of  which  overlap ;  for  example,  the  selectionist,  the  muta- 
tionist,  the  Mendelian,  and  the  biometric.  If  these  divisions 
indicated  merely  associations  of  men  who  adopt  different  methods 
of  research,  then,  since  a  division  of  labour  is  advantageous  when 
dealing  with  a  subject  so  large  and  difficult,  the  existence  of 
schools  would  be,  not  only  harmless,  but  useful.  Differences  of 
opinion  could  then  be  settled  as  they  arose  by  a  comparison  and 
sifting  of  evidence.  But  unfortunately  the  separation  is  some- 

of  animals,  so  much  the  better  can  we  apply  the  experimental  method.  In  fact, 
many  of  the  problems  of  biology  only  become  known  to  us  as  the  result  of  direct 
observation.  The  wider,  therefore,  our  general  information,  the  greater  the 
opportunity  for  experimentation. 

"  It  is  undoubtedly  true  that  many  zoologists  who  have  spent  their  lives  in 
acquiring  a  broad  knowledge  of  the  facts  of  their  science  fail  to  make  use  of  their 
information  by  testing  the  very  problems  that  their  work  suggests.  This  is  owing, 
no  doubt,  to  their  exclusive  interest  in  the  observational  and  descriptive  sides 
of  biology,  but  also  in  part,  I  think,  to  the  fact  that  the  experimental  method 
has  not  been  sufficiently  recognized  by  zoologists  as  the  most  important  tool 
of  research  that  scientists  employ.  (T.  H.  Morgan,  Experimental  Zoology,  p.  3.) 

"  The  essence  of  the  experimental  method  consists  in  requiring  that  every 
suggestion  (or  hypothesis)  be  put  to  the  test  of  experiment  before  it  is  admitted 
to  a  scientific  status.  From  this  point  of  view  the  value  of  a  hypothesis  is  to  be 
judged,  not  by  its  plausibility,  but  by  whether  it  meets  the  test  of  experiment." 
(Op.  cit.t  p.  6.) 

"  It  is  sometimes  said  that  nature  has  already  carried  out  innumerable  and 
wonderful  experiments,  and  that  we  can  never  hope  to  excel  her  in  this  power. 
Is  it  not  better,  therefore,  to  examine  patiently  and  reverently  what  she  has 
done,  and  in  this  way  learn  how  her  processes  have  been  carried  out  ?  Let  us 
not  be  blinded  by  rhetorical  questions  of  this  kind.  No  doubt  nature  has  carried 
out  prodigious  experiments ;  but  we  can  never  be  certain  that  we  know  how  she 
has  obtained  her  results  until  we  repeat  the  process  ourselves.  What  would 
the  chemist  or  the  physicist  say  if  he  were  told  that  nature  has  already  carried  out 
experiments  on  a  much  greater  scale  than  he  can  hope  to  accomplish,  and  that 
he  should  drop  his  experimental  methods  and  study  his  physics  in  a  thunder- 
storm and  his  chemistry  in  an  eruption."  (Op.  cit.,  p.  8.) 

"  If  the  truth  must  be  told,  the  experimental  method  was  given  up  for  a  long 
time  by  the  majority  of  specialists  themselves  in  favour  of  the  controversial, 
and,  indeed,  this  tendency  has  by  no  means  yet  died  out  among  the  habits  of  some 
professed  evolutionists.  On  the  other  hand,  during  the  past  fifteen  to  twenty 
years,  a  few  scattered  workers  have  diligently  applied  themselves  to  the  study  of 
the  facts  of  variation  and  inheritance,  with  results  which  already  more  than 
justify  the  anticipation  in  which  their  work  was  begun — namely,  that  by  such 
methods  alone  can  any  real  progress  in  our  knowledge  of  the  processes  of  evolution 
be  brought  about."  (R.  H.  Lock,  Variations,  Heredity,  and  Evolution,  p.  3.) 


32  THE  METHOD  OF  SCIENCE 

times  more  radical.  Exactly  as  in  religion,  it  depends  largely  on 
the  fact  that  the  schools,  or  some  of  them,  value,  or  seem  to  their 
opponents  to  value,  evidence,  not  in  proportion  as  it  is  authentic 
and  relevant,  but  in  proportion  as  it  has  been  gathered  by  this  or 
that  process  of  inquiry. 

55.  Now,   of  course,   both   the  methods  of  thinking  and  the 
evidence  on  which  the  opinions  of  any  school  are  based  may  be 
altogether  wrong,  and,  therefore,  their  opponents  may  be  right  in 
refusing  to  use  them.     But,  in  that  case,  the  reasons  for  rejection 
should   be   set  out  plainly  and   precisely.      It  is  not  enough  to 
ignore  evidence,  or  stigmatize  thinking  as  '  deductive,'  or  '  philo- 
sophic,' or  '  obsolete.'    Epithets  are  very  unconvincing  to  opponents. 
A  reasoned  statement  ought  to  justify  what  in    its  absence  has 
the   appearance   of   mere   prejudice.      Otherwise,   in  the  lack  of 
common  criteria  for  facts  and  methods  of  thinking,  differences  of 
opinion  tend  to  become  as  irremovable  and  irrational  as  those  of 
religious  sects.     Scientific  men,  no  matter  how  open-minded,  are 
sure,  of  course,  to  differ  more  or  less  in  opinion,  for  they  differ  in 
knowledge  and  reflective  power ;    but  sectarian  differences  arise 
only  when  evidence  and  modes  of  thought  are  accepted  or  rejected 
on  improper  grounds. 

56.  In  the  present  chapter  I  shall  discuss  the  question  as  to 
what  kinds  of  evidence  and  processes  of  thought  are  permissible 
in  science.     Like  other  men,  I  belong,  more  or  less  exclusively,  to 
a  particular  school ;  but,  very  naturally,  like  them,  I  believe  I  am 
not  a  member  of  a  sect.     I  recognize,  however,  the  possibility  that 
I,  not  the  people  with  whom  I  disagree,  may  be  prejudiced ;  at 
any  rate  I  recognize  that  my  opinions  may  appear  as  prejudices  to 
opponents,  unless  I  first  demonstrate  that  the  facts  and  thinking 
on  which  they  are  founded  are  such  as  it  is  right  to  use.    Hereafter, 
since  I  shall  not  have  begged  the  question  by  merely  assuming 
that  certain  classes  of  facts  and   processes   of  thought  are  par- 
ticularly right  or  particularly  wrong,  but  shall  have  stated  explicitly 
the  grounds  for  my  convictions,  the  reader,  if  he  differs  from  me, 
will  at  least  have  it  in  his  power  to  indicate  exactly  and  easily 
where  and  how  I   am  mistaken.     If  he  finds  I  am  wrong  in  the 
present  chapter,  I  am  sure  he  will  be  wise  not  to  proceed  further ; 
for  it  is  not  possible  that  reasoning  that  is  based  on  initial  inac- 
curacies of  fact  or  thought  can  contain  anything  of  value.     How- 
ever, I  do  not  believe  he  will  think  me  mistaken.    He  may  wonder, 
indeed,  why  I  have  taken  the  trouble  to  write  the  chapter.      I  am 
tolerably  sure  that  all  of  it  will  seem  obviously  true  and  previously 


FACTS,  PATENT  AND  OBSCURED         33 

known  to  him  ;  but,  if  he  has  the  patience  to  read  the  rest  of  the 
book,  he  will  find  that  it  was  very  necessary.  In  numbers  of  recent 
publications  the  rules  of  ordinary  scientific  procedure  have  been 
broken,  and  the  breach,  so  far  from  being  admitted  as  a  fault,  has 
been  claimed,  explicitly  or  implicitly,  as  a  merit.  Even  a  cursory 
consideration  of  scientific  controversies  renders  it  evident  that  the 
fundamental  source  of  almost  every  disagreement  has  been  a 
neglect,  on  one  side  or  the  other,  to  conform  in  practice  with  that 
which  in  theory  is  regarded  as  a  truism.  Therefore,  if  we  can 
reach  a  preliminary  agreement  as  to  the  materials  for  thought  and 
modes  of  thought  which  it  is  legitimate  to  employ,  more  than  half 
of  the  causes  of  disagreement  will  be  eliminated  at  a  stroke.  At 
this  stage,  for  lack  of  illustrations  with  which  to  point  the  argu- 
ment, the  discussion  will  not  be  very  complete.  For  example,  I 
shall  find  it  impossible  to  demonstrate  that  masses  of  valuable 
evidence,  bearing  on  various  great  problems  of  heredity,  have  fre- 
quently been  ignored  without  valid  excuse.  But  throughout  the 
remainder  of  the  work  I  shall  indicate  illustrations  as  they  arise. 

57.  Some  facts — by  far  the  greater  number  of  facts  known  to 
us — are  patent  to  our  senses ;  that  is  to  say,  we  have  only  to  look, 
feel,  hear,  taste,  smell,  or  invoke  the  muscular  sense,  and  we  become 
aware  of  them.     It  is  the  function  of  our  senses  to  supply  us  with 
facts,  and  without  them  we  could  not  maintain  existence.     But 
other  facts  are  of  such  a  nature,  or  are  so  obscured  by  the  settings 
in  which  they  occur,  that  they  cannot  be  directly  observed  by  our 
senses,  or  inferred  from  the  evidence  supplied  by  them  with  any 
degree  of  certainty.     We   have,   then,   to   resort  to   experiment, 
biometry,  or  some  such  '  laboratory '  method,  to  render,  if  possible, 
these  obscured  facts  as  certainly  known  as  those  which  are  patent 
from  the  first.     When  used  for  purposes  of  discovery,  a  laboratory 
method  is  nothing  other  than  a  means  of  eliminating  obscuring 
conditions  and  so  making  hidden  facts  perceptible,  or  at  least 
capable  of  being  inferred  with  greater  certainty.     "  The  object  of 
experiment  is  to  eliminate  unessential  conditions  in  the  phenomena  ; 
.  .  .  when  complete  knowledge  of  the  essential  conditions  can  be 
obtained  by  observation,  experiment  is  unnecessary."  *     "  Experi- 
ment only  has  an  advantage  over  observation,  in  so  far  as  it  is 
capable  of  supplementing  the  usual  deficiencies  of  the  latter."2 

58.  The    ascertained    facts    of    some    sciences,    for    example, 
systematic  zoology,  botany,  anatomy,  and  geology,  are  almost  all 

1  Welton,  Manual  of  Logic,  vol.  ii.  p.  115. 

2  Lotze,  Logic,  Eng.  Trans.,  vol.  ii.  p.  40. 


34  THE  METHOD  OF  SCIENCE 

patent.  If  we  are  possessed  of  normal  faculties,  we  have  only  to 
observe  in  the  right  places  and  at  the  right  times  and  we  are  able 
at  once  to  note  them.  Experiment  would  be  useless  and  absurd, 
indeed  impossible,  here.  Thus  we  could  not  by  experiment  ascer- 
tain that  a  species  of  butterfly  was  winged  and  contained  several 
varieties.  There  could  have  been  no  such  sciences  as  zoology  and 
botany  had  we  depended  on  experiment.  Therefore  their  students 
have  relied  almost  exclusively  on  simple  observation.  The  right 
times  and  places  in  which  to  observe  may  be  hard  to  find,  but, 
once  found,  the  phenomena  can  be  noted. 

59.  In  other  sciences,  for  example,  physics  and  chemistry,  many, 
indeed  most  of  the  facts  are  obscured.     Thus  we  cannot  by  our 
unaided  senses  discover  the  composition  of  water  or  alcohol,  or  the 
way  in  which  gases  behave  under  pressure.     Therefore  physicists 
and  chemists  have  been  obliged  to  rely  very  largely  on  experiment. 

60.  The  study  of  heredity,  which  draws  its  materials  from  every 
science  that  deals  with  life,  stands  midway.     Here  the  laboratory 
cannot  create  a  science  ;  it  can  only  help  to  create  one.     Most  of 
what  we  know  about  life  is  patent  to  our  senses  and  can  be  simply 
observed.     Especially  is   this   the   case  with    regard   to  facts   ot 
structure,  for  example,  the  shape,  size,  and  anatomical  relations  of 
the  parts  of  an  animal.     But  some  facts,  especially  those  relating 
to  function  (e.g.  the  function  of  the  thyroid  gland),  are  obscured,  and 
to  discover  them,  if  it  be  possible,  we  must  resort  to  a  laboratory 
method.     Therefore,  if  we  say,  or  imply  that  facts  supplied  by 
simple  observation  are   useless   to  the   students  of  heredity,  we 
declare,  in  effect,  that  most  facts  relating  to  structure  and  many 
relating  to  function  are  useless — we  declare,  in  effect,  that  when 
studying  heredity  we  must  not  draw  our  facts  from  systematic 
zoology,  botany,  comparative  anatomy,  embryology,  palaeontology, 
indeed  most  sciences  that  deal  with  life. 

61.  In  contradistinction  to  simple  observation,  the  laboratory 
methods  of  inquiry  have  sometimes  been  termed   '  exact ' ;  but, 
very  obviously,  the  term,  implying  as  it  does  that  simple  observation 
is  necessarily  less  exact,  is  erroneous.     They  are  especially  exact 
on  particular  occasions  only.     For  example,  we  do  not  need  them 
to  make  us  entirely  sure  that  men  resemble  apes  physically  more 
than  they  do  other  animals,  that  the  offspring  of  human  beings 
are  human,  that  every  generation  follows  closely  but  not  exactly 
in  the  developmental  footsteps  of  the  one  that  precedes  it,  that  the 
forms  of  life  which  have  inhabited  the  earth  have  changed  with  the 
geological  epochs,  that  stags  have  antlers  and  elephants  have  tusks, 


LABORATORY  METHODS  OF  INQUIRY  35 

that  Englishmen  are  on  the  average  fairer  than  negroes  and  taller 
than  African  pigmies,  and  so  on  as  regards  millions  of  facts. 

62.  On  the  other  hand,  we  cannot  without  the  experiment  of 
weighing  discover  the  precise  weight  of  a  stag,  nor  without  biometry 
the  exact  degree  in  which  Englishmen  are  on  the  average  fairer 
than  negroes  and  taller  than  pigmies.     In  a  sense,  of  course,  the 
statement,  for  example,  that  Englishmen  are  on  the  average  exactly 
so  many  inches  and  fractions  of  an  inch  taller  than  pigmies  is  more 
precise  than  the  bare  statement  that  they  are  taller ;  but  only  in  a 
sense.     For  the  one  statement  is  not  truer,  but  only  contains  more 
of  truth  than  the  other.     That  is,  it  is  more  detailed.     Obviously, 
whether  or  not  the  additional   details  are  needed  in  any  given 
inquiry,  depends  on  circumstances.     They  are  not  always  needed. 

63.  Beyond  question,  biological  facts  discovered  in  the  labora- 
tory are  often    very  valuable — as  valuable  as  any  other  verified 
facts,  and  on  particular  occasions  more  valuable  because  designedly 
discovered  with  a  view  to  fill   gaps  which  prevent  the  linking 
together   of  facts    already   known.     There    is,   however,   nothing 
especially  magical,  scientific,  or  accurate  in  data  obscured  to  our 
senses  till  revealed  by  a  laboratory  inquiry.     Such  an  inquiry  can 
do  no  more  than  render  them  as  patent,  but  no  more  patent  than 
the  majority  of  facts  on  which  our  knowledge  of  living  beings  is 
based.     The  latter  class  of  facts,  indeed,  are  usually  more  capable 
of  easy  verification   than  any  discovered  in  the   laboratory.     In 
noting   them    we  have  only  to  guard  against  errors  of  observa- 
tion, not  also  against  errors  in  experimenting.     If  the  reader  will 
think  over  the  evidence  on  which  I  shall  draw  for  the  purposes  of 
the  present  volume,  I  believe  he  will  conclude  that,  if  any  of  it 
bears  a  doubtful  aspect  to  his  mind,  it  is  that  large  mass  which  has 
been    furnished   by  laboratory  inquiry ;    for,    while   some  of  the 
latter  is  controverted,  and    all  of  it  must  be  accepted  by  most 
people  at  second  hand,  nearly  all  the  rest  is  indisputably  true,  as 
he  will  know  from  his  own  experience  of  life. 

64.  Sometimes  it  is  said  that  we  must  make  biology  an  exact 
science  by  imitating  the  methods  of  physicists  and  chemists — by 
which  is  meant  that  we  must  experiment,  or  compile  statistics.     It 
is  right  that  we  should  do  both  when  necessary ;    but,   plainly, 
physics  and  chemistry  are  exact  sciences,  not  because  the  facts  on 
which  they  are  based  are  obscured  and  have  to  be  laboriously  dis- 
covered by  laboratory  methods,  but  because  they  deal  with  data 
that  are  capable  of  being  exactly  measured,  and  because  physicists 
and  chemists  have  had  both  the  means  and  the  will  to  test  their 


36  THE  METHOD  OF  SCIENCE 

thinking  exactly.1  Mathematics,  which  is  not  an  experimental 
science,  is  exact  for  similar  reasons.  The  study  of  heredity  is  not, 
and  cannot  be,  exact  in  the  same  sense,  for  no  two  individuals, 
nor  even  two  of  their  cells,  are  ever  precisely  alike.  When  we 
unite  a  given  quantity  of  oxygen  with  a  given  quantity  of  hydrogen, 
the  result,  which  can  always  be  predicted  with  absolute  confidence, 
is  ever  a  definite  quantity  of  water  of  a  definite  composition.  But, 
when  two  germ-cells  are  united,  it  is  impossible  to  foresee  the 
exact  nature  of  the  product.  Doubtless,  when  dealing,  not  with 
individuals,  but  with  populations,  biometry,  the  statistical  method 
of  investigating  the  phenomena  of  life,  does  in  some  cases  enable 
us  to  forecast  the  future  with  considerable  accuracy ;  but  this 
accuracy  is  infinitely  less  comprehensive  than  that  obtained  in 
physics  and  chemistry  where  predictions  are  true,  not  only  as 
regards  averages,  but  also  as  regards  particular  instances.  It  is 
conceivable,  though,  owing  to  the  complexity  of  the  conditions,  not 
at  all  probable,  that  biologists  will  one  day  be  able  to  predict 
with  the  same  accuracy  and  confidence  as  physicists  and  chemists  ; 
but  it  is  hard  to  understand  how  this  goal  will  be  the  sooner 
attained  by  ignoring  everything  that  is  patent  to  our  senses. 
Physicists  and  chemists,  as  rational  beings,  would  be  happy  if 
their  facts  were  patent,  and  they  were  thus  spared  some  of  the 
labours  of  the  laboratory.  It  is  their  good  fortune,  not  their  merit, 
that  they  are  able  to  measure  and  test  exactly. 

65.  In  brief  terms,   sciences  are   experimental  or  non-experi- 
mental in  proportion  as  the  facts  on  which  they  are  founded  are, 
or  are  not,  obscured.      They  are  exact  or  inexact  in  proportion  as 
they  are,  or  are  not,  capable  of  being  founded  on  precise  measure- 
ments.    Some  sciences  are  both  experimental  and  exact ;  but  the 
two  circumstances  have  no  necessary  relation.     Dogs  run  and  wag 
their   tails.      But   they   do  not  run  because  they  wag  their  tails. 
Neither  are  sciences  exact  because  they  are  experimental.     In 
science,  as   in  the  ordinary  affairs  of  life,  a  source  of  error  as 
common  as  or  more  common  than  the  use  of  inaccurate  data,  is  a 
neglect  to  use  the  whole  of  the  facts  available.     Certainly  the  use 
of  all  the  evidence  is,  through  the  exposure  of  discrepancies,  one 
of  the  most  effective  means  of  ascertaining  whether  any  of  it  is 
inaccurate  or  has  been  misinterpreted. 

66.  Science  is  founded  on  facts.     But  collections  of  facts  do 
not  by  themselves  constitute  science.     They   are   only  the  raw 
materials  out  of  which  it  is  manufactured.      Science  consists  in  the 

1  See  §  824. 


THE  NATURE  OF  SCIENCE  37 

classification,  the  systematization  of  facts.  When  we  classify 
facts,  we  indicate  their  relations  one  to  another ;  in  other  words, 
we  interpret  them  in  terms  of  one  another.  Therefore,  not  only 
observation,  but  thought,  is  necessary.  "  The  classification  of 
facts,  the  recognition  of  their  sequences  and  relative  significance, 
is  the  function  of  science."  x  "  The  goal  of  sciencejis  clear — it  is 
nothing  short  of  the  complete  interpretation  of  the  universe."  2 
"There  is  no  way  to  gain  a  knowledge  of  the  universe  except 
through  the  gateway  of  the  scientific  method.  The  hard,  stony 
path  of  classifying  facts  and  reasoning  upon  them  is  the  only  way 
to  ascertain  truth."  3  "  We  must  never  forget  that  it  is  principles, 
not  phenomena — the  interpretation,  not  the  knowledge  of  facts — 
that  are  the  objects  of  inquiry."  4  "  The  world  only  becomes  in- 
telligible when  it  is  conceived  as  a  systematic  unity,  the  elements 
of  which  are  throughout  in  necessary  relation  to  each  other.  The 
attainment  of  knowledge  is  nothing  but  the  more  thorough  and 
complete  determination  of  these  relations.  Hence,  every  element 
of  reality  is  understood  just  to  the  extent  to  which  its  necessary 
relations  to  other  elements  are  grasped.  No  doubt  reality  as 
presented  to  us  is  infinitely  complex,  and  consists  of  various 
phenomena  which  resemble  each  other  generally,  yet  differ  in- 
definitely in  detail.  But  every  postulate  of  knowledge  compels  us 
to  think  every  variation  and  every  detail,  even  the  smallest,  as  so 
determined  by  conditions  that,  under  the  circumstances,  it  could 
not  possibly  be  other  than  it  is."  5  "  Scientific  thought  does  not 
mean  thoughts  about  subjects  with  long  names.  There  are  no 
scientific  subjects.  The  subject  of  science  is  the  human  universe  ; 
that  is  to  say,  everything  that  has  been  or  may  be  related  to 
man."  6 

67.  As  there  are  no  scientific  subjects,  so  there  are  no  scientific 
facts.  There  are  only  facts  which  have,  or  have  not,  been  used  in 
science — which  have  or  have  not  been  systematically  classified. 
We  have  only  to  think  of  our  houses  and  friends,  of  our  general 
surroundings,  to  recall  countless  facts  quite  as  indisputably  true 
as  any  that  have  been  incorporated  into  science,  but  which,  owing 
to  our  deficiencies,  are  not  as  yet  facts  for  science  ;  for  though  each 
of  us  seeks  to  classify  these  everyday  facts  in  such  a  way  as  will 
enable  him  to  move  in  comfort  and  security  in  his  world,  yet  we 
cannot  link  them  together  in  such  categories  as  will  enable  man- 

1  Pearson,  Grammar  of  Science,  ed.  1900,  p.  6.  2  Op.  cit.,  p.  14. 

3  Op.  cit.,  p.  17.  4  Herschel,  Natural  Philosophy,  §  10. 

6  Welton,  Manual  of  Logic,  vol.  ii.  p.  188.  6  Clifford,  Essays,  p.  86. 


38  THE  METHOD  OF  SCIENCE 

kind  in  general  to  interpret  nature  in  that  systematic  way  that 
constitutes  science. 

68.  The  scientific  value  to  us  of  a  fact  depends,  first,  on  our 
power  to  verify  it,  to  make  ourselves  and  other  people  sure  that  it 
is  a  fact ;  and,  second,  on  our  power  to  classify  it,  to  recognize  its 
relations  to  other  bodies  of  verified  evidence.  All  classification  is, 
in  essence,  a  process  of  reasoning,  of  interpreting.  If,  armed  with 
a  note-book,  I  went  into  the  world  and  jotted  down  accurate  state- 
ments concerning  the  individual  animals  and  plants  I  happened 
to  meet,  my  collection  of  facts  would  not  constitute  science.  But 
if,  with  their  help,  I  were  able  to  classify  living  beings  into  species, 
orders,  genera,  and  kingdoms,  my  facts  would  become,  what  they 
were  not  before,  foundations  of  science.  During  the  process  of 
classification,  as  I  passed  from  individuals  to  varieties,  and  from 
the  latter  to  species,  and  so  on,  my  descriptions  would  become 
more  and  more  brief,  simple,  and  generalized.  Instead  of  describ- 
ing many  individuals  I  would  describe  a  single  variety ;  instead  of 
describing  many  varieties,  I  would  describe  a  single  species,  and  so 
on.  But,  since  a  knowledge  of  species  involves  a  knowledge  of 
varieties,  which,  in  turn,  involves  a  knowledge  of  individuals,  each 
step  in  this  simplification,  this  classification,  would  involve  the 
manipulation  of  larger  and  more  complex  masses  of  facts,  and, 
therefore,  more  complex  thinking.  But,  as  long  as  my  facts  were 
properly  verified  and  classified,  neither  they  nor  the  processes  of 
thought  involved  would  grow  any  the  less,  or  more,  scientific  for 
being  more  complex.  If,  from  the  data  I  had  gathered,  I  were 
able  to  formulate  a  theory  of  evolution,  I  should  classify  an 
immense  body  of  facts  in  a  new  way  that  would  involve  very  far- 
reaching  and  complex  thought. 

69.  Obviously,  however,  the  complexity  of  the  mental  processes 
involved  in  classification  does  not  depend  wholly,  or  even  mainly, 
on  the  number  of  facts  to  be  classified  ;  for,  however  numerous  the 
facts,  their  relations  may  be  apparent  on  the  surface.  In  many 
cases,  we  have  only  to  discover  the  facts,  and  they  fall,  by  them- 
selves as  it  were,  into  the  right  categories.  Thus  in  anatomy, 
though  the  mass  of  facts  is  large,  and  the  discovery  of  some  of 
them  may  be  difficult,  it  is  comparatively  easy  to  describe  the 
bones,  ligaments,  nerves,  and  the  rest,  and  state  their  anatomical 
relations.  It  is  different  with  such  a  study  as  heredity.  Here  the 
relations  between  the  facts  are  not  easy  to  trace,  and  the  mental 
processes  involved  in  classification  are  correspondingly  complex 
and  subtle.  Thus,  suppose  a  strong  and  athletic  man,  who  has 


HYPOTHESES  AND  THEORIES  39 

good  health  and  takes  plenty  of  exercise  and  nourishing  food, 
has  a  son  resembling  himself,  then  what  is  the  relation  between 
the  facts?  To  what  shall  we  attribute  the  likeness  between 
father  and  son  ?  Is  the  son  strong  and  healthy  merely  because  he 
was  'born'  with  the  characteristics  with  which  the  father  was 
'  born/  and  because  he  has  lived  like  him  ?  Or  has  the  life  led  by 
the  father  altered  the  germ-plasm  and  improved  the  child's  heritage  ? 
Or  are  both  factors  to  be  taken  into  account  ?  Obviously,  our  task 
in  ascertaining  the  relations  between  the  facts  is  harder  here  than 
in  anatomy.  We  are  obliged  to  draw  a  '  mediate '  inference.  The 
immense  number  of  erroneous  and  discarded  hypotheses  with  which 
the  past  of  heredity  is  littered  is  evidence  of  the  difficulty  found  by 
its  students  in  drawing  correct  inferences.1 

70.  An  inference  is  a  hypothesis.  But  at  first  it  is  only  a 
working  hypothesis,  a  mere  guess.  Before  we  can  be  sure  it  is  true, 
before  we  can  convert  it  into  an  established  theory -,  we  must  test  the 
thinking  by  which  it  was  reached,  and  so  ascertain  whether  it  is 
correct.  Now  there  is  one  way,  and  one  way  only,  by  which  the  truth 
of  hypotheses  can  be  tested.  As  we  test  facts  by  appealing  to  facts, 
so  we  must  test  thoughts  by  appealing  to  thoughts — to  inferences. 
We  must  proceed  by  two  steps.  First,  we  must  make  a  rigorous 
deductive  inference  of  consequences.  Next,  we  must  ascertain  by 
an  appeal  to  reality  in  the  world  around  us  whether  these  predicted 
consequences  actually  do  occur.2  For  example,  when  families 
dwell  under  unhealthy  conditions,  as  in  the  slums  of  great  cities, 
the  parents  tend  to  be  sickly  and  the  children  puny.  In  this  case 

1  The  necessity  of  adopting  diverse  methods  when  observing  and  classifying 
the  facts  of  the  various  sciences  is  hardly  realized  by  some  students.     Occasionally 
one  hears  an  anatomist,  zoologist,  or  botanist,  a  '  systematist,'  lament  the  rage  for 
speculation  and  declare  that  the  function  of  science  is  merely  to  observe  and 
classify  facts — by  which  is  meant  of  course  the  kind  of  observing  and  classifying 
that   is  usually  adequate   for   the  purposes  of  the  systematic  sciences.       But, 
obviously,  such  observing  would  be  of  little  use  to  the  chemist,  and  such  classifying, 
when  applied  to  a  subject  so  abstruse  as  heredity,  would  totally  fail  to  establish 
the  relations  between  the  facts.     The  difficulty  of  simply  observing  compels  the 
chemist  to  experiment ;    the  difficulty  of  classifying  compels  the  student  of 
heredity  to  speculation,  which,  however,  when  founded  on  strictly  ascertained 
facts  and  rigorously  tested  by  a  deductive  inference  of  consequences,  is  not  un- 
scientific, but  merely  an  especially  strenuous  effort  to  think  accurately — to  classify 
correctly.     See  §§  819  et  seg. 

2  "  Every  hypothesis  is  an  attempt  to  find  meaning  in  observed  phenomena, 
to  constitute  reality  in  a  rational  way.     It  follows  that  the  fundamental  condition 
of  a  valid  hypothesis  is  that  it  should  explain  and  give  meaning  to  the  facts  of 
observation.     And  it  can  only  do  this  if  it  embraces  those  facts  in  that  systematic 
whole  which  is  the  one  form  under  which  it  is  possible  to  think  the  universe.     This 


40  THE  METHOD  OF  SCIENCE 

we  have  a  choice  between  two  hypotheses,  two  inferences,  two 
statements  of  what  may  be  the  relations  between  the  phenomena. 
First,  we  may  infer  that  parental  ill-health  tends  to  injure  the 
germ-plasm,  and,  therefore,  that  the  children  are  innately  puny, 
innately  incapable  of  becoming  robust.  If  this  hypothesis  is  true, 
then  it  follows  as  a  necessary  consequence  that,  if  the  children  con- 
tinue to  dwell  in  the  unhealthy  environment,  the  weakened  germ- 
plasm  will  be  still  more  injured  and  the  grandchildren  will  be  still 
more  puny,  and  therefore  that  the  race  will  degenerate  step  by 
step.  At  any  rate,  if  it  can  be  shown  that  races  become  innately 
degenerate  under  such  conditions,  the  hypothesis  may  be  regarded 
as  a  theory  the  truth  of  which  has  been  established.  Here, 

(a)  The  facts  are  that  the  children  of  unhealthy  parents  are  very 
frequently  puny. 

(&)  The  hypothesis^  the  induction,  is  that  parental  ill-health  tends 
to  injure  the  germ-plasm,  and  so  render  the  children  and  their 
descendants  innately  puny. 

(c)  The  deduced  consequences  are  that  families,  classes,  and  races, 
exposed  to  unhealthy  conditions,  tend  to  become  degenerate. 

(d)  The  appeal  to  reality  is  the  ascertaining  whether  populations 
exposed  to  unhealthy  conditions  actually  do  become  degenerate. 

By  this  means  we  test  our  thinking,  our  hypothesis.  Second,  we 
may  infer  that  the  puniness  of  the  children  is  due,  not  to  the 
deterioration  of  the  germ-plasm,  but  merely  to  inferior  development 
resulting  from  the  unhealthy  conditions  to  which  the  children 
themselves  are  exposed.  That  is,  we  suppose  that  the  puniness  is 
not  innate.  If  this  second  hypothesis  is  true,  the  race  will  not 
grow  degenerate  through  being  exposed  to  unhealthy  conditions. 
On  the  contrary  it  will  become  more  resistant  to  those  conditions 
through  the  weeding  out  of  the  naturally  less  resistant  individuals. 
Having  drawn  these  two  contradictory  inferences,  we  have,  as  I 
say,  to  ascertain  which  of  them  is  true  by  appealing  to  reality  in 
the  world  around  us.1 

general  condition,  then,  may  be  considered  as  involving  three  subordinate 
conditions : — 

(1)  That  the  hypothesis  be  self-consistent,  and  in  harmony  with  all  the  other 
Jaws  included  in  the  conceived  system  of  reality. 

(2)  That  it  furnish  a  basis  for  rigorous  deductive  inference  of  consequences. 

(3)  That  these  inferred  consequences  be  in  agreement  with  reality. 

Of  these  conditions  the  first  two  are  applicable  to  the  formation  of  every 
hypothesis,  no  matter  how  provisional  a  character  it  may  have  ;  the  third  is  a 
condition  of  the  acceptance  of  a  hypothesis  as  true."  (Welton,  Manual  of  Logic, 
vol.  ii.  pp.  95-6.) 

1  See  §  733. 


THE  TESTING  OF  HYPOTHESES  41 

71.  It  is  obligatory  that  we  make  this  deductive  appeal  to  reality. 
When  it  is  done,  certain  facts — all  we  find  it  possible  to  employ  in 
this  way — are  used  as  the  basis  of  the  hypothesis.  Next  other  facts 
— all  the  rest  which  are  relevant  and  known  to  us — are  used,  in  as 
many  ways  as  possible,  to  test  the  truth  of  the  hypothesis.  The 
latter  class  of  facts  are  usually  much  the  more  numerous.  In  brief, 
we  found  the  hypothesis  on  certain  relevant  facts  and  prove  it  by 
means  of  the  rest.  In  this  way  only,  especially  when  we  are 
engaged  in  the  elucidation  of  some  obscure  and  difficult  matter,  is 
it  possible  to  use  all  the  facts.  If  we  do  not  proceed  thus — first 
formulating  our  hypothesis,  next  making  a  rigorous  deductive 
inference  of  consequences,  and  lastly  appealing  to  reality  for  con- 
firmation— our  thinking  is  mere  guessing.  A  hypothesis  is  quite 
valueless  to  science  unless  it  permits  a  deductive  appeal  to  reality, 
and  quite  unproved  until  it  has  been  found  to  stand  that  test. 
"The  sole  condition  to  which  we  need  conform  in  framing  any 
hypothesis  is  that  we  both  have  and  exercise  the  power  of  inferring 
deductively  from  the  hypothesis  to  the  particular  results,  which 
are  to  be  compared  to  known  facts."  1  No  scientific  worker,  that 
was  not  a  mere  observer,  has  ever  done  great  work  who  did  not  so 
test  his  hypotheses ;  no  hypothesis  has  ever  been  permanently 
included  in  science  but  has  been  so  tested.  "  If  it  be  an  advantage 
for  the  discoverer  of  truth  that  he  be  ingenious  and  fertile  in 
inventing  hypotheses  which  may  connect  the  phenomena  of  nature,  it 
is  indispensably  requisite  that  he  be  diligent  and  careful  in  com- 
paring his  hypotheses  with  the  facts,  and  ready  to  abandon  his 
invention  as  soon  as  it  appears  that  it  does  not  agree  with  the 
course  of  actual  occurrences.  This  constant  comparison  of  his 
own  conceptions  and  supposition  with  observed  facts  under  all 
aspects  forms  the  leading  employment  of  the  discoverer;  this 
candid  and  simple  love  of  truth,  which  makes  him  willing  to 
suppress  the  most  favourite  production  of  his  own  ingenuity  as  soon 
as  it  appears  to  be  at  variance  with  realities,  constitutes  the  first 
characteristic  of  his  temper.  He  must  have  neither  the  blindness 
which  cannot,  nor  the  obstinacy  which  will  not,  perceive  the 
discrepancy  of  his  fancies  and  his  facts.  He  must  allow  no  indol- 
ence, or  partial  views,  or  self-complacency,  or  delight  in  seeming 
demonstration,  to  make  him  tenacious  of  the  schemes  which  he 
devises,  any  further  than  they  are  confirmed  by  their  accordance 
with  nature.  The  framing  of  hypotheses  is,  for  the  inquirer  after 
truth,  not  the  end,  but  the  beginning  of  his  work.  Each  of  his 
1  Jevons,  Principles  of  Science,  p.  265. 


42  THE  METHOD  OF  SCIENCE 

systems  is  invented,  not  that  he  may  admire  it  and  follow  it  in  all 
its  consistent  consequences,  but  that  he  may  make  it  the  occasion 
of  a  course  of  active  experiment  and  observation.  And  if  the 
results  of  this  process  contradict  his  fundamental  assumptions, 
however  ingenious,  however  symmetrical,  however  elegant  his 
system  may  be,  he  rejects  it  without  hesitation.  He  allows  no 
natural  yearnings  for  the  offspring  of  his  own  mind  to  draw  him 
aside  from  the  higher  duty  of  loyalty  to  his  sovereign,  Truth :  to 
her  he  not  only  gives  his  affections  and  his  wishes,  but  strenuous 
labour  and  scrupulous  minuteness  of  attention."  * 

72.  In  science,  therefore,  we  must  not  only  use  words  that 
express  our  meanings  unmistakably,2  we  must  not  only  verify  our 
facts,  but  we  must  always  test  our  thinking  deductively  "  by  observ- 
ing the  present  state  of  the  world,  by  assiduously  studying  the 
history  of  past  ages,  by  sifting  the  evidence  of  facts,  by  carefully 
combining  and  contrasting  those  which  are  authentic,  by  generaliz- 
ing with  judgment  and  diffidence,  by  perpetually  bringing  the 
theory  we  have  constructed  to  the  test  of  new  facts,  by  correcting 
or  altogether  abandoning  it,  according  as  the  new  facts  prove  it  to 
be  partially  or  fundamentally  unsound."  3  All  this  is  axiomatic, 
and  has  been  axiomatic  since  men  began  to  think  scientifically. 
Therefore  it  would  be  difficult  to  conceive  anything  more  absurd 
than  the  statement  that  we  must  eschew  deduction  and  rely  wholly 
on  induction.  "  All  inductive  reasoning  is  but  the  inverse  applica- 
tion of  deductive  reasoning.  Being  in  possession  of  certain 
particular  facts  or  events  expressed  in  propositions,  we  imagine 
some  more  general  proposition  expressing  the  existence  of  a  law 
or  cause  ;  and  deducing  particular  results  of  that  supposed  general 
proposition,  we  observe  whether  they  agree  with  the  facts  in 
question."  4  Induction  and  deduction  "  differ  only  as  the  road  by 
which  we  ascend  from  a  valley  to  a  mountain  does  from  that  by 
which  we  descend  from  the  mountain  to  the  valley,  which  is  no 
difference  of  road,  but  only  a  difference  in  the  going."  5  Induction  is 
that  process  by  which  we  infer  a  generalization  from  a  consideration 
of  particular  facts  or  from  a  consideration  of  inferior  inductions, 
each  of  which  is  then  used  as  a  fact.  Thus  it  is  an  induction  which 
has  been  drawn  a  thousand  times  that  parental  ill-health  results  in 
innately  enfeebled  offspring.  It  is  also  a  common  induction  that 
it  has  no  such  effect  on  offspring.  Deduction  is  the  process 

1  Whewell,  Novum  Organum  Renovatum,  pp.  80- 1. 

2  See  chapter  i.  3  Macaulay. 

4  Jevons,  Principles  of  Science,  p.  265.  6  Port  Royal  Logic,  p.  314. 


THE  USES  OF  EXPERIMENT  43 

by   which   we   test   the  truth  of  our   inductions.     Obviously,    we 
cannot  test  the  truth   of  either  of  the  foregoing  inductions,  nor 
decide  between  them,  unless  we  appeal  deductively  back  again  to 
the  facts  of  the  world  around  us.     Experiment  is  one  of  the  ways 
in  which  we  may  test  an  inference.     After  we  have  considered  a 
collection  of  facts  and  drawn  an  induction,  we  say  to  ourselves, 
"  If  our  hypothesis  is  true,  if  we  have  thought  correctly,  such  and 
such  consequences  must  follow  "  ;  and,  if  possible,  we  experiment  to 
ascertain  if  they  do  follow.     If  they  do  actually  follow,  then  there 
is  a  high   probability   that   our   hypothesis   is   correct,  and   that 
probability  is  raised  to  a  higher  degree  by  every  new  and  success- 
ful appeal  to  reality.     On  the  other  hand,  a  valid  appeal,  experi- 
mental  or  other,  if  unfavourable,   immediately  and   conclusively 
demonstrates  the  falsity  of  the  hypothesis,  which  therefore  must  be 
abandoned  or  emended.     "  Thus  Kepler  records  that  he  advanced 
nineteen  hypotheses  which   he   afterwards    disproved,    before   he 
arrived  at  the  true  statement  of  the  laws  of  planetary  motion."  l 
"  A   similar   spirit   was    shown    by    Newton    in    respect    to    his 
hypothesis  that  the  moon  is  retained  in  her  orbit  by  the  force  of 
gravity.     From  this  hypothesis  he  calculated  that  the  moon  ought 
to  be  deflected  from  the  tangent  of  its  orbit  something  more  than 
fifteen  feet  every  minute.     But  the  apparent  deflection  was  only 
thirteen  feet.    This  discrepancy,  comparatively  small  though  it  was, 
Newton  accepted  as  a  disproof  of  his  hypothesis,  and  '  laid  aside  at 
that  time  any  further  thoughts  of  this  matter.'     But  some  fifteen 
years  later  the  distance  of  the  moon  from  the  earth  had  been  more 
exactly  ascertained,  and  Newton  repeated  his  calculations,  working 
with  these  new  values.     The  agreement  between   the   calculated 
and  the  normal  deflection  was  then  seen  to  be  remarkably  precise, 
and  the  hypothesis  became  an  established  theory."  2 

73.  Unless  an  experiment  is  entirely  aimless,  entirely  a  product 
of  unscientific  thought,  it  is  always  an  outcome  of  deduction. 
Even  when  it  is  used,  not  to  test  thinking,  but  merely  to  elicit 
fresh  information,  it  is  still  an  outcome  of  deduction ;  for  it  is  de- 
duction which  leads  us  to  suppose  that  our  experiment  will  have 
useful  results.  It  follows  that  there  are  two  ways  in  which  we 
may  use  experiment  (or  any  other  laboratory  method).  First  we 
may  use  it  as  a  deductive  test  of  previous  thinking,  in  which  it 
tends  to  secure  great  accuracy  in  thinking.  Second,  we  may  use 
it  as  a  means  to  reveal  an  obscured  fact,  when,  of  course,  it  tends 
to  secure  accuracy  in  observing.  But,  in  the  latter  case,  if  we  base 
1  Welton,  Manual  of  Logic,  vol.  ii.  p.  66.  2  Op.  cit.,  vol.  ii.  p.  88. 


44  THE  METHOD  OF  SCIENCE 

thinking  on  the  result  of  the  experiment,  in  other  words,  if  we 
reason,  not  towards  the  experiment,  but  from  it,  then  our  thinking 
is  not  tested  by  it.  We  get  information  which  may  be  very 
accurate  and  very  valuable ;  but  we  get  no  more  than  this  informa- 
tion. The  subsequent  thinking,  if  any,  may,  or  may  not,  be 
accurate.  To  discover  its  accuracy  we  have  to  use  tests  which  that 
particular  experiment  does  not  furnish.  Now  it  is  a  very  common 
delusion  that,  because  experiment  when  used  as  a  test  tends  to  render 
thinking  accurate,  therefore  all  thinking  connected  with  experiment 
tends  to  be  accurate.  Consequently  a  neglect  to  test  thinking 
founded  on  experiment,  combined  with  an  assumption  that  such 
thinking  is  necessarily  accurate,  is  very  frequent.  A  hypothesis, 
whether  resulting  from  induction  or  deduction,  which  has  stood  a 
valid  experimental  test,  has  stood  a  single  test  so  nearly  conclu- 
sive that  it  can  be  made  more  conclusive  only  by  continued  testing 
by  other  appeals  to  reality.  But  a  hypothesis  which  is  merely 
founded  on  obscured  facts  revealed  by  experiment  has  no  special 
claims  to  accuracy.  For  example,  if  I,  having  a  notion  that  Brown 
wishes  to  enter  my  house  surreptitiously,  give  him  the  opportunity 
and  entrap  him,  my  hypothesis  is  tested  by  experiment.  It  is  then 
very  nearly  conclusively  proved  ;  the  only  doubt  remaining  being 
due  to  the  fact  that  at  the  time  that  I  supposed  Brown  wished  to 
enter  my  house  he  might  not  yet  have  thought  of  it.  But  if,  on 
the  fact  revealed  by  the  experiment,  I  build  the  notion  that  he 
came  to  steal  the  spoons,  I  must  test  my  new  hypothesis  by  a  fresh 
appeal  to  reality.  It  matters  not,  however,  whether  I  discover  the 
spoons  on  him  by  a  formal  experiment  (i.e.  by  searching  him),  or 
whether  I  simply  observe  them  sticking  out  of  his  pocket.  In 
either  case  the  appeal  to  reality,  if  successful,  is  equally  decisive. 
In  everyday  life  it  is  often  not  worth  while  to  test  our  hypotheses, 
but,  however  much  science  occupies  our  thoughts,  our  thinking  is 
never  scientific  unless  we  do  so. 

74.  The  two  functions  of  experiment,  testing  and  discovery,  are 
sharply  distinct.  Nevertheless  they  are  often  confused  by  people 
who  claim  for  hypotheses  jfo&TZdfo/  on  experiment  the  high  scientific 
status  of  theories  tested  by  experiment.  We  shall  see  that  while  many 
important  biological  hypotheses  have  been  founded  on  experiment, 
there  is  hardly  an  example  of  one  which  has  been  tested  byit,or  which 
it  is  practicable  to  test  by  it.  Moreover,  we  must  ever  keep  in  mind 
the  manifest  truth  that  the  field  of  biological  experiment  is  limited. 
A  suitable  experiment,  whether  to  test  thinking  or  reveal  facts, 
cannot  always  be  devised.  Thus,  in  the  case  we  have  just  considered 


THE  DISCOVERY  AND  TESTING  45 

as  to  whether  unhealthy  conditions  are  causes  of  racial  degenera- 
tion or  of  evolution,  no  suitable  or  practicable  experiment  can  be 
1  thought  of.1  Hundreds  or  thousands  of  experiments  have  been 
i performed,  it  is  true,  but  with  the  most  inconclusive  results.2  Here, 
I  before  we  are  able  to  reach  a  valid  conclusion,  we  must  appeal  to 
la  far  wider  area  of  reality,  which  includes  not  only  the  experimental 
data,  but  very  much  more  besides.3 

75.  In  biology,  then,  the  essence  of  the  experimental  method 
does  not  consist  "  in  requiring  every  suggestion  (or  hypothesis)  to  be 
put  to  the  test  of  experiment  before  it  is  admitted  to  the  scientific 
status  " — an  impossible  task  in  many  cases  and  foolish  in  more  ; 
but  only  in  requiring  that  every  suggestion  which  can  usefully  be 
so  tested  shall  be  so  tested.  Since  such  suggestions  are  relatively 
very  few,  exclusive  reliance  on  experiment  would  result  in  a 
classification  of  facts  so  imperfect  as  to  be  unworthy  of  the  name 
of  science.  The  statement,  "  No  doubt  nature  has  carried  out 
prodigious  experiments  ;  but  we  can  never  be  certain  that  we  know 
how  she  has  obtained  her  results  until  we  can  repeat  the  process 
for  ourselves,"  4  implies  a  lack  of  insight  or  a  singular  unawareness 
of  known  facts.  For  example,  every  instance  of  an  individual 
who  has  offspring  during  or  after  suffering  from  a  general  disease 
is  a  very  stringent  experiment  carried  out  by  nature  and  not  to  be 
bettered  by  man.  The  accumulated  result  of  millions  or  billions  of 
such  experiments,  continued  for  thousands  of  years  on  hundreds  of 
successive  generations,  are — because  the  instances  are  so  numerous, 
obvious,  and  confirmatory  of  one  another,  because  we  are  able 
successfully  to  employ  every  known  method  of  induction,  and 
because  we  can  test  the  thinking  thoroughly  by  deduction — every 
whit  as  easy  to  infer  with  certainity  as  if  they  had  been  undertaken 
by  the  most  careful  experimental  worker.5  "  Controversy  "  6  implies 
criticism.  To  abandon  it  would  be  to  abandon  the  critical  method, 
which,  in  turn,  would  mean  the  rash  and  unquestioning  acceptance 
or  ignoring  of  hypotheses.  Biological  disputes  are  comparatively 
seldom  due  to  disagreements  about  facts.  Almost  always  the 
opponents  of  a  hypothesis  suppose  that  its  authors  have  drawn 
wrong  inferences,  and  their  objections  are  attempts  to  test  the 
latter  by  demonstrating  that  they  are  not  in  harmony  with  the 
conceived  system  of  reality.  Fortunately,  however,  the  labours 
of  experimental  workers  have  tended,  on  the  whole,  to  increase, 
rather  than  diminish,  controversy.  The  experimental  method  is 

1  See  §  135.  2  See  §§  132-4,  140-4,  160.          3  See  §§  145  et  seq. 

4  See  §  53  (footnote).        5  See  chapter  xiii.  6  See  §  53  (footnote). 


46  THE  METHOD  OF  SCIENCE 

not  new  in  biology.  That  which,  amid  such  a  wealth  of  patent 
facts,  is  very  new,  is  exclusive  reliance  on  obscured  facts  and  a 
confusing  of  experimental  discovery  with  experimental  testing. 
"  What  would  the  physicist  or  chemist  say  if  he  were  told  "  that 
he  must  not  use  patent  facts,  for  example  those  of  astronomy, 
when  inventing  or  testing  his  theories  ?  An  experiment,  or  any 
other  laboratory  inquiry,  is  a  mode  of  observing,  not  of  thinking. 
It  is  sometimes  an  appeal  to  reality  which  results  from  deductive 
thinking,  but  unless  correctly  thought  out,  not  necessarily  a  de- 
cisive appeal.  It  is  valuable  as  testing  our  thinking  or  as  making 
patent  a  fact  previously  obscured  ;  but  often  we  are  able  to  appeal 
to  evidence  patent  from  the  first,  and  an  obscured  fact,  newly 
discovered,  is  not  necessarily  more  valuable  to  us  than  a  patent 
fact  that  has  long  been  ignored  or  insufficiently  used.  An  observer 
is  quite  as  likely  to  found  illegitimate  thinking  on  the  results  of 
experiment  as  on  any  other  data.  Indeed,  thinking  founded  on 
experiment  has  often  been  deplorably  reckless  and  inaccurate. 

76.  The  function  of  deduction  is  not  limited  to  the  testing  of 
inductions.  "  If  the  hypothesis  is  true,  it  will  generally  be  possible 
to  infer  deductively  from  it  facts  which  have  not  been  before  ex- 
plained or  which  have  even  been  unobserved.  ...  As  Whewell 
says,  '  When  the  hypothesis  of  itself,  and  without  adjustment  for 
the  purpose,  gives  us  the  rule  and  reason  of  a  class  of  facts  not 
contemplated  in  its  construction,  we  have  a  criterion  of  its  reality, 
which  has  never  yet  been  produced  in  favour  of  falsehood.' l  The 
history  of  science  is  full  of  such  extension  and  prediction.  Thus, 
for  example,  the  discovery  of  Neptune  was  predicted  by  deductive 
reasoning  from  the  principle  of  gravitation."  2  Again,  the  universe 
is  a  unity  in  which  every  phenomenon  is  related,  however  remotely, 
to  every  other.  A  brief  yet  comprehensive  statement,  in  which 
the  relations  of  a  number  of  phenomena  are  summarized,  is  termed 
by  us  a  law ;  and  it  is  the  aim  of  science  not  only  to  express  the  re- 
lations of  phenomena  in  laws,  but  to  indicate  the  relations  of  these 
laws — to  weld  them  into  larger  syntheses,  more  comprehensive 
interpretations.3  In  this  process  of  welding  deduction  plays  an 

1  Novum  Organum  Renovatum,  p.  90. 

2  Welton,  Manual  of  Logic,  vol.  ii.  p.  100. 

3  What  is   a  natural   '  law  '  ?    It  is  commonly  described   as  an   "  observed 
uniformity,"  "the  statement  of  a  general  truth  ;    that  is,  a  truth  that  holds  good 
universally  in  that  science,  as  contrasted  with  a  particular  truth,  which  holds 
good  in  some  cases  only"   (Welton,  op.  cit.,  vol.  i.  p.   n).     But  this  definition 
is  too  wide  (see  §  586,  footnote).     The  flowers  of  the  common  primrose  are  yellow ; 
mammals  have  heads  ;    birds  are  bi-pedal.     These  are  observed  uniformities, 


LAWS  OF  NATURE  47 

essential  part.  Moreover,  here  again  it  is  a  means  of  testing  ;  for 
we  cannot  combine  incompatible,  that  is  true  and  false,  deductions. 
At  any  rate,  the  attempt  to  combine  them  tends  to  sift  the  true 
from  the  false.  First  we  gather  facts,  as  it  were,  into  bundles  by 

each  of  which  includes  a  considerable  range  of  phenomena  ;  but  they  are  scarcely 
what  we  understand  by  '  laws  of  nature.'  A  law  is  rather  a  description  of  a 
uniformity  in  the  way  in  which  bodies  affect  one  another  ;  or,  in  other  words, 
a  description  of  the  way  in  which  they  behave  under  uniform  conditions. 
Material  bodies  have  properties  or  qualities  which  bring  them  into  relation  with 
each  other.  From  uniform  relations,  consequent  on  the  possession  of  qualities 
of  like  nature,  uniform  results  follow.  Thus,  the  statement  that  all  material 
bodies  attract  each  other  directly  as  their  mass  and  inversely  as  the  square  of 
their  distance  is  unmistakably  a  law.  A  law  is,  in  fact,  a  theory ;  it  describes 
a  uniformity  in  terms  of  causation  (see  §  586)  ;  therefore  it  describes  a  uniformity 
in  the  sequence  of  phenomena.  It  is  a  peculiarity  of  a  natural  law  in  the  strict 
scientific  sense  that  we  are  able  to  deduce  consequences  from  it,  and  so  are  able 
not  only  to  link  up  with  it,  and  thereby '  explain '  phenomena  not  directly  mentioned 
in  it,  but  we  are  able  also  in  this  way  to  test  the  truth  of  it.  At  any  rate,  a  law 
is  valuable  to  us  as  a  means  of  systematizing  our  facts  in  proportion  as  we  are  able 
to  make  deductive  inferences  of  consequences  from  it.  No  consequences  worth 
mentioning  can  be  deduced  from  the  uniformities  that  common  primroses  are 
yellow,  mammals  have  heads,  and  birds  are  bi-pedal.  Here  we  do  not  describe 
ways  in  which  bodies  affect  one  another.  But  any  number  of  consequences  can 
be  deduced  from  the  law  of  gravitation.  Here  we  do  describe  a  way  in  which 
bodies  are  affected  by  each  other.  We  do  not  know  why  material  bodies  attract 
each  other,  nor  why  they  attract  each  other  in  the  degrees  that  they  do.  But, 
if  the  law  of  gravitation  is  a  correct  statement,  if  material  bodies  do  attract  each 
other  in  the  degrees  stated  in  it,  then,  since  contradictories  cannot  both  be  true, 
given  certain  conditions,  certain  consequences  must  follow.  Thus,  given  a  planet 
moving  in  accordance  with  the  laws  of  motion  with  a  certain  momentum,  at  a 
certain  distance  from  the  sun,  then  it  must  circle  in  a  certain  path  round  the  sun  ; 
given  the  moon  at  a  certain  distance  from  the  earth,  then  the  tides  of  the  ocean 
must  follow  its  course  ;  given  lack  of  support,  then  stones  must  fall  to  the  ground  ; 
given  a  fluid  condition,  then  the  surface  of  a  body  (e.g.  water)  must  conform  to 
the  general  contour  of  the  surface  of  the  earth  at  the  latitude  in  which  it  is  situated  ; 
and  so  on.  "  Those  ideas  that  hold  good  throughout  the  widest  domains  of 
research  and  that  supplement  the  greatest  amount  of  experience  are  the  most 
scientific  "  (Mach,  Principles  of  Mechanics,  p.  490).  Those  sciences  (e.g.  physics 
and  mathematics)  which  are  the  most  completely  welded  together  by  laws  and 
deductions  from  them,  are  the  most  completely  scientific,  the  most  completely 
interpretative,  the  most  completely  intelligible.  The  fewer  the  laws  necessary  for 
this  process  of  welding  the  better  ;  for  then  the  welding  is  the  more  perfect  since 
all  the  more  is  included  within  the  range  of  each  law.  Those  sciences  (e.g.  anatomy) 
that  are  the  least  deductive,  that  are  the  least  interpretative,  are  the  least  com- 
pletely scientific  (see  §  819  et  seq.).  If  the  reader  devotes  a  moment's  consideration 
to  the  subject,  he  will  perceive  that  nearly  all  thinking  about  heredity  and  evolu- 
tion,|like  much  of  the  thinking  in  mathematics  and  physics,  but  unlike  all  thinking 
in  the  '  systematic  '  sciences  (e.g.  zoology  and  botany),  consists  in  attempts  to 
explain  the  facts,  or,  in  other  words,  to  link  them  together  in  chains  of  causation. 
When  we  link  facts  in  this  way,  we  join  them  by  inferences.  An  inference  is  a 
hypothesis.  Hypotheses  can  be  proved  only  by  deductive  appeals  to  reality. 
A  law  is  a  hypothesis  that  has  been  fully  established  by  such  appeals.  All  the 


48  THE  METHOD  OF  SCIENCE 

inductions  ;  next  we  ascertain  by  deduction  whether  the  separate 
inductions  are  in  harmony  with  each  other  and  with  reality  in 
general ;  and,  lastly,  treating  each  induction  as  a  fact,  we  bind 
them  together  in  a  wider  induction  "  To  the  Deductive  Method, 
thus  characterized  in  its  three  constituent  parts,  Induction,  Ratio- 
cination, and  Verification,  the  human  mind  is  indebted  for  its 
most  conspicuous  triumphs  in  the  investigation  of  nature."  l  "  At 
any  step  of  Induction  .  .  .  the  inductive  proposition  is  a  Theory 
with  regard  to  the  Facts  it  includes,  while  it  is  to  be  looked  upon 
as  a  Fact  with  respect  to  the  higher  generalizations  in  which  it  is 
included.  In  any  other  sense  .  .  .  the  opposition  of  Fact  and 
Theory  is  untenable,  and  leads  to  endless  perplexity  and  debate. 
Is  it  a  Fact  or  a  Theory  that  the  planet  Mars  revolves  in  an  ellipse 
about  the  Sun  ?  To  Kepler,  employed  in  endeavouring  to  combine 
the  separate  observations  by  the  conception  of  an  Ellipse,  it  is  a 
Theory ;  to  Newton,  engaged  in  inferring  the  law  of  force  from  a 
knowledge  of  the  elliptical  motion,  it  is  a  Fact.  There  are  .  .  . 
no  special  attributes  of  Theory  and  Fact  which  distinguish  them 
from  one  another.  Facts  are  phenomena  apprehended  by  the 
aid  of  conceptions  and  mental  acts  as  Theories  also  are.  We 
commonly  call  our  observations  Facts,  when  we  apply,  without 
effort  or  consciousness,  conceptions  perfectly  familiar  to  us,  while 
we  speak  of  Theories  when  we  have  previously  contemplated  the 
Facts  and  the  connecting  Conceptions  separately,  and  have  made 
the  conception  by  a  conscious  mental  act."  2 

established  inferences  of  mathematics  and  physics  have  been  proved  thus.  It  follows 
that  the  aim  of  the  student  of  heredity  and  evolution  is  to  discover  laws  and  so  con- 
vert biology  into  a  deductive  science.  If  he  proceeds  according  to  the  method  by 
which  alone  interpretative  science  has  been  created  hitherto,  he  will  begin  by  col- 
lecting  and  verifying  relevant  facts ;  on  these  facts  he  will  found  inferences  ;  and 
these  hypotheses  he  will  endeavour  to  test  in  every  direction  possible  by  the  only 
means  possible — by  deductive  appeals  to  reality.  This  last  step  will  not  only 
establish  his  hypotheses  if  true,  or  disprove  them  if  untrue,  but  it  will  also  bring 
within  their  range  numbers  of  facts  which  would  not  otherwise  have  been  thought 
of  in  connection  with  them.  The  history  of  such  biological  work  as  has  involved 
thinking  about  the  sequences  of  phenomena — about  cause  and  effect — indicates 
very  clearly  that  almost  every  controversy  has  arisen  because  the  ordinary  rules 
of  logical  and  scientific  method  were  neglected.  Facts  have  been  incorrectly 
described,  or  they  have  not  been  verified,  or  hypotheses  incapable  of  proof  have 
been  formulated,  or  hypotheses  capable  of  proof  have  not  been  tested,  or  opponents 
have  ignored  the  proofs.  Owing  largely  to  the  care  with  which  facts  are  verified 
and  hypotheses  tested,  and  the  readiness  with  which  proofs  are  accepted,  contro- 
versies are  relatively  rare  amongst  the  students  of  physics,  and  rarer  still  amongst 
mathematicians.  (See  Mill,  Logic,  Bk.  III.,  from  which  a  passage  is  quoted  as  foot- 
note to  §  352.  See  also  chapters  xviii.  and  xxv.  of  the  present  work.) 

1  See  Mill,  Logic,  III.  ii.  3.     2  Whewell,  Novum  Organum  Renovatum,  p.  116. 


EXPERIMENT  IN  THE  SCIENCES  49 

77.  In    biology,    especially  in   medicine,  this  process  of  com- 
bining   inductions    is    occasionally    stigmatized    as    '  deduction.' 
Apparently  it  is  held  that  any  inference  which  unites  two  or  more 
inductions  in  a  larger  synthesis  ought  to  be  reached,  no  matter  if 
impossible,  by  a  single  untested  inference  from  particular  pheno- 
mena.    This  curious  opposition  between  fact  and  theory  is  well 
illustrated  by  the  common  declaration  that  this  or  that  inference, 
of  the  truth  of  which  the   writer  is   convinced,  "is  a  fact,  not  a 
theory  " ;  by  which  is  meant  only  that  in  the  opinion  of  the  writer 
the  inference  is  incontrovertible,  or,  in  other  words,  that  it  is   a 
theory,  not  a  hypothesis. 

78.  When,  as  in  mechanics  and  physics  generally,  nearly  all 
our  accurate  knowledge  has  been  gathered  in  the  laboratory,  it  is 
often  possible  to  test  a  new  induction  by  a  deductive  appeal  to 
other  laboratory  results  which  have  already  been  achieved  or  are 
possible  of  achievement.     It  is  largely  by  such  appeals  that  the 
facts,  inductions,  and  deductions  of  physics  have  been  welded  into 
a  science.1     Moreover,  since  most  of  the  facts  are  obscured,  the 
field  of  laboratory  discovery  is  limitless,  and,  therefore,  one  experi- 
mental  achievement   constantly  suggests  another,  with  the  result 
that  new  facts  are  continually  discovered  and  new  inductions  and 
deductions  formulated. 

79.  It  is  different  in  most  branches  of  biology,     So  much  is 
already  known,  or  can  be  ascertained  by  simple  observation,  that 
the   opportunities   of   the   laboratory  are   greatly   restricted.       If 
we   depend    solely  on  it,  if  we  close   our   eyes   to   the   universe 
outside  its  walls,  we  may,  indeed,  reach  many  valuable  facts  and 
inductions.     But   there  will   always  be  the  danger  that  we  have 
wasted   our   time — that  the   facts  have  already  been  reached,  or 
could   be  reached  more   quickly,  easily,  and  certainly  by  simple 

1  It  must  be  borne  in  mind,  however,  that  physicists  have,  especially  in 
astronomy,  made  a  very  considerable  deductive  appeal  to  the  material  supplied 
by  simple  observation.  "  The  use  of  a  scientific  instrument  does  not  make  an 
observation  into  an  experiment,  unless  the  instrument  modifies  the  object  which 
is  being  observed.  Thus  we  invariably  speak  of  observing  with  a  telescope  or  a 
microscope"  (Welton,  Manual  of  Logic,  p.  116).  "The  attraction  of  the  sun 
accounted  for  the  motions  of  the  planets  ;  the  attraction  of  the  planets  was  the 
cause  of  the  motions  of  the  satellites.  But  this  being  assumed,  the  perturbations 
and  the  motions  of  the  nodes  and  aphelia  only  made  it  requisite  to  extend  the 
attraction  of  the  sun  to  the  satellites  and  that  of  the  planets  to  each  other  ; — 
the  tides,  the  spheroidal  form  of  the  earth,  the  precession,  still  required  nothing 
more  than  that  the  moon  and  sun  should  attract  the  parts  of  the  earth,  and  that 
these  should  attract  each  other — so  that  all  the  suppositions  resolved  themselves 
into  the  single  one,  of  the  universal  gravitation  of  all  matter."  (Whewell, 
Novum  Organum  Renovatum,  p.  92.) 

4 


50  THE  METHOD  OF  SCIENCE 

observation.1  In  any  case,  since  the  inductions  reached  through 
the  laboratory  are  so  few  and  widely  separated  ;  since,  in  effect, 
there  is  no  system  of  reality  to  which  appeal  can  be  made,  or  at 
most  only  a  very  fragmentary  system,  every  induction  must  remain 
isolated  and  untested.  Under  such  conditions,  the  only  kind  of 
deduction  possible  is  one  which  expands  the  induction  without 
testing  it  or  linking  it  up  with  any  other,  which  cannot  be  tested 
itself,  and  which,  therefore,  is  valueless  and  illegitimate.2  We 
shall  see  that,  almost  without  exception,  every  important  biological 
induction  based  on  laboratory  work — important  in  the  sense  of  having 
attracted  wide  attention — has  been  expanded  in  this  way,  and  that  it 
is  the  deduction,  not  the  induction^  on  which  stress  is  laid  and  which  is 
regarded  as  the  Theory.  Moreover,  not  only  have  untested  induc- 
tions often  been  expanded  by  untested  deductions,  but,  as  often, 
the  latter  have  been  regarded  as  proved  simply  and  solely  because 
the  phenomena  on  which  they  are  remotely  based  were,  like 
those  of  physics  and  chemistry,  observed  in  the  laboratory.3 
It  is  true  that  we  are  exhorted  to  use  experiment  as  a  test, 
but,  especially  when  the  larger  problems  of  heredity  are  under 
consideration,  the  advice  is  rarely  heeded  even  by  those  who 
utter  it.  In  effect,  biologists  have  used  the  laboratory  only  as  a 
means  of  discovery. 

80.  The  theories  (laws)  of  physicists  and  chemists  have  usually 
stood  the  test  of  time,  not  because  their  facts  were  experimentally 
observed,  nor  even  because  their  data  were  capable  of  being 
exactly  measured,  but  chiefly  because,  though  the  facts  were 
difficult  to  gather,  the  thinking  founded  on  them  was  in  many 
cases  relatively  simple,  and,  more  especially,  because  it  was  in  all 
cases  very  rigorously  tested.  The  formulation  of  a  physical  or 
chemical  law  often  consists  in  little  more  than  a  bare  summary  ot 
the  facts  discovered  in  an  experiment  or  series  of  experiments,  a 
summary  almost  as  easy  to  make  as  a  classification  of  the  facts  of 
anatomy.  In  other  words  the  relations  of  the  facts  are  comparatively 
easy  to  discern.  Compare,  for  example,  Boyle's  law  of  the 

1  See  §§  225  et  seq. 

z "  The  deductions  which  Bacon  abolished  were  from  premises  hastily 
snatched  up  or  arbitrarily  assumed.  The  principles  were  neither  established  by 
legitimate  canons  of  experimental  inquiry,  nor  the  results  tested  by  that  indis- 
pensable element  of  a  rational  Deductive  Method,  verification  by  specific  experience. 
Between  the  primitive  method  of  deduction  and  that  which  I  have  attempted 
to  characterize,  there  is  all  the  difference  which  exists  between  the  Aristotelian 
physics  and  the  Newtonian  theory  of  the  heavens."  (J.  S.  Mill,  Logic,  III.  xiii.  7.) 

3  See  §§  208  et  seq.,  see  also  chapters  vii.  and  viii. 


PHYSICAL  AND  BIOLOGICAL  THEORIES  51 

behaviour  of  gases  under  pressure  with  Darwin's  theory  of  natural 
selection.  In  the  former  case  much  thought  was  needed  to  gather 
the  data  ;  but  they  could  be  exactly  measured,  and,  once  obtained, 
a  single  induction  sufficed  to  enable  the  discoverer  to  perceive 
his  law  ;  and,  though  a  great  deal  of  testing  was  still  necessary,  yet 
the  means  of  performing  it  were  not  hard  to  think  of.  In  the 
latter  case,  the  facts  lay  patent  but  multitudinous  under  the  eyes 
of  every  man.  Individuals,  as  regards  some  of  their  characters  at 
any  rate,  could  be  measured  with  exactness ;  but  the  measurements 
of  no  child  agreed  with  those  of  its  parents.  The  difficulty  lay, 
therefore,  not  so  much  in  observing  facts  as  in  interpreting  them — 
in  tracing  hidden  analogies,  in  seeing  likenesses  amid  differences, 
in  separating  the  relevant  from  the  irrelevant,  essentials  from  non- 
essentials,  in  brushing  aside  the  veil  of  familiarity,  in  discarding 
superstitions,  in  devising  tests.  Boyle's  difficulties,  however 
great,  were  not  of  the  same  order  as  Darwin's.  They  lay 
mainly  in  discovering  the  facts,  all  of  which  were  obscured. 
Darwin's  difficulties  lay  in  tracking  his  way  through  the  enormous 
and  confusing  maze  of  patent  facts  that  spread  and  grew  around 
him. 

8 1.  Obviously  biology  does  not  lend  itself  to  experiment  so 
readily  as  physics  and  chemistry.     Apart  from  the  circumstance 
that  many  of  its  facts  are  patent,  it  is   too  complex.     The  first 
interpretation    of  a   physical    or   chemical    experiment    is   often 
accepted  without  cavil,  and  is  comparatively  rarely  overthrown. 
But  seldom  is  the  first  interpretation  of  a  biological  experiment 
accepted   without   hot  controversy,  and  it  is  quite  usual  for  the 
original  interpretation  to  be  overthrown  and  replaced  by  another, 
and   another,   and    yet    another.      These  difficulties  of  interpre- 
tation   indicate     the    difficulties     of    satisfying    the    conditions 
which   make    experiment  useful — the  difficulty  of  so  eliminating 
irrelevant   complications,    that   in   the   case   of  each   experiment 
only   one   interpretation   of    the   result    is   possible,    or   at   least 
reasonable. 

82.  The  notion  that  deduction  is  necessarily  illegitimate  and 
dangerous  is  demonstrably  incorrect.    That  opinion  has  never  guided 
successful  students  in  their  efforts  to  interpret  nature.    It  is  illegiti- 
mate only  when  we  start  with  an  unproved  assumption,  or  when  it  is 
used  merely  to  expand  untested  inductions  by  thinking  which  cannot 
itself  be   tested  by  an  appeal  to  reality.     Rightly  used,  it  is  our 
prime  means  of  securing  accuracy  when  thinking  about  sequences  of 
events.     Physicists  have  constantly  used  it,  and  with  magnificent 


52  THE  METHOD  OF  SCIENCE 

results.1  Mathematics,  the  most  exact  of  all  sciences,  is  almost 
purely  deductive.  Many  of  the  more  important  biological 
generalizations  could  not  have  been  confirmed  or  even  reached 
without  the  employment  of  deduction.2  Deduction  is  as  essential 
a  part  of  human  mental  operations  as  induction.  We  seldom 
use  the  word  *  therefore '  except  when  our  thinking  is  deductive. 
All  calculation  is  deduction.  Our  every-day  thinking — that 
incessant  play  of  thought,  that  associating,  disassociating, 
comparing,  discriminating,  inferring,  in  which  we  are  incessantly 
engaged — is  largely,  indeed  mainly,  deductive.  We  gather  facts 
from  the  world  around  us  and  by  processes  of  induction  reach 
thousands  or  tens  of  thousands  of  conclusions.  But,  like  the  parts 
of  a  scattered  machine,  the  universe  our  mind  constructs  for  us 
would  have  no  meaning,  no  unity,  and  our  knowledge  little 
utility,  unless  these  inductions  were  linked  together,  and  amplified, 
and  multiplied  a  thousand-fold  by  deduction.  It  is  hardly  possible, 
even  for  a  young  child,  to  become  aware  of  a  sight,  sound,  odour, 
taste,  or  tactile  sensation  without,  consciously  or  unconsciously, 
recalling  facts  and  generalizations  previously  formulated,  and 
linking  the  new  experience  to  them  by  deductive  thinking.  Nature 
drives  us  ceaselessly  to  the  acquirement  of  skill  in  deduction, 
without  which  we  would  be  lost  in  a  chaos.  Our  intelligence  is  due 
to  it.  The  scientific  imagination  is  usually  but  another  name  for 
its  daring  yet  restrained  and  careful  employment.  Not  a  single 
monument  of  the  power  of  human  thought,  embodied  in  the 
literature  of  the  past,  but  is  full  of  it.  No  great  man  of  action  or 
thought,  from  statesman  and  general  to  traveller  and  scientific 
worker,  has  existed  but  was  a  master  of  it.  Not  even  the  simplest 
tool  was  ever  thought  of,  made,  or  used  but  through  the  employ- 
ment of  it ;  indeed  the  whole  history  of  invention  and  the  application 
of  invention  is  but  a  chapter  in  the  history  of  deductive  thought. 
Only  by  means  of  it,  by  appealing  from  our  inductions  back  again 
to  the  facts,  can  we,  especially  when  some  complex  matter  is  under 
consideration,  take  the  whole  of  the  evidence  into  account.  As 
a  mode  of  thinking  it  is  an  adaptation,  the  highest  product  of 

1  "  Newton's  comprehension  of  logical  method  was  perfect ;    no  hypothesis 
was  entertained  unless  it  was  definite  in  conditions,  and  admitted  of  unquestion- 
able deductive  reasoning,  and  the  value  of  each  hypothesis  was  entirely  decided 
by  the  comparison  of  its  consequences  with  facts."     (Jevons,  Principles  of  Science , 

P-  583.) 

2  For  example  the  theories  of  evolution  and  natural  selection,  both  of  which, 

moreover,  were  founded  on  facts  that  had  been  collected  mainly  by  simple 
observation.     See  §§350-1. 


DEDUCTION  53 

mental  evolution,  to  the  use  of  which  we  are  continually  driven  by 
the  most  imperious  of  our  instincts.1  Lacking  it  we  should  be 
imbeciles  of  that  not  very  uncommon  kind  that  has  a  considerable 
memory  for  facts  but  cannot  learn  to  link  them  together  except  in 
a  very  rudimentary  way.  The  only  people  by  whom  it  is  not 
habitually  used  are  actual  idiots  and  imbeciles  of  a  low  type.  I 
use  the  words  advisedly  and  literally  in  reference  to  phenomena 
which  may  easily  be  observed — in  reference  to  idiots  and  imbeciles 
who  are  medically  certified  and  placed  under  restraint  as  such.2 
One  of  the  main  causes  of  the  mental  inferiority  of  the  lower 
animals  is  that,  like  imbeciles,  they  are  unable  to  employ  it. 
Scientific  deduction,  like  scientific  induction,  differs  from  our 
common  use  of  the  process  only  in  the  greater  precautions  we 
take  to  make  it  accurate.  It  would  be  strange  if  a  process,  so 
useful  and  necessary  in  the  ordinary  affairs  of  life,  should  become 
valueless  and  dangerous  the  moment  we  endeavoured  to  use  it  with 
care,  and  if  men,  to  become  scientific,  must  cease  to  be  rational. 

83.  All  the  foregoing  is,  I  take  it,  quite  indisputably  true.  At 
any  rate,  all  that  I  have  said  about  the  right  method  of  scientific 
inquiry  is  indisputably  true.  No  one  will  maintain  that  facts 
gathered  in  one  way  are  on  that  account  more  valuable  than 
equally  authenticated  facts  gathered  in  another  way,  or  that  it  is  a 
rational  proceeding  to  found  untested  judgments  on  fragmentary 
evidence  when  completer  evidence,  by  which  the  judgments  may 
be  tested,  is  available — to  use,  for  example,  only  data  gathered  by 
one  laboratory  method  (e.g.  experiment)  when  relevant  data 
gathered  by  another  laboratory  method  (e.g.  biometry)  or  by 
simple  observation  is  at  hand.  It  may  be  said  that  no  one  has 
ever  maintained  that  authentic  and  relevant  facts  should  be 
ignored  or  that  hypotheses  should  be  left  untested.  No  one, 
indeed,  would  venture  to  do  so  openly  and  formally.  But  theory 
and  practice  are  not  identical,  and  such  astonishing  dicta  as  "  The 
day  of  vague  and  inaccurate  thinking  is  past;  we  must,  like  physicists 
and  chemists,  rely  on  experiment,"  "  The  problems  of  heredity 
can  only  be  solved  in  the  laboratory  and  breeding-pen,"  are  not  un- 
common, and  have  meant  in  practice,  as  we  shall  see  in  numerous 
instances,  nothing  other  than  an  ignoring  of  relevant  data  combined 
with  a  neglect  to  test  thinking.  Untested  hypotheses — hypotheses 
which  are  merely  founded  on  laboratory  work,  but  are  taken  as 
proved  by  it — are,  in  fact,  exceedingly  common  in  biology.3  At 

1  See  §  666.  2  See  §§  762  et  seq. 

3  See,  for  example,  chapters  iv.  to  x. 


54  THE  METHOD  OF  SCIENCE 

present,  however,  I  desire  merely,  but  as  strongly  as  possible,  to 
fix  the  reader's  attention  on  the  theory  of  scientific  inquiry  and 
obtain  his  assent  to  it.  He  must  bear  in  mind  that  the  method 
of  work  on  which  I  insist  is  no  new  thing.  It  is  the  method 
which  has  been  proclaimed  as  the  only  right  one  by  every 
authority  who  has  both  thought  about  and  expressed  himself  on 
the  subject ;  it  is  the  one  which  has  been  followed  by  every  great 
scientific  worker ;  it  is  the  one  by  which  the  truth  of  every  law  of 
nature  known  to  us  has  been  established.  At  the  risk  of  tiresome 
reiteration,  this  method  of  work  may  be  indicated  as  follows  : — 
When,  as  in  the  study  of  heredity  and  evolution,  we  wish  to 
establish  the  relations  between  facts  that  occur  in  sequences  (i.e. 
when  we  wish  to  discover  chains  of  cause  and  effect),  we  must 
formulate  hypotheses.  But  hypotheses  remain  mere  guesses  until 
they  have  been  tested  and  found  to  be  true.  They  can  be  tested 
only  by  making  deductive  inferences  of  consequences  from  them 
and  then  appealing  to  reality  to  ascertain  if  these  consequences 
actually  follow.  If  a  hypothesis  enables  us  to  predict  correctly  in 
this  way,  it  is  in  all  probability  true  ;  and  it  is  the  more  certainly 
true  (and  useful)  in  proportion  to  the  number  of  different  correct 
predictions  it  enables  us  to  make — in  proportion  as  it  accords 
with  the  whole  universe  of  relevant  truth.  Moreover,  such  deduc- 
tive appeals  to  reality  not  only  enable  us  to  test  hypotheses  and 
so  convert  them  into  laws,  they  not  only  enable  us  to  bring  within 
the  range  of  each  real  law  masses  of  data  which  had  not  been 
used  for  the  corresponding  hypothesis,  but  they  enable  us  to 
perceive  the  relations  between  the  several  laws,  and  so,  by  linking 
the  laws  together,  to  advance  towards  that  harmony  of  knowledge 
which  is  one  of  the  principal  aims  of  science. 

84.  To  return  to  the  problem  of  recapitulation — the  facts  are 
that  the  offspring  of  each  successive  generation  resemble  their 
parents  closely  but  not  exactly,  and  that,  apart  from  the  differen- 
tial play  of  stimuli,  this  imcomplete  resemblance  is  due  to  a 
recapitulation  with  variations  of  the  parental  development.  The 
induction  is  that  the  development  of  the  individual  is  a  recapitula- 
tion, with  additions  and  omissions,  of  the  evolution  of  the  race.1 

1  The  thinking  here  is  somewhat  complex,  and  complex  thinking  is  often 
denounced  as  '  deductive,'  especially  by  medical  writers.  But  when  we  bear  in 
mind  that  individual  progression  depends  on  a  complete  recapitulation  (as  regards 
the  parts  under  consideration)  of  the  parental  development  plus  an  additional 
step,  and  retrogression  on  an  incomplete  recapitulation,  and  that  racial  pro- 
gressions and  retrogressions  are  nothing  other  than  the  sums  of  progressions  and 
retrogressions  made  by  individuals  during  the  evolution  of  the  race,  the  thinking 


CAUSATION  AND  SIMPLE  ENUMERATION  55 

The  deduced  consequences  are  that  developing  individuals 
probably  present  traces  of  ancestral  forms.  The  appeal  to  reality 
is  the  search  for  such  traces.  A  successful  appeal  ends  in  the 
discovery  of  them  and  the  proof  of  the  induction.  It  is  agreed  on 
all  hands  that  they  do  actually  occur. 

85.  Hitherto,  biologists  have  always  founded  the  notion  that 
development  is  a  recapitulation  of  evolution  on  the  evidence 
supplied  by  embryos.  Adopting  the  method  of  '  induction  from 
simple  enumeration,'  they  have  concluded  that  the  developing 
young  of  living  beings  often  resemble  organisms  lower  in  the 
scale  of  life  than  the  adult  type,  and  thence  have  deduced  the 
further  conclusion  that  the  resemblance  is  due  to  a  descent  from 
lower  forms.  That  which,  rightly  used,  should  have  furnished 
tests,  has  been  made  the  material  on  which  was  built  the  hypothesis 
which  has  remained,  therefore,  a  much  controverted  working 
hypothesis.  I  have  endeavoured  to  establish  it  as  a  theory,  an 
invariable  law,  founded  on  facts  of  causation  and  tested  by  an 
appeal  to  reality.  "  It  cannot  be  too  often  repeated,  that  we  ought 
never  to  depend  on  frequency  of  occurrance,  wherever  it  is 
possible  to  have  recourse  to  facts  of  causation."  x  "  The  notion  of 
cause  "  is  "  the  root  of  the  whole  theory  of  Induction."  2  The  facts, 
all  of  which  are  patent,  and  the  reasoning,  some  of  which  is 
deductive,  are  before  the  reader.  If  now,  bearing  in  mind  the 
undisputed  truth  that  offspring  recapitulate  (with  variations) 
parental  development,  he  is  able  to  conceive  individual  develop- 
ment, as  anything  other  than  a  recapitulation,  however  altered,  of 
the  life-history  of  the  race,  he  is  capable  of  an  intellectual  feat 
which  is  quite  certainly  beyond  my  powers. 

is  seen  to  be  obviously  inductive.  To  reach  the  notion  that  development  is  a 
recapitulation  of  evolution  we  merely  sum  up  the  persistent  variations  of  the 
successive  generations. 

1  Fowler,  Inductive  Logic,  pp.  270-1. 

2  J.  S.  Mill,  Logic,  III.  v.  2.     If  the  reader  disagrees  with  the  notion  that  we 
create  better  science  when  we  link  together  our  material  by  facts  of  causation 
than  when  we  simply  enumerate  likenesses  and  differences,  it  would  be  well  if 
he  now  broke  the  continuity  of  this  work  and,  before  proceeding  further,  read 
chapters  xviii.  and  xxv.     Meanwhile,  I  should  be  glad  if  he  took  this  problem 
of  recapitulation  as  a  test  case  and  asked  himself  which   is   the  better  science, 
the  disputable  and  often  disputed  guess  that  is  founded  on  a  simple  enumeration 
of  the  likenesses  between  embryos  and  lower  forms  of  life,  or  the  indisputable 
truth  that  is  demonstrated  when,  starting  with  the  familiar  generalisation  that 
offspring  recapitulate  the  parental  development,  we  establish  a  chain  of  causation, 
and  so  reach  the  necessary  conclusion  that  the  development  of  the  individual  is 
a  brief  and  inaccurate  r<?sum<?  of  the  evolution  of  the  race  ? 


CHAPTER  IV 
THE  LAMARCKIAN  DOCTRINE 

Adaptation — The  main  problem  of  heredity — Theories  of  evolution — The 
Lamarckian  hypothesis — The  Darwinian  hypothesis — The  incompatibility  of 
the  two — Evidence  against  the  former — The  most  decisive  proof  of  all — Cor- 
relation— Diseases — Maternal  impressions — Telegony. 


T 


86.  f  |  ^O  the  student  of  heredity  and  evolution,  who  not  only 
gathers  facts  but  strives  to  interpret  them  by  ascertain- 
ing their  causal  relations  one  to  another,  the  cardinal 
fact  of  life  may  be  said  to  be  the  close  adaptation  of  every  species 
to  its  environment,  and  the  equally  close  co-adaptation  of  the 
organs,  tissues,  cells,  and  functions  of  the  normal  individual  to  one 
another.  Thus  the  normal  man,  the  normal  ant,  and  the  normal 
oak  are  closely  fitted  during  all  stages  of  development  to  the  con- 
ditions of  their  surroundings,  and  could  exist  in  no  other.  Within 
plant  and  animal  bodies,  with  rare  and  uncertain  exceptions,  every 
structure  and  function,  no  matter  how  vast  their  multitude  and  com- 
plexity nor  how  great  the  changes  undergone  during  development, 
works  in  exquisite  co-adaptation  with  all  its  neighbours.  Hardly  one 
of  all  these  structures,  whether  useful  in  preserving  the  individual 
life,  or  sexually  ornamental  and  therefore  useful  in  preserving  the 
species,  whether  functionally  active  or  vestigial,  but  serves,  or  has 
served,  or  will  serve  during  the  life  of  the  individual  the  great 
purpose  of  adaptation,  the  great  purpose  of  enabling  the  individual 
to  survive  and  transmit  his  germ-plasm  to  offspring.  Nearly  one 
and  all,  their  existence  has  or  had  no  significance  other  than 
utility  to  the  individual  or  to  the  race.  So  surely  as  we  learn 
much  about  a  structure,  almost  so  surely  do  we  discover  its  function, 
its  utility  in  the  past  or  the  present  of  the  race,  or  the  past  or 
the  present  or  the  future  of  the  individual.  It  is  impossible  to  use 
language  too  emphatic  on  the  necessity  to  the  student  of  heredity 
and  evolution  of  bearing  constantly  in  mind  this  all-important 
truth  of  adaptation.  Its  wonderful  completeness  has  been  denied, 
but  only,  I  think,  when  people,  even  scientific  men,  have  founded 
their  thinking  on  exceptions  instead  of  the  rule,  and  even  then 

66 


ADAPTATION  57 

only  when  they  have  assumed  that  structures  have  no  utility  if 
they  have  been  unable  to  detect  the  utility.  Such  exceptions  are 
extremely  rare  in  very  well-known  and  understood  types,  and 
correspondingly  more  frequent  in  plants  and  animals  less  familiar 
to  us.  We  may  find  them  in  plants,  insects,  and  molluscs,  but  we 
have  only  to  devote  a  moment's  thought  to  the  closely  co- 
ordinated structures  and  functions  of  such  a  being  as  man  to 
perceive  how  very  exceptional  is  the  exception  to  the  rule  of 
utility.1 

87.  Adaptation  must  be  the  anchor  about  which  the  student's 
thoughts  for  ever  swing,  the  touchstone  by  which  he  must  test 
every   theory   of  racial    change   and    individual   variation.      The 
normal  individual  is  a  bundle  of  adaptations.     His  growth,  his 
development,  is  nothing  other  than  a  process  of  individual  adapta- 
tion.     Evolution    is    nothing    other    than    a   process    of    racial 
adaptation.     A  theory  of  evolution  is,  or  should  be,  nothing  more 
than  an  attempt  to  explain,  or,  if  we  prefer,  summarize  in  brief 
terms  the  processes  by  which  adaptation  is  achieved.     A  theory  of 
heredity  seeks  to  account  for  likenesses  and  differences  between 
parents  and  offspring ;  if  it  fails  to  be  compatible  with  a  theory  of 
evolution  which  correctly  interprets  the  facts  in  terms  of  adapta- 
tion, it  is  sure  to  be  erroneous.     Many  theories  of  heredity  and 
evolution   have   gone,   or   are   going   to  the   limbo   of  discarded 
hypotheses,  merely  because  they  do  not  accord  with  the  truth  that 
species  are  closely  adapted  by  all  or  nearly  all  their  structures  and 
functions  to  the  environment.     The  plain  fact  that  living  beings 
are  able  to  exist  is  proof  of  adaptation.     Many  students  of  heredity 
and  evolution,  especially   those   belonging   to   the   experimental 
school,  will    think   that  I  put  the  case  too  strongly,  but  I  shall 
justify  every  statement  up  to  the  hilt. 

88.  To  be  adapted  to  the  environment  in  which  he  is  produced, 
the  child  must  resemble  the  parent     The  resemblance  is  due  to 
his  recapitulation  of  the  parental  development.     Presumably  the 
recapitulation  occurs  because  the  germ-plasm  in  the  fertilized  ovum 
whence  the  child  sprang   resembled  (because  derived  from)  the 
germ-plasm  of  the  fertilized  ovum  whence  the  parent  sprang — 
because  the  two  portions  of  germ-plasm  had  similar   hereditary 
tendencies  which  were  awakened  by  stimuli  similar  in  kind  and 
degree.     Thus  half  the  task  of  the  student  of  heredity  is  easily 
accomplished.       He   is   able — in  a  way,  superficial  perhaps,  but 
valid  as  far  as  we  know — to  account  for  the  resemblances.     Of 

1  See  §§  648-9. 


58  THE  LAMARCKIAN  DOCTRINE 

course,  if  we  choose,  we  may  seek  to  pry  deeper  and  speculate 
about  the  composition,  the  '  architecture,'  of  the  germ-plasm,  and 
the  hidden  springs  of  its  behaviour.  But,  in  the  almost  total  lack 
of  verifiable  evidence,  we  should  be  reduced  to  mere  valueless 
guessing — valueless  because  incapable  of  being  tested.  We  know, 
however,  that  there  must  be  a  germ-plasm,  a  substance  that  is  the 
bearer  of  heredity,  in  the  germ-cell,  and  that  in  the  case  of  every 
species  of  living  beings  it  must  possess  definite  hereditary 
tendencies  which  differ  from  those  of  every  other  species,  and  we 
have  very  strong  reasons  for  supposing  that  it  is  derived  by  direct 
and  real  descent  from  the  germ-plasm  of  preceding  germ-cells. 
On  these  tolerably  sure  foundations  we  are  able  to  build  a  very 
great  deal. 

89.  It  is  more  difficult  to  account  for  the  differences  in  detail 
between  parent  and  child  than  for  the  resemblances  in  mass. 
Some  of  these  differences  are  readily  explained  by  the  fact  that 
the  stimuli  under  which  parent  and  child  develop  are  never  exactly 
similar.  The  nutriment,  use,  and  injury  which  awakened  the 
hereditary  tendencies  of  the  parent  are  sure  to  have  differed  some- 
what from  those  which  awakened  the  tendencies  of  the  child. 
These  account  for  the  acquired  differences.  The  real  difficulty 
arises  when  we  seek  to  account  for  '  variations/  for  those  innate 
differences  which  are  founded,  not  on  differences  in  stimuli,  but  in 
germ-plasms.  We  have  to  answer  the  question,  "  How  does  it 
happen  that  the  child  '  varies '  from  the  parent  ? "  Or  more 
precisely,  "  How  does  it  happen  that  the  germ-plasm  of  the  child 
differs  from  that  of  the  parent  ?  "  If  the  problem  is  extremely 
complex  and  difficult,  it  is  also  very  important.  Indeed  it  is 
perhaps  the  main  problem  of  heredity.  If  we  solve  it  correctly, 
we  shall  have  discovered  not  only  the  correct  interpretation  of 
many  of  the  phenomena  of  heredity,  but,  since  all  racial  change  is 
founded  on  the  variations  of  individuals,  of  evolution  also.  In  this 
matter,  just  because  the  problem  is  so  complex  and  difficult,  we 
must,  linking  together  a  number  of  principles  reached  by  induction, 
consider  heredity  and  evolution  together.  Variations,  taken  by 
themselves,  are  capable  of  a  number  of  interpretations,  any  one  ot 
which,  as  far  as  we  know,  may,  or  may  not,  be  correct ;  taken  in 
conjunction  with  the  facts  of  adaptation  it  becomes  evident  that 
only  one  interpretation  can  possibly  be  true. 

90.  Before  beginning  our  investigations  we  must  make  up  our 
minds  to  do  some  very  careful  thinking.  I  do  not  say  this  because 
we  are  about  to  deal  with  exceptionally  abstruse  matters,  nor 


THE  ORIGIN  OF  VARIATIONS  59 

because  I  think  the  reader's  task  will  be  especially  difficult,  but 
because  we  are  now  coming  on  very  debatable  ground  where 
hardly  two  scientific  men  think  alike,  and  because  this  question  of 
the  causation  of  variations  lies  at  the  very  heart  of  our  subject. 
Unless  we  have  clear  ideas  concerning  it,  we  shall  have  misty  ideas 
concerning  cognate  subjects.  Accordingly,  as  we  form  one  or 
other  opinion,  we  shall  take  one  or  other  of  several  widely 
divergent  views  of  heredity,  of  evolution,  of  all  the  problems  of 
life.  We  shall  have  to  deal  with  large  and  complex  bodies  of 
evidence,  a  thing  which  cannot  be  done  without  using  correspond- 
ingly complex  processes  of  thought,  though  unfortunately  attempts 
to  shirk  the  necessity  have  been  common  enough.  I  think  we 
have  materials  that  are  amply  sufficient  to  enable  us  to  come  to  a 
definite  conclusion.  I  believe  also  that  the  problem  is  still 
regarded  as  debatable  only  because  men,  instead  of  considering 
the  whole  mass  of  evidence  and  so  testing  their  thinking,  have 
often  founded  their  opinions  on  isolated  bodies  of  facts.  Often, 
displaying  a  superstitious  and  pedantic  reverence  for  facts  collected 
by  this  or  that  method  of  inquiry,  they  have  ignored  massive  and 
indisputable  evidence,  collected  in  other  ways.  A  simplicity  of 
view  has  often  been  achieved  in  this  manner,  but  at  the  expense 
of  breadth  and  depth  of  view,  and,  therefore,  of  correctness,  clear- 
ness, and  comprehensiveness  of  perception.  In  other  words,  the 
phenomena  have  not  been  viewed  in  their  complete  setting. 

91.  Species  arose  and  were  adapted  to  their  environments 
either  by  miracle  or  by  natural  processes.  If  by  miracle,  then 
three  methods  of  creation  are  conceivable,  (i)  All  species,  extinct 
or  persisting,  may  have  been  called  into  being  simultaneously,  or 
nearly  so,  in  full  possession  of  the  characters  which  they  have  ever 
since  possessed.  If  this,  the  popular  hypothesis,  be  true,  there  can 
have  been  no  evolution,  or  very  little,  and,  therefore,  since  untold 
numbers  of  species  still  persist,  the  environments  can  have  under- 
gone no  important  alterations.  The  entirely  conclusive  evidence 
furnished  by  geology  proves,  however,  that  both  species  and 
environments  have  undergone  vast  though  gradual  changes.  (2) 
Unchanging  species  and  varieties  may  have  been  created,  not 
simultaneously,  but  successively  during  a  period  which  extended 
over  many  millions  of  years,  and  in  a  way  that  exactly  mimicked 
evolution,  and  apparently  was  designed  to  delude  us  into  a  belief 
in  it.  Probably  hardly  anyone,  whether  acquainted  or  not  with 
the  facts,  now  accepts  this  solution,  which  logically  should  impel 
us  to  believe  that  our  domesticated  breeds  of  plants  and  animals 


60  THE  LAMARCKIAN  DOCTRINE 

are  special  creations.  (3)  There  may  have  been  evolution,  but 
evolution  miraculously  directed.  This  belief  implies  that  species 
changed  in  adaptation  to  a  changing  environment,  not  because  the 
environment,  acting  on  them,  caused  the  change,  but  because  a 
Power,  in  a  sense  outside  the  environment,  moulded  them  into 
adaptation  to  it  without  using  it  as  an  instrument.  It  is,  however, 
a  rule,  as  good  in  science  as  in  the  ordinary  affairs  of  life,  not  to 
appeal  to  the  supernaturnal  until  natural  explanations  have  been 
exhausted. 

92.  A  variety  of  the  belief  in  miracle  has  sometimes  been 
advocated  by  men  of  science — chiefly  botanists.  God  and  miracle 
are  not  mentioned,  but  we  are  told  that  species  are  fitted  to  their 
environments  by  means  of  an  inherent  adaptive  growth-force  ;  that 
is,  we  are  asked  to  believe  that  offspring — not  merely  surviving 
offspring,  but  offspring  in  general — tend  to  vary  from  their  parents 
in  such  a  way  as  to  be  better  fitted  to  the  environment,  and  that 
thus  evolution  results.  If  we  examine  the  evidence  on  which  the 
supporters  of  this,  the  '  bathmic,'  hypothesis  rely,  we  find  no  very 
strenuous  attempt  to  distinguish  between  variations  and  modifica- 
tions— between  inherent  alterations  dependent  on  alterations  in  the 
germ-plasm,  and  changes  that  result  merely  from  a  differential  play 
of  stimuli.  Many  of  the  examples  quoted  by  them  appear  to  be 
nothing  other  than  what  Mr  A.  Bacot  has  termed  '  repertoire 
patterns.' 1  Thus  the  plant  Berberis  vulgaris  bears  leaves  in  a 
moist  and  spines  in  a  dry  atmosphere.  Hippuris  has  two  forms, 
one  terrestrial  and  the  other  aquatic,  which  may  be  converted,  the 
one  into  the  other,  by  changing  the  environment,  the  leaves  under 
the  water  growing  long  and  undulating,  those  in  the  air  short  and 
erect.  It  has  been  assumed  by  the  supporters  of  the  bathmic 
theory  that  all  these  differences  are  germinal — that  the  individual 
that  develops  in  the  one  way  in  the  one  situation,  differs  innately  to 
the  extent  of  his  differences  from  the  individual  that  develops  in 
the  other  way  in  the  other  situation.  But,  as  a  fact,  we  have  no 
reason  to  suppose  that  they  are  other  than  acquired.  They  furnish, 
however,  very  interesting  evidence  that  nature  may  fit  a  species 
for  existence  in  two  separate  environments,  in  each  of  which  it  is 
capable  of  flourishing,  but  in  one  of  which,  under  one  set  of  stimuli, 
it  develops  characters  different  from  those  which  it  develops  in  the 
other  environment  under  another  set  of  stimuli.  Presumably,  such 
species  have  evolved  under  conditions  which  rendered  this  capacity 
for  alternative  development  useful  because  the  one  environment 
1  Nature,  Jan.  3Oth,  1908,  p.  294. 


ADAPTIVE  GROWTH-FORCE  61 

was  liable  to  be  changed  into  the  other.  The  evidence  in  favour 
of  the  existence  of  an  adaptive  growth-force,  then,  is  very  equivocal. 
On  the  other  hand,  if  it  be  true,  as  massive  evidence  demonstrates, 
that  organs  and  structures  undergo  progressive  evolution  (i.e. 
become  larger  and  more  complex)  only  when  they  are  endowed 
with  a  considerable  degree  of  utility  (i.e.  selection  value),  and 
retrogression  only  when  they  lack  utility,  the  bathmic  doctrine  is 
certainly  untrue,  and  we  are  able  to  explain  changes  in  structure 
or  function,  or  increase  or  decrease  in  them  without  mysticism. 
Normal  growth,  after  all,  is  only  a  form  of  adaptation  ;  it  occurs 
only  when  it  fits  the  species  more  closely  to  the  environment ;  and 
it  is  adaptation,  not  increase  in  size  or  complexity,  that  is  the 
main  problem.  We  do  not  explain  why  a  force  is  adaptive  or 
render  it  less  mysterious  by  terming  it  an  adaptive  growth-force. 
Moreover,  the  fact  that  breeders  are  able  to  modify  plant  and 
animal  types  in  innumerable  directions  is  evidence  of  some  value 
that  variations  occur,  not  in  one  or  two  or  a  few  directions,  but  all 
round  the  specific  mean  like  bullet-marks  round  a  bull's-eye.  We 
shall  see  how  strongly  this  latter  hypothesis  is  confirmed  by  the 
facts  of  human  evolution  against  disease. 

93.  Rejecting  miracle  then,  there  remain  only  two  scientific 
hypotheses  which  are  intelligible,  at  any  rate  at  first  sight— the 
Lamarckian  doctrine  of  adaptation  through  the  transmitted  effects 
of  use,  disuse,  and  injury,  and  the  Darwinian  doctrine  of  natural 
selection.  Doubtless,  in  a  way,  the  Lamarckian  doctrine,  curiously 
combined  with  a  belief  in  special  creations,  has  been  a  part  of 
popular  superstition  since  prehistoric  times.  Even  now  "  the  man 
in  the  street "  is  firmly  convinced  that  parental  '  acquirements  '  are 
readily  transmuted  into  '  inborn '  traits  in  the  child.  But  Lamarck 
first  of  all,  or  at  least  most  consistently,  gave  scientific  form  to  the 
popular  belief  by  allying  it  to  a  theory  of  evolution.  His  specula- 
tions attracted  little  attention,  even  amongst  students,  till  Darwin 
and  Wallace  formulated  their  theory  of  Natural  Selection.  Subse- 
quently, for  a  score  or  more  of  years,  scientific  thinkers,  including 
Darwin  himself,  believed  that  the  organic  world  arose  partly  through 
the  '  transmission '  of  acquirements  and  partly  through  the  natural 
selection  of  favourable  variations.  During  the  last  twenty  years, 
however,  scientific  opinion  has  veered  to  a  conviction  that  Darwin 
and  Wallace,  the  most  modest  of  men,  worked  better  than  they 
supposed — or  rather  than  Darwin  supposed,  for  Wallace  has  long 
and  consistently  repudiated  the  Lamarckian  doctrine.  It  is  now 
generally  believed  that  acquirements  are  never  *  transmitted/  and, 


62  THE  LAMARCKIAN  DOCTRINE 

there/ore,  that  evolution  proceeds  entirely  on  lines  of  natural 
selection.  This  emended  doctrine  has  received  the  name  of 
'  Neo  -  Darwinian.'  Often,  however,  it  is  termed  simply  the 
'  Darwinian,'  though,  as  we  see,  Darwin  did  not  hold  it  in  its 
entirety. 

94.  The  question  as  to  whether  acquirements  are,  or  are  not, 
transmitted  has  been  the  subject  of  probably  the  most  lengthened 
and    ardently    debated   of  biological    controversies.       Prolonged 
investigation,  in  the  course  of  which  the  plant  and  animal  kingdoms 
were  ransacked,  failed  to  reveal  a  single  convincing  and  unmistak- 
able instance  of  the  transmission  of  an  acquirement.     But  though 
the  Lamarckian  doctrine  is  abandoned  by  the  majority  of  serious 
students,  it  is  worth  while  to  devote  some  space  to  it,  partly  because 
it  is  still  an  article  of  popular  belief,  partly  because  the  study  of 
it  will  enable  us  to  contrast  it  with  the  Darwinian  theory  and 
so  achieve  a  better  understanding  of  what  is  meant  by  Natural 
Selection,  and  partly  because  we  shall  thus  early  have  an  oppor- 
tunity to  demonstrate  the  importance  of  testing  every  speculation 
by  a  rigorous  deductive  appeal  to  reality. 

95.  The  Lamarckian  doctrine  supposes  that  parental  'acquire- 
ments '  tend  to  be  *  inherited,'  in  however  small  a  degree,  by  off- 
spring.    That  is,  it  supposes  that  useful  characters,  which  evolution 
enables  the  parent  to  acquire  as  a  response  to  use  or  injury,  tend  in 
the  child  to  be  transmuted  into  less  adaptive  characters,  which  develop 
in  response  to  the  stimulus  of  nutriment.     In  the  face  of  common 
experience  its  scientific  adherents  did  not  maintain  that  the  whole 
of  the  parental  acquirement  was  commonly  '  inherited.'     Thus,  if 
the  tails  of  a  pair  of  dogs  were  amputated,  it  was  not   thought 
probable  that  the  offspring  would  be  born  tailless,  though  it  was 
believed  that  this  sometimes  happened.     It  was  thought  merely 
that  some  portion  of  the  parent's  loss  tended  to  be  *  inherited,'  and 
therefore,  that  if  the  mutilation  were  repeated  during  successive 
generations,  a  race  with  diminished  tails  and  ultimately  a  tailless 
race  would  result.     Again,  it  was  not  believed  probable  that,  if  a 
man  increased  the  size  of  his  muscles  by  exercise,  all  of  the  increase 
would  be  '  inherited,'  but  only  some  of  it.     In  fact,  it  was  main- 
tained that  acquirements  were  transmitted,  as  a  rule,  only  ' faintly ' 
and  '  fitfully.' l 

96.  Obviously  the    Lamarckian  hypothesis  professes  to  be  a 
theory  both  of  heredity  and  evolution,  the  latter  being  an  induction 
from  the  former.     As  a  theory  of  heredity  it  seeks  to  account  for 

1  See  Romanes,  Darwin  and  after  Darwin,  vol.  ii.  p.  152. 


THE  TRANSMISSION  OF  ACQUIREMENTS  63 

variations  by  supposing,  in  effect,  that  each  parental  acquirement 
tends  to  alter  the  germ-plasm  in  such  a  particular  and  remarkable 
manner  that  the  'acquirement'  is  reproduced  by  the  child,  in 
whole  or  part,  as  an  *  inborn  '  trait.  As  a  theory  of  racial  change, 
it  supposes  that  progression  is  due  mainly  to  use  and  to 
such  injuries  and  nutritive  changes  as  result  in  increase  of 
size  (or  function),  whereas  retrogression  is  due  principally  to 
disuse  and  to  such  injuries  or  nutritive  changes  as  result  in 
decrease  of  size  or  function,  for  example  from  mutilations  or 
starvation. 

97.  Now,  whether  acquirements  be,  or  be  not,  transmitted,  we 
know  that  children  often  vary  from  their  parents  (differ  innately  at 
birth  from  what  their  parents  were  at  birth)  quite  apart  from  such 
'  transmission.'     Thus   the  child  of  normal  parents  may  be  born 
with  an  extra  digit,  a  character  which  is  never  acquired  (i.e.  de- 
veloped) by  the  parent  in  response  to  the  stimulus  of  injury  or  use. 
The  problem  which  we  have  to  solve,  then,  is  not  whether  the 
Lamarckian  theory  of  heredity  correctly  accounts  for  the  occurrence 
of  all  variations,  but  only  whether  it  correctly  accounts  for  the  occur- 
rence of  any  variations.     Similarly  many  characters  are  present  in 
every  species  the  evolution  of  which  cannot  conceivably  have  been 
due  to  the  '  transmitted '  effects  of  use,  injury,  or  any  other  stimuli, 
for  example  nearly  all  the  characters  of  plants,  and  in  animals, 
such  characters  as  brilliant  colour  markings,  the  external  ears,  the 
reproductive  organs,  and  feathers  and  hairs.     It  follows,  therefore, 
that  while  the  Lamarckian  doctrine  may  afford  a  partial  explana- 
tion of  the  occurrence  of  variations  and  of  evolution,  it  cannot 
afford  a  complete  explanation. 

98.  The  unicellular  organism  "  is  a  part  and  usually  a  half  of 
the  parent."     Its   structures,  therefore,  are  derived  from   similar 
structures  in  the  parent;  that  is,  there  is  real  inheritance.     The 
multicellular  organism,  on  the  other  hand,  is  derived  from  a  single 
cell,  which,  after  dwelling  as  a  parasite  in  the  parent  cell-community, 
leaves  its  home  to  become  the  ancestor  of  a  new  community.     The 
parts  of  this  new  cell-community,  therefore,  are  not  derived  from 
similar  parts  of  the  parent ;  that  is,  there  is  no  real  inheritance  of 
the  characters  of  the  first  community  by  the  second.     The  two 
resemble  one  another  for  a  totally  different  reason — because  their 
development   has    been    directed    by    similar    germ-plasms,   the 
hereditary  tendencies  of  which   have  been  awakened   by  similar 
stimuli.     It  is  evident,  therefore,  that  the  problem  of  the  alleged 
transmission  of  acquirements  is  not  the  same  in  both  cases.     Indeed, 


64  THE  LAMARCKIAN  DOCTRINE 

the  question  of  the  transmission  of  acquirements  as  presented  by 
multicellular  organisms  has  no  parallel,  and  can  have  none  amongst 
unicellular  types.  This  distinction  is  clear  to  most  students  of 
heredity,  who,  as  a  rule,  maintain  that  parental  acquirements  may 
be  inherited  by  unicellular,  but  not  by  multicellular  plants  and 
animals.  Occasionally,  however,  some  writers,  chiefly  medical  men, 
attempt  to  argue  from  the  one  question  to  the  other  ;  but  the 
reasoning  is  obviously  invalid.  On  the  other  hand,  multicellular 
organisms  present  a  problem  which,  while  totally  distinct  from  the 
question  of  the  *  transmission '  of  their  acquirements,  is  a  real 
parallel,  though  seldom  or  never  recognized  as  such,  to  the 
problem  of  the  'transmission'  of  acquirements  as  presented  by 
unicellular  types.  We  shall  consider  it  in  its  proper  place.1 
At  present  we  must  confine  ourselves  to  the  much  debated 
*  transmission,'  which  Lamarck  maintained  was  the  source  of  the 
evolution  of  the  higher  organisms. 

99.  A  cell-community,  a  multicellular  plant  or  animal,  is  com- 
pounded of  germ-cells  and  somatic  cells.  The  Lamarckian  doctrine 
supposes  that  when  the  somatic  cells  acquire  characters  under  the 
influence  of  use  or  injury,  these  acquirements  so  affect  the  germ- 
plasm  contained  in  the  germ-cells  that  the  cell-communities  which 
spring  from  them  tend  to  reproduce  the  acquirements  of  the  somatic 
cells,  not  as  '  acquirements,'  not  as  direct  effects  of  use  or  injury, 
but  as  nutritional  characters.  Thus,  when  the  muscle  cells  of  a 
man,  for  example,  increase  in  number  and  power  as  a  result  of  use, 
the  germ-cells  dwelling  within  the  cell-community  are  supposed  to 
be  affected  in  such  a  remarkable  and  particular  way  that  the 
children  which  arise  from  the  latter  tend  to  develop  larger  and 
more  efficient  muscles  without  the  aid  of  use.  Speaking  meta- 
phorically, the  acquirements  made  by  Brown  and  Jones  (the  somatic 
cells)  are  supposed  to  so  affect  Robinson  and  White  (the  germ- 
cells)  that  the  descendants  of  the  latter  are  characterized  by  traits 
which  look  like  those  which  Brown  and  Jones  '  acquired,'  but  which, 
since  they  are  '  inborn,'  are  really  very  different.  Obviously  this 
power  of  transmuting  acquirements — if  it  exists — is  a  very  wonder- 
ful thing,  which  must  have  arisen  de  novo  amongst  the  higher  types  ; 
for,  as  we  have  just  seen,  nothing  like  it  occurs,  or  can  occur, 
amongst  unicellular  forms,  which  separate  and  do  not  form  cell- 
communities,  and  so  cannot  influence  one  another  in  this  way.  A 
large  and  complex  organism,  such  as  man,  may  make  a  million 
different  acquirements,  each  of  which  is  distinct  from  every  other ; 

^ee  §  137. 


H.  SPENCER'S  HYPOTHESIS  65 

and  therefore,  if  the  Lamarckian  hypothesis  be  true,  are  differently 
recorded  in  the  germ-cells. 

100.  How    did   this    amazing    power    arise  ?      What    is    the 
machinery  for  it?     If  we  exclude  miracle,  the  only  conceivable 
causal  agent  is  Natural  Selection — at  any  rate  I  can  conceive  no 
other,  and  I  do  not  believe  the  reader  can.     But  Natural  Selection 
is  concerned  only  in  shaping   adaptations.     It   must  be  shown, 
therefore,  that  this  power  of  transmuting  acquirements  is  generally 
useful   to  species ;    for  it  is  inconceivable  that  Natural  Selection 
would  or  could  call  into  existence  so  wonderful  and  complex  a 
power  if  the  result  injured  the  race  and  stultified  itself.    Obviously 
it  must  not  be  assumed,  as  is  always  done  by  the  adherents  of 
Lamarck,  that  the  existence  of  this  power  is  '  natural '  and  inevit- 
able— so   natural   and    inevitable  that   it   is  necessary   rather   to 
disprove  than  to  prove  the  actuality  of  the  transmission. 

101.  It  is  argued  sometimes  that  the  multicellular  individual  is 
not  really  multicellular  ;    but   that  protoplasmic  bridges  connect 
the  cells  and  convert  the  whole  into  a  sort  of  gigantic  unicellular 
organism.     Presumably,   on   similar   grounds,   we   should    regard 
Siamese  twins,  not  as  two  individuals,  but  as  one.     But,  even  if  we 
agree  that  the  multicellular  is  really  unicellular,  the  difficulties  to 
be  surmounted  by  the  Lamarckian  theorist  are  not  diminished.     It 
still  remains  true  that  the  parts  of  the  child  are  not  derived  from 
similar  parts  of  the  parent,  but,  on  the  contrary,  from  a  minute 
portion  of  him  (the  germ-cell).     We  gain  nothing  by  calling  this 
portion  a  portion  instead  of  a  separate  cell ;  for  it  is  just  as  hard  to 
understand  how  this  portion  can  be  influenced  with  percision  in 
millions  of  definite  different  directions  by  changes  occurring  else- 
where.    Herbert  Spencer  sought   to  overcome  the  difficulty  by 
conceiving  the  living  body  as  a  kind  of  crystal,  the  nature  of  which 
was  liable  to  be  so  radically  changed  by  the  action  of  the  environ- 
ment that  detached  portions  of  it  tended  to  assume  the  new,  not 
the  old  shape.      A  chip  from  a  crystal,   it  is  true,  grows  in   a 
suitable  medium  into  the  likeness  of  the  parent  crystal  ;  but  there 
the   analogy   ends.       The   crystal   does   not   spontaneously   emit 
portions  of  itself  that  serve  as  starting-points  for  daughter  crystals, 
which  vary  from  the  parent.     It  is  not  heterogeneous  in  structure. 
It  is  not  a  storehouse  of  active  energy.     It  does  not  alter  pro- 
foundly and  continuously  in  shape  during  growth  as  the  embryo 
does,  nor  with  the  seasons  like  plants  or  the  stag  when  he  sheds 
his  antlers,  nor  from  moment  to  moment  like  a  man  when  he  moves. 
It  does  not  consist  of  a  fluctuating  stream  of  matter  which  enters 

5 


66  THE  LAMARCKIAN  DOCTRINE 

as  nourishment  and  is  subsequently  exchanged  for  other  matter. 
It  is  not  a  focus  of  chemical  activity.  It  grows  only  on  the  surface. 
In  short,  the  analogy  is  strained  and  false. 

1 02.  The  Darwinian  hypothesis,  at  any  rate  as  at  first  enunciated, 
was  not  a  theory  of  heredity,  but  only  one  of  evolution.     It  did 
not  seek  to  account  for  variations,  but  took  them  for  granted  and 
built   on    that  foundation.     Indeed,  the   only  theory  of  heredity 
formulated  by  Darwin,  that  of  Pangenesis,  was  designed  more  to 
satisfy  the  claims  of  the  Lamarckian  conception  of  evolution  than 
of  the   one  which   has  received  his  name.     We  shall  see,   how- 
ever, if  we  submit  the  theory  of  Natural  Selection  to  a  rigorous 
deductive  inference  of  consequences,  and    appeal   to   reality   for 
confirmation,  that  one  particular  theory  of  heredity,  and  that  one 
only,  fits  it,  whereas  all  the  others  are  incompatible  with  it. 

103.  The  theory  of  Natural   Selection  is   founded  mainly  on 
two  undisputed  inductions  and  two  deductions  from  them.     The 
inductions  are  (a)  that  offspring,  while  resembling  parents  on  the 
whole,    always   vary   from    them   somewhat    in   every   character, 
being  perhaps  superior  in  some  characters  and  inferior  in  others ; 
and  (b)  that  in  every  species  the  number  of  individuals  that  come 
into  being  exceeds,  sometimes  very  greatly,  the  number  of  those 
who  survive  and  have  offspring.     The  deductions  are  (a)  that,  as 
a  general  rule,  the  individuals  selected  by  nature  for  survival  are, 
on   the   whole,  better   adapted    to   the   environment   than    those 
selected  for  elimination ;  and  (b)  that  in  this  way  the  '  specific 
mean,'  the  racial  average,    is   raised,  and  consequently  evolution 
results.     Unlike  the  doctrine  of  the  transmission  of  acquirements, 
the  theory  of  Natural  Selection,  as  held  by  its  modern  followers, 
really  aspires  to  account  for  all  adaptations. 

104.  The   main   contrast  between   the   Lamarckian   and    the 
Darwinian    hypotheses    arises    from    the    fact    that    the    former 
attributes  progressive  evolution  to  influences  that  act  beneficially 
on  the  individual,  whereas  the  latter  attributes  it  to   influences 
that   kill   or   weaken,  and   so   on   the   average   prevent   the   un- 
fittest,  the   most  affected,  from  having  offspring,  or  at  any  rate 
their  full  quota  of  offspring.     Until  very  recently  all  students  of 
heredity  were  zoologists  or  botanists,  or  men  who  drew  their  facts 
from  materials  collected  by  them.     Even  now  it  is  difficult  to  per- 
suade such  workers  that  useful  evidence  may  be  drawn  from  other 
sources.    When,  therefore,  they  thought  of  elimination,  their  minds 
turned    naturally  to  quick   or   sudden   death,  the  only  forms  of 
elimination  familiar  to  us  in   wild   nature.     They  conceived  the 


LAMARCKIAN  AND  DARWINIAN  DOCTRINES       67 

animal  as  growing  strong  and  active  through  contending  with 
rivals,  escaping  from  enemies,  or  pursuing  prey  ;  or  else  as  perishing 
in  the  fullness  of  his  vigour.  They  imagined  the  plant  as  over- 
whelmed by  the  storm,  or  as  emerging  more  hardy  and  firmly 
rooted  from  the  struggle.  In  brief  they  conceived  the  same  agent 
as  eliminating  the  weak  and  as  strengthening  the  strong.  They 
had  no  difficulty,  therefore,  in  believing  that  a  hypothesis  which 
attributed  evolution  to  the  transmission  of  acquirements  was  com- 
patible with  one  which  attributed  it  to  the  survival  of  the  fittest- 
They  had  thought  of  no  facts  by  which  they  could  test  this 
opinion.  Consequently  for  many  years  scientific  men  were 
adherents  of  both  doctrines,  as  a  few  still  are. 

105.  But  agencies  which,  while  strengthening    the  survivors, 
destroy  the  weak  by  violent  deaths,  are  not  the  only  causes  of 
elimination.     Some  agencies,  for  example  many   human  diseases, 
both  destroy  the  weak  and  weaken  the  strong.     Apparently  they 
are  never  other  than  harmful,  at  any  rate  they  are  never  beneficial. 
Almost  every  individual  of  many  human  races  is  exposed  to  one 
or  more  agencies  of  this  sort.    If,  then,  the  Lamarckian  doctrine  is 
true,  such  agencies  should  be  causes  of  continuous  racial  deteriora- 
tion.    On  the  other  hand,  if  that  doctrine  is  false  and  the  Dar- 
winian doctrine  true,  if  the  acquirements  of  the  parent  end  with 
the  parent  and  are  not  inherited  by  the  child,  then  such  agencies 
should,  through  the  raising  of  the  racial  average  in  every  generation 
by  the  survival  of  the  fittest,  be  causes  of  protective  evolution. 
Here  the  two  theories  are  in  conflict ;   we  see  plainly  that  they 
are   incompatible ;    if   the    one   gives   a   true   account   of    racial 
change,  the  other  does  not ;  for  it  is  impossible  that  a  race  can 
both   deteriorate    and    improve    in    the   same   characters   at    the 
same  time.     Therefore  we  are  able  to   test   them  by  means   of 
crucial   instances;   that  is,  we  are  able  to  appeal  to  reality  for 
guidance.      The  fact  that  every  race  (e.g.   English   and    Negro) 
that  has  been  exposed  to  any  disease  (e.g.  tuberculosis  or  malaria) 
has   undergone   no   discoverable   deterioration,   but    has    become 
resistant  to  the  disease,  has  evolved  against  it,  precisely  in  pro- 
portion to  the  length  and  severity  of  its  past  affliction,  is  decisive 
evidence  against  the  Lamarckian  and  in  favour  of  the  Darwinian 
doctrine. 

106.  It  is  true  that  some  human  diseases  (e.g.  measles)  leave 
the  individual  who  recovers  from  them  with  an  increased  power  of 
resisting    subsequent   attacks,    and    that    generations    that   have 
suffered  from  these  maladies  are  on  that  account  proportionately 


68  THE  LAMARCKIAN  DOCTRINE 

resistant.  But  it  can  be  shown  that  the  resisting  power  which  the 
individual  develops  is  radically  different  in  kind  from  that  which 
the  race  evolves.1  The  latter  power,  therefore,  cannot  have  arisen 
through  the  inheritance  of  acquirements.  In  any  case,  the  fact 
remains  that  many  diseases  and  other  conditions  (e.g.  tuberculosis, 
slum-life,  and  alcoholism),  which  confer  increased  resisting  power 
on  the  race,  not  only  confer  none  on  the  individual,  but  actually 
tend  to  destroy  any  that  he  may  possess.2  Here  the  race  evolves 
in  a  direction  precisely  contrary  to  the  direction  taken  by  the 
acquirements  of  the  individual. 

107.  Another  point  of  contrast,  important  but  seldom  noted, 
between  the  two  hypotheses,  is  the   differing  complexity  of  the 
racial    change  which   would   necessarily  result   on  the  one  hand 
from  natural  selection,  and  on  the  other  from  the  transmission  of 
acquirements. 

108.  The  natural  inference  from  the  theory  of  Selection,  the 
theory  which  attributes  the  evolution  of  a  character,  not  to  the 
amount  of  use  to  which  it  is  subjected  but  to  its  utility  (selection 
value), is  that  progressive  evolution  proceeds  on  lines  of  comparative 
simplicity.     We  have  abundant  evidence  that  structures  that  do 
not  assist  appreciably  in  the  preservation  of  life  or  in  the  struggle 
for  offspring,  for  example  the  wings  of  a  species  of  bird  to  which 
flight  has  become  useless,  or  the  special  features  of  our  prize  breeds 
of  plants  and  animals,  tend  to  deteriorate  when  no  longer  selected. 
It  is  a  reasonable  inference,  therefore,  that  a  certain  stringency  of 
selection   is   necessary   for   progression,   that   a   lower  degree   of 
stringency  suffices  for  the  maintenance  of  a  structure,  and  that  a 
still  lower  degree  of  stringency,  or,  even  more,  complete  cessation 
of  selection,  is  followed  by  retrogression.     These  inferences  are 
borne  out  by  what  we  observe   in  nature.     For  instance,  as  we 
shall  see  later,  the  human  race  is  undergoing  progression  in  a  few 
particulars.3      The    mass   of    human    characters,    however,     are 
stationary  or  nearly  so.     They  were  evolved  during  different  but 
overlapping  periods  of  a  long-extended  past,  and  their  progression 
ceased  when  further  increase  was  not  of  utility.     No  matter  how 
much  used   or  useful,  they  are   merely   maintained  at  a  certain 
standard  of  efficiency.     Thus  apparently,  the  human  hand,  heart, 
lungs,  liver,  and  many  other  characters  have  changed  little,  if  at 
all,  during  thousands  of  years.     Lastly,  many  human  structures, 
having  quite  lost  utility,  have  become  vestigial,  presumably  through 
cessation  of  selection.     The  germ-plasm  has  so  altered  that  they 

1  See  §  432.  2  See  §  435.  3  See  chapter  xiii 


THE  INUTILITY  OF  TRANSMISSION  69 

cannot  now  develop  in  the  individual  under  any  form  of  stimulus — 
neither  under  nutriment,  nor  use,  nor  injury. 

109.  On  the  other  hand,  were  the  Lamarckian  doctrine  true, 
every  structure  which  was  much  used  (e.g.  the  lower  limbs  of  man, 
and,  in  particular,  the  joints)  would  increase  in  size  proportionately 
to  the  amount  of  use — with  results  disastrous  to  the  co-adaption 
of  structures ;  every  structure  which  was  little  used  (e.g.  organs 
of  generation),  or  was  not  '  used '  (e.g.  hair,  bones  of  skull),  or  was 
disused,  would  degenerate,  and  structures  which  were  much  exposed 
to  injury  (e.g.  wings  of  butterflies)  would  tend  to  deteriorate. 
Evolution  and  degeneration  would  thus  proceed  on  lines  as 
complex  as  the  individual  and  with  extraordinary  results.  Here, 
then,  again,  if  acquirements  were  transmissible,  since  species 
would  be  affected  as  wholes,  since  almost  every  individual  would 
alter  in  the  same  direction,  natural  selection  would  have  no  scope. 
The  species  would  drift  helplessly  out  of  harmony  with  the 
environment.  In  point  of  fact,  therefore,  the  Lamarckian 
hypotheses  of  heredity  and  evolution,  when  closely  examined  (i.e. 
when  we  make  rigorous  deductive  inferences  of  consequences), 
are  found  not  to  be  theories  of  adaptation  at  all  ;  and  they  are 
always,  not  merely  sometimes,  incompatible  with  the  Darwinian 
hypothesis. 

no.  It  is  obvious  at  a  glance,  that,  if  actual  injuries  and 
growths  (e.g.  scars),  which  arose  in  response  to  injuries,  were  trans- 
muted into  characters  which  arose  inevitably  (because  developed 
under  the  stimulus  of  nutriment),  in  the  absence  of  injury  the  result 
would  be,  not  adjustive,  but  distinctly  harmful.  Similarly,  char- 
acters which  develop  under  the  stimulus  of  use  are  particularly 
useful  when  so  developed.  They  possess  a  quality  of  usefulness 
which  is  lacking  in  those  developed  under  the  stimulus  of 
nutriment — a  kind  of  unconscious'  intelligence,  as  it  were,  which, 
within  the  limits  of  possible  development,  enables  the  individual 
to  grow  just  the  right  characters  to  just  the  right  extent.  Thus 
the  muscles  of  the  athlete,  whose  need  is  greater,  are  larger  and 
more  efficient  than  those  of  the  ordinary  man  ;  but  they  diminish 
when  he  goes  out  of  training.  The  arms  of  the  sailor  tend  to 
develop  more  in  proportion  than  his  legs,  whereas  the  reverse  is 
the  case  with  the  soldier.  The  heart  and  tkidneys  develop  beyond 
the  ordinary  in  disease  when  life  depends  on  a  response  to  an 
increased  strain  thrown  on  them.  The  skin  thickens  and  hardens 
when  and  where  such  changes  are  useful.  When  the  need  is  over, 
all  use-developments  tend  to  disappear,  and  the  organism  is 


70  THE  LAMARCKIAN  DOCTRINE 

relieved  of  unnecessary  burdens.  The  capacity  to  develop  under 
the  stimulus  of  use,  therefore,  renders  the  individual  more  adapt- 
able than  he  would  otherwise  be.  In  fact,  he  is  doubly  adapted 
to  the  environment :  first  by  the  evolution  of  his  race,  which  fits 
him  to  the  environment  common  to  all  the  members  of  his 
species,  and  second  by  peculiarities  in  his  own  development,  which 
arise  under  the  stimulus  of  use  and  injury  and  fit  him  to  his  own 
special  surroundings.1 

in.  Yet  another  quality  of  special  usefulness  is  conferred  by 
the  capacity  to  develop  under  the  strain  of  use.  The  only  organ- 
isms which  possess  this  power  to  any  considerable  extent  are  the 
more  complex  animals.  Thus,  a  man  is  compounded  of  thousands 
of  structures,  all  of  which  must  be  closely  co-adapted,  or  the 
individual  as  a  whole  lacks  efficiency.  The  greater  the  complexity, 
the  more  necessary  but  difficult  is  nature's  task  of  maintaining 
co-adaptation.  By  the  evolution  of  the  power  of  growing  under 
the  strain  of  use  the  difficulty  is  in  great  measure  surmounted,  for 
each  structure  thus  endowed  develops  in  proportion  to  the  strain 
placed  on  it.  The  size  and  strength  of  the  human  heart,  for 
example,  is,  in  general  terms,  always  in  proportion  to  the  needs  ot 
the  individual,  be  he  healthy  or  diseased,  big  or  small — especially 
in  early  life,  when  the  power  of  developing  under  the  strain  is 
greatest.  On  the  other  hand,  the  magnitude  of  such  structures  as 
the  teeth,  the  ears,  the  nose,  the  hair,  and  the  reproductive  organs, 
all  of  which  are  wholly  *  inborn/  is  often  comparatively  dispro- 
portionate as  compared  with  associated  parts.2 

112.  It    follows   that  if  a  character   which  developed    in    the 

1  See  chapter  xxi. 

2  Much  has  been  written  on  the  '  correlation '  of  parts  and  qualities.    The  word 
has  been  used  to  describe  at  least  three  distinct  classes  of  phenomena.     First,  there 
is  the  infrequently  observed  but  much  discussed  tendency  of  parts,  which  have 
apparently  no  close  functional  connection,  to  vary  together  in  a  non-adaptive 
way — in  a  way  that  has  not  resulted  directly  from  evolution,  but  is  seemingly  a 
kind  of  by-product  of  it.     Thus  "  white  cats  which  have  blue  eyes  are  almost 
always  deaf"   (Darwin,  Animals  and  Plants,  vol.  ii.  p.  322)  ;    "multiplicity  of 
horns  in   sheep  is  generally  accompanied  by  great  length  and  coarseness  of  the 
fleece"    (Youatt   on   Sheep,  pp.    142-69,  quoted   by   Darwin).     "White   terriers 
suffer  most  from  distemper,  white  chickens  from  a  parasitic  worm  in  their  trachea, 
white  pigs  from  scorching  in  the   sun,  and  white   cattle  from  flies"    (Vernon, 
Variations  in  Plants  and  Animals,  p.  85).     A  normal  individual  (e.g.  man)  is  a 
bundle  of  adaptations.     He  consists  of  a  thousand  or  ten  thousand  parts,  each 
of  which  is  co-adapted,  not  merely  to  a  single  other,  but  to  many  others,  and  must 
have  been  so  co-adapted  during  all  the  shifts  and  changes  of  evolution.     It  is 
difficult  to  understand  how  this  perpetual  co-adaptation  in  all  directions  can  have 
been  secured  unless  each  part  has  been  independently  variable.     Only  so  can 
the  species  have  been  sufficiently  ductile  to  the  action  of  Natural  Selection.     We 


THE  ^UTILITY  OF  USE- ACQUIREMENTS  71 

parent  under  the  stimulus  of  use  were  '  inherited  '  by  the  child 
(i.e.  were  developed  in  the  latter  under  the  stimulus  of  nutriment), 
a  great  part  of  its  utility  would  be  lost,  for  the  character  would 
then  develop,  not  in  proportion  to  the  needs  of  the  individual,  but, 
within  limits,  in  proportion  to  the  supply  of  nutriment.  The 
alleged  power  of  transferring  characters  due  to  injury  and  use  from 
their  own  category  to  another,  therefore,  is  clearly  not  an  adapta- 
tion. If  it  exists  at  all  it  must  have  been  evolved,  not  through 
Natural  Selection,  but  through  miracle — through  a  miracle  which 
was  designed,  not  to  benefit  but  to  injure  the  species. 

113.  Formerly,  as  noted  already,  the  magnitude  of  the  use- 
acquirements  made  by  the  higher  animals  was  not  realized  by 
biologists.  Indeed  it  is  very  seldom  realized  even  now.  The 
study  of  them  is  still  the  most  neglected  department  of  biology. 
In  fact  only  exceptional  acquirements  were  and  are  regarded  as 
acquirements.  Ordinary  acquirements,  those  made  by  every 
normal  individual  who  reaches  maturity,  were  thought  to  be  inborn 
traits.  For  instance,  the  truth  that  almost  the  whole  growth  of  the 
infant's  limbs  after  birth  is  due  to  use  was  undreamed  of.  This 
failure  to  realize  the  magnitude  and  importance  of  the  use-acquire- 
ments has  led  to  a  failure  to  note  the  evolution  of  the  '  inborn ' 
power  of  making  them.  The  use-acquirement  was  regarded,  not  as 
an  adaptation,  a  product  of  evolution,  but  as  a  kind  of  accident 
which  might  befall  any  structure,  and  which,  being  transmitted, 
might  result  in  the  evolution  of  inborn  characters.  Its  magnitude 
was  tacitly  assumed  to  be  so  small  that  the  great  part  it  plays  in 
co-adapting,  in  correlating,  the  parts  of  the  individual,  and  otherwise 
fitting  him  to  the  environment  was  not  thought  of.  On  the  other 
hand  it  was  believed  that  the  transmission  of  use-acquirements 

are  compelled  to  assume,  therefore,  in  accordance  with  the  facts  as  far  as  observed, 
that  this  non-adaptive  kind  of  correlation  is  very  rare — rare,  that  is,  as  compared 
to  the  total  number  of  the  characters  of  the  normal  individual.  Second,  there  is 
that  kind  of  correlation  which  results  directly  from  Natural  Selection,  and  which 
secures  the  proportionate  development  of  those  characters  which  develop  under 
the  stimulus  of  nutrition.  For  example,  a  large  infant  has  usually,  not  only  a  large 
body,  but,  correlated  with  it,  proportionately  large  limbs  and  head.  Third, 
there  is  that  kind  of  correlation  which  results  from  the  proportionate  development 
of  associated  structures  under  the  strain  of  use.  Since  this  kind  of,  correlation 
is  superimposed  on  and  perfects  the  correlation  of  parts  which  have  developed 
under  the  stimulus  of  nutrition,  it  is  usually  the  closest  of  all.  Thus  the  correlation 
in  size  between  the  muscles  of  the  human  adult  arm  is  obviously  closer  than  that 
between  ear  and  head.  Correlation  in  the  second  and  third  instances  is  only 
another  name  for  co-adaptation,  and  evidence  is  hardly  needed  to  establish 
the  fact  that  living  beings  tend  to  have  their  parts  so  adjusted  as  to  render  them 
capable  of  existence. 


72  THE  LAMARCKIAN  DOCTRINE 

did  much  in  the  course  of  generations  to  bring  about  co-adaptation 
and  correlation.  Thus  Herbert  Spencer  maintained  that  without 
the  transmission  of  use-acquirements  the  evolution  of  the  higher 
animals  would  have  been  impossible.  He  instanced  the  weighty 
horns  of  the  elk,  pointing  out  that  their  usefulness  to  the  individual 
depended  on  the  co-adaptation  of  a  thousand  parts  in  head,  neck, 
trunk,  and  limbs,  and  insisted  that,  since  it  is  unlikely  that  all  of 
them  can  ever  have  varied  favourably  together  in  any  individual 
and  practically  impossible  that  they  can  have  so  varied  in  a 
succession  of  individuals,  their  co-adaptation  was  explainable  only 
on  the  hypothesis  that  acquirements  tend  to  become  inborn. 
Obviously,  his  reasoning  was  founded,  first  on  a  belief  that  all 
characters  grow  under  the  stimulus  of  use,  and  second  on  an 
insufficient  appreciation  of  the  magnitude  of  use-acquirements, 
which,  as  in  other  cases,  brought  about  co-adaptation  between  the 
horns  of  the  elk  and  the  structures  associated  with  them. 

1 14.  More  recently  some  biologists,  more  particularly  Professors 
Lloyd  Morgan,  Osborn,  and  Mark  Baldwin,  while  admitting  that 
use-acquirements  are,  in  all  probability,  not  transmissible,  have 
argued  that  their  presence,  by  acting  as  a  screen  behind  which 
progression  could  occur,  may  conduce  indirectly  to  evolution  of  a 
kind  which  closely  mimics  that  which  would  result  from  the  inherit- 
ance of  them.  Thus  suppose  drowning  were  a  stringent  selective 
cause  of  human  elimination,  then  those  individuals  who  learned 
to  swim  quickest  and  best  would  survive  in  the  greatest  numbers. 
If  any  of  their  offspring  varied  in  such  a  way  that  they  were  able, 
in  some  measure,  to  swim  '  naturally '  (i.e.  without  learning),  they 
would  be  at  an  advantage,  and  would  survive  in  larger  numbers 
than  contemporaries  who  had  more  to  learn.  In  this  way  a  human 
race  that,  like  many  lower  animals,  could  swim  instinctively,  would 
ultimately  be  established.  In  other  words,  without  any  inheritance 
of  acquirements,  characters,  which  in  the  ancestors  developed 
under  the  influence  of  use,  would  in  the  descendants  develop 
under  the  influence  of  nutriment.  But  the  evidence  that  this  view, 
which  has  not  been  tested  by  an  appeal  to  reality,  though  the  test  is 
possible,  is  mistaken  is  overwhelming.  Characters  developed  under 
the  influence  of  use  are,  as  we  see,  very  much  more  adaptive  than 
those  developed  under  the  stimulus  of  nutriment.  Therefore, 
though  there  is  unlimited  evidence  of  the  former  replacing  the 
latter,  there  is  none  to  the  contrary.  Thus  the  helplessness,  the 
immaturity  of  the  human  being,  before  he  has  made  his  use- 
acquirements,  demonstrates  to  what  an  extent  the  power  of 


THE  STRONGEST  EVIDENCE  OF  ALL  73 

developing  under  the  influence  of  nutriment  has  been  displaced  in 
him  by  that  of  developing  under  the  stimulus  of  use.  For  example, 
the  ability  to  run  and  swim  instinctively  is  so  general  amongst  the 
lower  mammalia  that  there  can  be  little  doubt  that  the  ancestors 
of  man  formerly  possessed,  but  subsequently  lost,  this  power.1 

115.  Here,  indeed,  we  have  the  strongest  evidence  of  all  against 
the    Lamarckian    hypothesis.     When   we    find    it   impossible   to 
formulate  a  probable  hypothesis  as  to  how  acquirements  can  be 
transmuted  into  inborn  characters,  or  to  conceive  by  what  process, 
short   of  miracle,  the  power  of  thus  transmuting  them  can  have 
been   evolved,  it  becomes   necessary  to  ask  for  very  strong  and 
unequivocal  evidence   of  the    alleged  transmutation.     When   we 
ascertain  by  a  rigorous  deductive  inference  of  consequences  that 
the  hypothesis  is  apparently  incompatible  with  the  fact  that  life 
exists  and  is  adapted  to  its  surroundings,  our  reasons  for  rejecting 
it  are  greatly  strengthened.     The  only  doubt  that  remains  is  as  to 
whether,  in  spite  of  all  our  testing,  we  have  reasoned  correctly. 
But  when  we  find  that  the  whole  course  of  evolution  has  been  such 
that,  so  far  from  '  inborn '  characters  tending  to  replace  '  acquire- 
ments,' the  reverse  has  constantly  happened?;  when  we  find  that  the 
human  being,  for  example,  has  lost  so  much  that  was  inborn  in  his 
remote    ancestors,    that   he   has  become    incapable    of    reaching 
maturity   except   under   the  stimulus  of  use,  all   doubt  vanishes. 
The  appeal    to   reality   then    furnishes   decisive   proof.      Having 
regard    to    the   facts,    a    supposition    directly    contrary    to    the 
Lamarckian  hypothesis  (viz.,  a  supposition  that  inborn  characters 
tend  to  be  transmuted  into  acquirements)  may  perhaps  be  main- 
tained with  some  appearance  of  probability.     But  a  supposition 
that  acquirements  tend  to  be  transmuted  into  innate  characters  is 
very  obviously  in  conflict  with  what  has  occurred  in  nature.2 

1 1 6.  Though  the  Lamarckian  doctrine  is  abandoned  by  nearly 

1  See  §  673. 

2  Most  biologists,   I   think,  reject,   or  rather  believe   that  they  reject,   the 
Lamarckian  doctrine  on   grounds  furnished  by  experiment.     I  have  heard  (so 
very  odd,  occasionally,  are  the  notions  of  scientific  men  concerning  science)  all 
other  evidence  and  reasoning,  all  attempts  to  establish  a  chain  of  causation  and 
make  biology,  like  physics  and  mathematics,  a  deductive  science,  denounced  as 
'  weak.'     But  it  appears  to  me  that  the  experimental  evidence  is  strongly  in  favour 
of  the,  at  any  rate, '  faint  and  fitful '  transmission  of  acquirements,  a  transmission 
which,  if  sufficiently  general,  would  inevitably  lead  to  racial  change.     We  cannot 
disprove  a  statement  that  an  event  sometimes  happens  by  proving  that  some- 
times it  does  not  happen.     One  positive  example  outweighs  a  hundred  negative 
instances,  and  Brown  Sequard,  Romanes,  and  numbers  of  other  observers  have 
recorded,   or   thought   they  recorded,   many.     To   this   day  French  observers, 
especially  French  medical  men,  frequently  announce  such  experiments  as  the 


74  THE  LAMARCKIAN  DOCTRINE 

all  students  of  heredity  and  evolution,  a  belief  in  it  still  lingers 
among  a  section  of  medical  men — mainly  because  the  distinction 
between  *  innate '  and  '  acquired '  characters  is  not  drawn  by 
them  with  sufficient  clearness.1  Gout,  haemophilia,  syphilis, 
mutilations,  maternal  impressions,  and  telegony  are  cases  in  point. 
Gout  is  an  acquirement,  an  injury  which  often  results  from  dietetic 
errors.  It  occurs  most  commonly  amongst  people  who  have 
exceptional  opportunities  to  eat  and  drink  to  excess.  Some 
people  are  innately  more  liable  to  contract  it  than  others — just  as 
they  may  be  innately  taller,  or  darker,  or  different  in  any  other 
way.  Their  germ-plasm  is  such  that  they  develop  the  disease 
more  readily  under  the  fit  stimuli.  There  is  even  such  a  thing  as 
"  poor  man's  gout."  Their  children  tend,  of  course,  to  reproduce 
the  parental  peculiarity  when  placed,  as  they  usually  are,  under 
similar  conditions.  All  this,  however,  affords  no  support  to 
the  contention  that  parental  excess,  or  parental  gout  resulting 
from  excess,  increases  the  liability  of  offspring  to  the  disease. 
The  well-to-do  offspring  of  poor  Irish  peasants  have  been  found 

excision  of  the  stomachs  of  dogs,  and  declare  that  the  stomachs  of  the  offspring 
are,  on  the  average,  smaller  than  the  normal.  Really,  I  suppose  most  biologists 
think  these  observers  mistaken,  because,  consciously  or  unconsciously,  they  have 
become  convinced,  actually  on  deductive  grounds,  that  it  is  impossible  and  in- 
credible that  acquirements  can  be  transmitted.  Some  distinguished  supporters 
of  the  Lamarckian  hypothesis  still  exist,  however  (see,  for  example,  Mr  Francis 
Darwin's  Presidential  Address  to  the  British  Association,  1908;  Professor  G. 
Henslow's  book,  The  Heredity  of  Acquired  Characters  in  Plants,  and  Professor 
Marcus  Hartog's  and  Dr  Mercier's  articles  in  the  Contemporary  Review,  September, 
November,  and  December  1908).  They  argue  very  rightly  from  the  experimental 
evidence,  insist  even  more  rightly  that  the  fact  that  we  are  unable  to  conceive 
how  acquirements  can  be  transmitted  is  not  proof  that  they  are  not  transmitted, 
and  declare  finally  that  they  must  be  transmitted  because  (according  to  them)  it  is 
impossible  to  conceive  how  plants  and  animals  have  evolved  into  adaptation 
to  their  surroundings  without  such  transmission.  I  have  tried  in  vain,  however, 
(see,  for  example,  the  Contemporary  Review,  October  1908)  to  persuade  them  to 
realize  that  it  is  not  the  transmission  of  acquirements,  but  the  transmutation  of 
useful  into  less  useful  or  actually  injurious  characters  that  is  really  the  subject 
of  discussion,  or  to  persuade  them  to  consider  the  truth  that,  while  nature  furnishes 
no  clear  evidence  that  inborn  traits  have  replaced  acquirements,  she  furnishes 
evidence,  perfectly  clear  and  immensely  massive,  that  the  contrary  has  happened 
on  an  enormous  scale. 

1  "  In  much  of  the  evidence  on  causation  terms  were  used  without  fixed  meaning, 
in  different  senses  by  different  witnesses,  or  in  more  than  one  sense  by  a  single 
witness.  This  confusion  has  been  no  less  noticeable  in  the  medical  than  in  the 
general  evidence  given  on  the  important  question  of  '  Heredity,'  both  before  the 
Commission  and  at  other  inquiries  of  a  cognate  kind  ;  and  it  seems  to  us  to  be 
desirable  that  this  subject,  which  forms  an  important  part  of  physiology,  should 
be  more  specially  emphasized  than  it  now  is  in  the  medical  curriculum."  (Report 
of  the  Royal  Commission  on  the  Care  and  Control  of  the  Feeble-Minded,  1908,  p.  180.) 


THE  MEDICAL  EVIDENCE  75 

to    be,  on   the   average,  as   liable   to   gout  as  the  scions  of  the 
aristocracy. 

117.  In  haemophilia  the  blood  lacks  coagulating  power  ;  there- 
fore the  flow  from  a  wound  in  a  *  bleeder/  as  a  sufferer  from  the 
disease    is    colloquially    termed,    is    difficult    to    staunch.       The 
condition  is   always  an   innate,  a  nutritional   character,  and,  as 
such,  is  reproduced  by  offspring.     Often,  however,  it  is  spoken  of 
as  '  acquired '  by  the  parent,  and  inherited  by  the  child. 

1 1 8.  On  the  other  hand,  syphilis  is  due  to  a  microbe  that 
multiplies  in  the  body,  and  may  pass  from  the  parent  to  the  germ- 
cell,   embryo,   or   foetus,  precisely   as   it   may   pass   to   an    adult 
individual.     It  is  no  more  inherited  than  a  bullet  which  pierces 
a  mother  and  enters  her  foetus.     The  microbe  elaborates  a  poison, 
a  'toxin,'  which  likewise  passes  into  the  child  with  the  nutrient 
fluids,  and  so  may  injure  it.     This  injury  also  is  never  inherited  ; 
it  is  always  an  acquirement.1 

119.  Medical  men  see  innumerable  mutilations.     Sometimes — 
very  rarely  indeed — a  child  is  born  with  a  deformity  which  bears 
some  resemblance  to  the   parental   mutilation.      Thereupon   the 
inheritance  of  the  latter  is  alleged,  the  possibility  of  coincidence 
being  ignored.      The   evidence  is  of  the   same   nature   and   not 
intrinsically  superior  to  that  which  causes  some  people  to  believe 
in  prophetic  dreams. 

1 20.  Deformities,   mutilations,  and  the  like  are   so   common 
as  to  be  observed  frequently  by  every  one.     If  a  pregnant  woman 
observes  one,  and  bears  a  normal  child,  no  notice  is  taken  of  the 
fact ;    but  if  the  child  is  deformed  she  is  apt  to   attribute   the 
misfortune  to  a  maternal  impression.     Medical  men  have  thought 
it   worth  while  to  collect  and   publish   many  instances  of  such 
happenings.     But  "  Dr  William  Hunter,  in  the  last  century,  told 
my  father  that  during  many  years  every  woman  in  a  large  lying-in 
hospital  was  asked  before  her  confinement  whether  anything  had 
especially  affected  her  mind,  and  the  answer  was  written  down ; 
and  it  so  happened  that  in  no  instance  could  a  coincidence  be 
detected  between  the  woman's  answer  and  any  abnormal  structure ; 
but  when  she  knew  the  nature  of  the  structure  she  frequently 
suggested  a  fresh  cause."2 

121.  Telegony  is  the  term  applied  to  the  alleged  influence  of  a 
previous  sire.     Thus  if  a  woman  bears  two  children,  the  first  to  a 

1  For  a  more  detailed  discussion  of  the  evidence  furnished   by  syphilis,   see 
§§  416-8. 

2  Darwin,  Animals  and  Plants,  vol.  ii.  pp.  252-3. 


76  THE  LAMARCKIAN  DOCTRINE 

dark  and  the  second  to  a  fair  husband,  then,  if  the  latter  child 
happens  to  be  darker  than  its  father,  she  is  apt  to  attribute  the 
variation  to  the  influence  of  her  first  husband.  Though  still  widely 
credited  by  animal  breeders,  telegony  has  been  disproved  experi- 
mentally, at  any  rate  as  far  as  negative  evidence  can  disprove 
anything,  by  Professor  Cossar  Ewart.1 

122.  Both  maternal  impressions  and  telegony  are  interesting, 
chiefly  as  indications  of  the  curious    looseness   of  thought   and 
expression  which  occasionally  prevails   in    biological    discussion. 
They  were  often  quoted  in  support  of  the  Lamarckian  doctrine ; 
but,  plainly,  they  have  no  bearing  on  it.     In  neither  case  is  it 
alleged  that  the  mother  transmits  her  acquirement  to  offspring. 
In  the  one  case  she  receives  a  mental  impression,  but  the  child  is 
supposed    to   develop   something    entirely   different,    a    physical 
abnormality.     In  the  other  she  receives  a  physical  impression,  and 
the  child    is    said  to  develop  a  physical  character,    but  not  the 
character  the  mother  acquired.     Thus  a  negress  who  has  borne 
a  child   to   a    white   man,    and    who  subsequently  bears  an  ex- 
ceptionally fair  child  to  a  negro,  has  not  herself  become  fair.     In 
brief,  the  alleged  phenomena  do  not  belong  to  the  category  of  trans- 
mitted acquirements.     They  are  marvels  even  more  marvellous. 

123.  As  long  as  we  think  superficially  the  Lamarckian  hypo- 
thesis presents  an  appearance  of  fascinating  simplicity  and  obvious- 
ness.   Since  the  multicellular  organism  is  a  '  unit '  for  most  purposes 
of  life,  it  is  natural  to  regard  it  as  a  unit  from  the  standpoint  of 
heredity — to  think  of  it  as  if  it  were  unicellular,  to  suppose  in 
effect  that  the  parts  of  the  child  are  derived  from  similar  parts  of 
the  parent,  and,  therefore,  that  when  a  character  is  acquired  by  the 
parent,  the  same  character  reappears  in,  is  inherited  by,  the  child. 
If,    in   addition,    we    fail    to   observe   that    the    complex    higher 
animals    fit  their  environments    mainly  because   they  grow  into 
adaptation  to  them  through  the  development  of  use-acquirements, 
it  is  possible  to  use  this  very  fact  of  adaptation  in  an  argument 
intended  to  demonstrate  the  inadequacy  of  Natural  Selection  as  a 
cause  of  evolution.     But  when  we  delve  beneath  the  surface  and 
think  with  precision  in  terms  of  the  germ-plasm  instead  of  vaguely 
in  terms  of  the  individual,  the  simplicity  and  obviousness  vanish, 
and  the  doctrine  becomes  almost  unthinkable.     We  see  that  it 
depends  on  a  number  of  assumptions  which,  to  say  the  least,  are 
wildly  improbable.     Manifestly,  when  an  acquirement  is  said  to  be 
transmitted,  no  real  inheritance  can  occur ;  for  a  character  that  is 

1  See  The  Penycuik  Experiments  (London :  Adam  and  Chas.  Black,  1899). 


SUMMARY  77 

developed  by  the  parent  under  the  influence  of  use  or  injury  is 
profoundly  different  from  one  which  is  developed  by  the  child 
under  the  stimulus  of  nutriment.  The  doctrine  assumes  that  all 
structures  in  all  living  beings  are  capable  of  growth  under  the 
stimulus  of  use,  and  that  the  amount  of  this  growth  is  compara- 
tively trivial ;  whereas  the  truth  is  that  only  some  structures  in 
some  living  beings  can  grow  in  this  way,  and  in  some  types  the 
amount  of  growth  so  made  is  by  far  the  major  part  of  the  total 
normally  achieved.  It  pretends  to  account  for  adaptive  variations, 
but  in  almost  every  instance  a  character  transferred  from  the 
category  of  those  produced  by  use  or  injury  to  that  of  those 
produced  under  the  stimulus  of  nutriment  would  become  less 
adaptive,  and  often  positively  harmful.  It  professes  to  account  for 
evolution,  but,  were  it  true,  every  species  would  drift  swiftly  out 
of  harmony  with  the  surroundings,  and  therefore  to  destruction. 
Except  miracle,  we  can  conceive  no  means  through  which  the 
power  of  transferring  characters  from  one  category  to  another  can 
have  originated.  Lastly,  there  is  massive  evidence  not  only  that 
have  inborn  traits  not  replaced  acquirements,  but  that  the  contrary 
has  happened. 

124.  The  Lamarckian  hypothesis  is  dead  as  an  accepted  inter- 
pretation of  the  facts.  Probably  none  of  the  younger  students  of 
heredity  accept,  or  will  ever  again  accept  it.  Indeed,  so  far  as  I 
am  able  to  judge,  nobody,  even  if  he  happens  to  be  a  professional 
biologist,  now  holds  it  unless  he  is  unaware  of,  or  ignores  much 
that  has  been  published  of  recent  years  on  the  subject.  At 
any  rate,  while  such  arguments  as  those  which  were  used,  for 
example,  by  Spencer  about  the  horns  of  the  elk  are  still  advanced, 
the  reasoning  which  has  demonstrated  their  invalidity  is  invariably 
ignored. 


CHAPTER  V 
VARIABILITY 

Variations  as  distinguished  from  modifications — Spontaneous  variations  as 
distinguished  from  those  due  to  the  direct  action  of  the  environment — Evidence 
of  the  existence  of  the  latter — Discussion  of  the  evidence — Variability  in  uni- 
cellular and  multicellular  organisms. — The  insusceptibility  of  the  germ-plasm 
to  direct  action  of  the  environment — The  fallacies  of  experimental  evidence — 
Variation  in  new  environments — Nearly  all  variations  are  spontaneous — The  cause 
of  spontaneous  variations — The  three  fundamental  laws  of  heredity. 


W1 


125.  "^"^  7"E  dismiss,  then,  the  Lamarckian  doctrine.  The  only 
intelligible  theory  of  evolution  remaining  is  that 
of  Natural  Selection.  Our  task,  then,  is  to  ascer- 
tain^ on  the  one  hand,  whether  this  doctrine  accords  with  all  the 
facts  of  adaptation — is  contradicted  by  none — and,  on  the  other 
hand,  to  discover  the  theory  of  heredity  which  accords  with  it. 
Since  we  are  able  to  account  for  innate  likenesses  between  parents 
and  offspring,1  we  have,  in  effect,  to  study  the  origin  of  innate 
differences,  of  variations. 

126.  The  reader  may  be  reminded  that  a  variation — in  the 
sense  in  which  we  use  the  word,  which  is  that  of  common  scientific 
usage — is  a  difference  between  parents  and  offspring,  due  to  a  differ- 
ence in  germ-plasms.  It  is  not  a  'modification,'  a  difference 
caused  by  an  unequal  play  of  stimuli  on  parent  and  child.  While 
biologists  still  believed  in  the  transmission  of  acquirements,  the 
term  'variation'  was  used  to  indicate  any  difference,  whether 
germinal  or  due  to  an  unequal  play  of  stimuli.  But,  when  the 
Lamarckian  theory  was  being  discarded,  and  the  importance  ot 
distinguishing  between  the  two  kinds  of  differences  was  realized, 
a  tendency  to  limit  the  term  to  differences  founded  on  changes  in 
the  germ-plasm  became  general.  Even  now,  however,  the  word  is 
sometimes  given  unlike  meanings  by  various  writers.  Thus  some 
authors,  still  using  it  in  its  old  sense,  distinguish  by  means  of  an 
adjective  between  "  blastogenetic,  genetic,  or  germinal  variations  " 
(i.e.  variations  properly  so  called)  and  "somatogenic  variations" 
(i.e.  modifications).  Others  imply  that  any  change  in  the  child 

1  See  §  88. 

78 


VARIATIONS  AND  MODIFICATIONS  79 

which  arises  from  a  change  in  the  germ-cell  is  a  variation.  But  it 
is  conceivable,  indeed,  as  we  shall  see,  it  is  certain,  that  the  germ- 
cell  may  be  affected  (e.g.  by  nutrient  fluids  or  by  poisons),  and  the 
child  which  springs  from  it  altered,  while  the  hereditary  poten- 
tialities of  the  germ-/^;;/,  which  passes  on  to  the  descendants, 
remain  unchanged.1  In  such  cases  the  alteration  in  the  child  is 
just  as  much  a  'modification,'  and  just  as  little  transmissible,  as  if 
the  agency  which  produced  it  had  acted,  not  on  the  germ-cell,  but  on 
its  cell-descendants — that  is  on  the  tissues  of  the  child.  Evidently, 
then,  if  we  accept  the  modern  meaning,  and  the  word  variation  is 
to  have  a  signification  sufficiently  clear  and  precise  to  make  it 
valuable  in  science,  it  should  be  limited  to  those  changes  in  the 
germ-plasm  which  mark  real  alterations  of  the  hereditary  ten- 
dencies ;  thus  it  should  not  be  applied  to  those  temporary  alterations 
in  the  well-being  of  the  germ-plasm  which  result  from  changes  in 
nutriment  or  from  the  presence  of  toxins  and  the  like — alterations 
which  may  result  in  modifications  in  the  child  that  springs  from 
the  germ-cell  in  which  they  have  occurred,  but  are  not  reproduced 
by  the  descendants.  It  is  in  this  precise  sense  we  shall  use  the  word. 
127.  Either  variations  are  'spontaneous'  or  else  they  result 
from  changes  in  the  hereditary  tendencies  due  to  the  direct  action 
of  the  environment  on  the  germ-plasm.  By  the  term  spontaneous, 
it  is  not  intended  to  imply  that  variations  ever  arise  without 
antecedent  cause,  but  merely  that  the  cause  or  causes  of  them  are 
inherent  in  the  germ-plasm  itself.  Thus,  if  the  germ-plasm  gained 
or  lost  qualities  as  a  consequence  of  the  normal  nuclear  activity, 
growth,  and  change  which  precede  cell-multiplication,  or  if,  owing 
to  inherent  causes,  the  division  of  it  between  the  daughter-cells 
were  qualitatively  inexact,  the  variations  thus  resulting  would  be 
spontaneous.  Again,  when  offspring  have  two  parents,  a  father 
and  a  mother,2  the  variations  from  one,  or  other,  or  both  parents 
that  may  result  from  that  mingling  of  germ-plasms  which  occurs 
in  the  conjunction  of  sperm  and  ovum,  are  to  be  reckoned  as 
spontaneous,  for  they  do  not  arise  from  the  action  of  the  environ- 
ment external  to  the  germ-plasm.  By  variations  which  result  from 
the  action  of  the  environment  are  meant  those  variations  which 
arise  through  the  direct  and  immediate  action  of  its  surroundings 
on  the  germ-plasm.  In  multicellular  organisms,  especially  warm- 
blooded organisms,  the  cells  of  the  soma  and  the  substances  (food, 
toxins,  etc.)  contained  in  the  nutrient  fluids  constitute  the  main 
effective  part  of  the  environment  of  the  germ-cell  and  its  contained 
1  See  §§  132  and  136.  2  Some  offspring  have  only  one  parent,  see  §  233. 


8o  VARIABILITY 

plasm.  I  use  the  words  '  direct '  and  '  immediate '  because  it  is 
conceivable  that  spontaneous  variations  are  due  indirectly  and 
remotely  to  the  action  of  the  environment,  which,  through  Natural 
Selection  in  the  past,  may  have  so  dealt  with  the  germ-plasm  of 
the  species  as  to  create  a  tendency  to  spontaneous  variability.1 

128.  Normal  offspring  resemble  their  parents  on  the  whole, 
but  differ  from  them  in  detail.     We  have  to  decide  whether  these 
variations  in  details  are  spontaneous  or  caused  by  the  direct  influence 
of  the  environment ',  or,  if  by  both,  in  what  proportion,  as  a  general 
rule,  the  two   kinds  of  variations   occur.      Now  the   offspring   of 
the  same  parents  always  vary,  not  only  from    both  the  parents, 
but  among  themselves.      Thus  even  '  identical '  twins  are  never 
absolutely  alike,  and   the   members  of  a  litter  of  dogs,  pigs,  or 
kittens  often  differ  greatly  in  size,  shape,  colour,  strength,  activity, 
mental  disposition,   length  and  texture  of  hair,  and  every  other 
character.     These  differences  cannot  be  due  to  the  direct  action 
of  the   environment,   for   the   germ-cells,   embryos,    and    foetuses 
existed  from  first  to  last  under  conditions  that  were  practically 
identical.     They  must,  therefore,  be  spontaneous.     At  any  rate,  I, 
for  one,  cannot  believe  that  such  small  differences  of  environment 
as  may  have  existed  before  birth  can  result  in  one  puppy  being 
big  and  black  and  another  small  and  brown,  in  one  being  rough 
and  the   other  smooth-haired,  or  in  one  resembling  the  father, 
another  the  mother,  and  a  third  a  remote  ancestor,  and  so  on. 
Moreover,  it  has  been  observed  that,  when  the  parents  are  the 
same,  differences  between  members  of  the  same  litter  are  just  as 
great  as  those  between  members  of  successive  litters.     It  follows, 
then,   that    some   variations   at   least   are   spontaneous,    and    our 
task  in  the  present  chapter  is  to  ascertain,  not  whether  ALL  variations 
are  due  to  the  direct  action  of  the  environment,  but  whether  AN\ 
variations  are  due  to  it. 

129.  With  the  intention  of  proving  that  variations  are  due  to 
the  direct  action  of  the  environment  a  vast  amount  of  evidence  has 
been  accumulated  by  biologists.     A  little  of  it  is  fairly  conclusive, 
much  is  inconclusive,    and  much   has   no   bearing   on  the  point 
at  issue. 

130.  Zymotic  diseases — malaria,  tuberculosis,  typhoid,  dysentery, 
cholera,  diphtheria,  and  the  like — are  produced  by  different  species 
of  unicellular  organisms.     Bacteriologists  are  able  to  increase  or 
decrease  the  virulence  of  many  diseases  by  altering  artificially  the 
environment  of  the  microbes.     Thus  small-pox,  when  removed  to 

1  See  §  163. 


THE  BIOLOGICAL  EVIDENCE  81 

the  calf,  becomes  cow-pox ;  returned  to  man,  it  is  that  very  different 
and  much  milder  complaint,  vaccinia.  Rabies,  passed  through  a 
succession  of  monkeys,  grows  milder  in  type  for  man  ;  passed 
through  dogs,  more  virulent ;  through  rabbits,  still  more  virulent. 
When  diseases  are  passed  from  one  species  of  animal  to  another, 
they  are  generally  comparatively  mild  for  the  second  species  at 
first,  but  tend  to  become  more  virulent  to  it  the  longer  they  afflict 
it,  till  a  maximum  of  virulence  is  reached.  Therefore  animals  that 
are  affected  by  microbes  that  have  inhabited  their  own,  or  a  nearly 
allied  species,  usually  suffer  more  severely  than  when  the  microbes 
are  derived  from  a  more  alien  source.  The  organisms  of  diphtheria 
and  tuberculosis  may  be  gradually  '  attenuated '  by  cultivation  in 
artificial  media,  those  of  anthrax  quite  quickly  by  heat.  Many 
more  instances  of  the  same  nature  have  been  recorded. 

131.  Medical  men  have  published  voluminous  statistics  proving 
that  diseased  and  intemperate  people  often  have  children  degene~ 
rate   or   defective   physically   or    mentally,   and    that   slum-bred 
children  are,  on  the  average,  inferior  in  physique  to  the  offspring 
of  rural  folk  ;  and  they  have  assumed  that  these  filial  defects  are 
innate  and  due  to  the  parental  ill-health. 

132.  In  his  Presidential  Address  to  the  Zoological  Section  of 
the  British  Association,1   Professor  J.   Cossar  Ewart   maintained 
that  "  there  is  a  considerable  amount  of  evidence  in  support  of  the 
view  that  changes  in  any  part  of  the  body  or  soma  which  affect  the 
general  welfare  influence  the  germ-cells." 

"  It  may  first  be  asked,"  he  added,  "  Does  disease,  in  as  far  as  it 
reduces  the  general  vigour  or  interferes  with  the  nutrition  of  the 
germ-cells,  act  as  a  cause  of  variation  ?  I  recently  received  a 
number  of  blue-rock  pigeons  from  India  infected  with  a  blood 
parasite  (Halteridium),  not  unlike  the  organism  now  so  generally 
associated  with  malaria.  In  some  pigeons  the  parasites  were  very 
few  in  number,  in  others  they  were  extremely  numerous.  The 
eggs  of  a  pair  of  these  Indian  birds  with  numerous  parasites  in  the 
blood  proved  infertile.  Eggs  of  a  hen-bird  with  numerous  parasites 
fertilized  by  a  male  with  few  parasites  proved  fertile,  but  the  young 
died  before  ready  to  leave  the  nest.  An  old  Indian  bird,  however, 
with  comparatively  few  parasites,  mated  with  a  half-bred  English 
turbit,  produced  a  single  bird.  The  half-bred  turbit  has  reddish 
wings  and  shoulders,  but  is  otherwise  white.  The  young  bird  by 
the  Indian  blue-rock  is  of  a  reddish  colour  all  over,  but  in  make 
not  unlike  the  cross-bred  turbit  hen. 

1  See  Nature,  vol.  Ixiv.,  1901. 


82  VARIABILITY 

"  Some  time  before  the  second  pair  of  eggs  was  laid,  the 
parasites  had  completely  disappeared  from  the  Indian  bird,  and 
he  looked  as  if  he  had  quite  recovered  from  his  long  journey  as 
well  as  from  the  fever. .  In  due  time  a  pair  of  young  were  hatched 
from  the  second  eggs,  and  as  they  approached  maturity  it  became 
more  and  more  evident  that  they  would  eventually  present  all  the 
distinctive  points  of  the  wild  rock-pigeon.  The  striking  difference 
between  the  first  birds  of  the  second  nest  might,  however,  be  due, 
not  to  the  malaria  parasities,  but  to  the  change  of  habitat. 

"Against  this  view,  however,  is  the  fact  that  another 
Indian  bird,  infected  to  about  the  same  extent  as  the  mate  of  the 
half-bred  turbit,  counted  for  little  when  mated  with  a  second  half- 
bred  turbit ;  while  two  Indian  birds  in  which  extremely  few 
parasites  were  found  at  once  produced  blue-rock-like  birds  when 
bred — one  with  a  fantail  and  the  other  with  a  tumbler. 

"Another  possible  explanation  of  the  difference  between 
the  bird  of  the  first  and  the  birds  of  the  second  nest  is  that  the 
germ-cells  were  for  a  time  infected  by  the  minute  protozoon 
Halteridium  in  very  much  the  same  way  as  the  germ-cells  of 
ticks  are  infected  by  the  parasite  of  Texas  fever.  But  of  this 
there  is  no  evidence,  for  even  in  the  half-grown  birds  hatched  by 
the  pure-bred  malarious  Indian  rocks  the  most  careful  examination 
failed  to  detect  any  parasites  in  the  blood.  In  all  probability 
Halteridium  can  only  be  conveyed  from  one  pigeon  to  another  by 
Culex  or  some  other  gnat. 

"  These  results  from  pigeons  suffering  from  malaria  seem 
to  indicate  that  the  germ-cells  are  liable  to  be  influenced  by 
fevers  and  other  forms  of  disease  that  for  the  time  being  diminish 
the  vitality  of  the  parents.  Further  experiments  may  show  that 
the  germ-cells  are  influenced  in  different  ways  by  different 
diseases. 

"  Sometimes  the  germ-cells  suffer  from  the  direct  action  of 
their  immediate  environment,  from  disturbance  in  or  around  the 
germ  glands.  If,  for  example,  inflammation  by  the  ducts  or  other 
channels  reaches  the  germ-glands,  the  vitality  of  the  germ-cells 
may  be  considerably  diminished  ;  if  serious  or  prolonged,  the 
germ-cells  may  be  as  effectively  sterilized  as  are  the  bacteria  of 
milk  by  boiling." 

133.  Obviously  Professor  Ewart  assumes  that  if  offspring  alter 
in  consequence  of  an  alteration  in  the  gerrn-^//,  the  change  is 
necessarily  a  variation.  His  experiments  on  fertilization  are 
interesting.  He  found  "  that  when  a  well-matured  rabbit  doe  is 


THE  BIOLOGICAL  EVIDENCE  83 

prematurely  (i.e.  some  time  before  ovulation  is  due)  fertilized  by  a 
buck  of  different  strain,  the  young  take  after  the  sire  ;  when  the 
fertilization  takes  place  at  the  usual  time,  some  of  the  young 
resemble  the  buck,  some  the  doe,  while  some  present  new 
characters,  or  reproduce,  more  or  less  accurately,  one  or  more  of. 
the  ancestors.  When,  however,  the  mating  is  delayed  about  thirty 
hours  beyond  the  normal  time,  all  the  young,  as  a  rule,  resemble 
the  doe.  It  may  be  inferred  that  in  mammals,  as  in  echinoderms, 
the  characters  of  the  offspring  are  related  to  the  conditions  of  the 
germ-cells  at  the  moment  of  conjugation,  the  offspring  resulting 
from  the  union  of  equally  ripe  germ-cells  differing  from  the  offspring 
developed  from  the  conjugation  of  ripe  and  unripe  germ-cells,  and 
still  more  from  the  union  of  over-ripe  germ  cells." 1 

134.  A  species  of  butterfly  is  bright  coloured  in  Germany,  but 
of  a  darker  hue  in  Italy.  Weismann  reared  the  Italian  variety  in 
a  low  and  the  German  in  a  high  temperature.  The  former  became 
lighter,  but  not  so  light  as  the  German  variety  ;  the  latter  became 
darker,  but  not  so  dark  as  the  Italian  type.  Like  Professor  Ewart, 
he  does  not  appear  to  have  ascertained  whether  the  alterations 
were  reproduced  by  subsequent  generations.2  Hoffman  sowed  wild 
plants  very  thickly  in  pots.  After  several  generations  they 
produced  double  flowers  never  observed  before.  Pictet  altered 
the  colour  of  butterflies  by  transferring  the  caterpillars  from  the 
normal  food  plant  to  another.  He  found  that  each  kind  of  abnormal 
food  impressed  characteristic  effects  on  offspring.  These  effects 
persisted  and  increased  for  some  generations,  but  eventually  the 
race  became  adapted  to  the  new  food,  and  thereupon  returned  to 
the  primitive  type.3  "  Dr  Bachrnan  states  that  he  has  seen  turkeys 
raised  from  the  eggs  of  the  wild  species  lose  their  metallic  tints  and 
become  spotted  with  white  in  the  third  generation."  4  Mr  Hewitt 
"  found  he  could  not  breed  wild  ducks  true  for  more  than  five  or  six 
generations,  as  they  proved  so  much  less  beautiful.  The  white 
colour  round  the  neck  of  the  mallard  became  broader  and  more 
irregular,  and  white  feathers  appeared  in  the  ducklings'  wings."5 
Metzger  cultivated  in  Europe  a  tall  variety  of  maize  brought  from  the 
warmer  parts  of  America.  "  During  the  first  year  the  parents 
were  twelve  feet  high,  and  a  few  seeds  were  perfected  ;  ...  in  the 
second  generation  the  plants  were  from  nine  to  ten  feet  in  height 
and  ripened  their  seeds  better.  .  .  .  Some  of  the  seeds  had  even 

1  Loc.  cit.,  p.  482.  2  The  Germ-plasm,  p.  389. 

3  L' Influence  de  I' Alimentation  et  de  I'Humidite  sur  la  Variation  des  Papillons. 

4  Animals  and  Plants,  vol.  ii.  p.  250.  5  Op.  cit.,  vol.  i.  p.  340. 


84  VARIABILITY 

become  yellow,  and  in  their  now  rounded  form  they  approached 
the  common  Europeon  maize.  In  the  third  generation  nearly  all 
resemblance  to  the  original  and  very  distinct  American  parent  was 
lost.  In  the  sixth  generation  the  maize  perfectly  resembled  a 
European  variety." 1  "  Clayton  allowed  six  bean  plants  to  grow  in  a 
spot  where  they  would  catch  all  the  sunshine  of  the  day,  while  six 
other  similar  plants  were  protected  by  a  boarding  which  effectually 
screened  off  the  sun.  When  freshly  gathered  in  October,  the 
weight  of  the  beans  and  the  pods  of  the  exposed  plants  was  to  that 
of  the  protected  as  99 :  29,  whilst  the  weight  of  the  day  beans  was 
as  1 6 :  5.  The  next  year  the  weight  of  the  fresh  beans  and  pods 
obtained  from  the  sunshine-grown  seeds  of  the  previous  year, 
was  half  as  much  again  as  in  the  case  of  the  plants  from  shade- 
grown  seeds,  in  spite  of  the  fact  that  all  of  the  plants  were  now 
grown  in  sunshine  and  under  precisely  similar  conditions.  In 
the  fourth  year  plants  with  an  exclusively  shady  ancestry  pro- 
duced flowers  but  failed  to  mature  fruit."2  European  dogs  are 
said  to  deteriorate  steadily  in  India,  and  English  horses  in  the 
Falklands. 

135.  It  is  unnecessary  to  multiply  examples.  Obviously  some 
of  this  evidence  is  capable  of  an  interpretation  different  from  that 
given  by  its  observers.  For  example,  the  medical  statistics  are 
wholly  inconclusive.  Not  only  diseased  and  intemperate,  but 
healthy  and  temperate  people  have  defective  offspring ;  whereas 
diseased  and  intemperate  people  often  have  normal  children.  It 
has  not  been  shown  that  the  proportion  of  defective  offspring  is 
greater  in  the  one  case  than  in  the  other.3  Even  if  that  were  done 
it  would  still  have  to  be  shown  that  the  parents  were  not  themselves 
defective  before  they  became  drunken  or  diseased;  for  it  is 
roundly  asserted  that  people  naturally  (i.e.  innately)  defective, 
mentally  or  physically,  are  especially  prone  to  intemperance  and 
disease,  and,  of  course,  the  offspring  of  such  people  tend,  in  any 
case,  to  inherit  their  defects.4  Next  it  would  have  to  be  proved 
that  the  defects  of  the  children  were  true  variations,  true  alterations 
of  the  hereditary  tendencies  reproducible  by  descendants,  not 
merely  modifications  caused  by  temporary  injury  (due  to  the  health 
or  habits  of  the  parents)  to  the  germ-cell,  embryo,  or  foetus.  In  the 
case  of  slum-bred  children,  also,  it  has  not  been  shown  that  the 

1  Op.  cit.,  vol.  i.  p.  340. 

2  Vernon,  Variations  in  Animals  and  Plants,  p.  247.  3  See  §§  776-7. 

4  See,  for  example,  Branthwaite,  The  British    Journal  of  Inebriety,  January 
1908. 


THE  BIOLOGICAL  EVIDENCE  85 

defects  are  innate — that  the  defects  would  not  develop  equally  in 
country  children  were  they  transferred  early  in  life  to  the  slums.1 
At  present  the  reader  may  be  inclined  to  regard  these  criticisms  as 
frivolous  and  overstrained,  but  he  will  find  later  there  is  ample 
warrant  for  them. 

136.  Much  the  same  objections  may  be  taken  to  Professor 
Ewart's  inferences.  Evidently  his  birds  acquired  the  disease  in 
their  native  habitat,  and,  since  so  many  or  all  of  them  had  the 
malady,  it  is  doubtless  very  prevalent  there.  Evidently,  again, 
since  the  disease  resembles  malaria,  since  it  travelled  from  India 
in  the  birds,  and  since  so  many  birds  were  suffering  from  it,  it  is 
a  malady  of  long  duration.  If,  then,  it  is  a  cause  of  sterility,  we 
are  left  to  wonder  how,  under  the  conditions,  the  race  has  persisted 
in  India.  But  granting  that  it  is  a  cause  of  sterility,  it  does  not 
follow  that  it  is  a  cause  of  variations.  As  a  fact  Ewart's  experi- 
ments prove  only  that,  like  other  cells,  the  germs,  and  even  the 
germ-plasm  may  be  enfeebled  by  toxins ;  they  do  not  prove 
that  the  hereditary  tendencies  are  thereby  altered.  His  deduction 
might  have  been,  but  was  not,  tested  by  showing  that  the  so- 
called  variations  were  transmissible  to  descendants.  Ewart  himself 
supplies  clear  evidence  that  the  germ-plasm  was  not  altered,  for 
one  of  his  Indian  birds,  which,  when  diseased,  had  offspring 
resembling  the  English  parent,  after  recovery  had  offspring 
resembling  itself.  Evidently  the  germ-plasm  that  remained  in 
this  bird  was  capable  of  recovering  from  its  enfeeblement,  and 
we  have  no  reason  to  suppose  that  the  germ-plasm  which  passed 
from  him  and  entered  a  healthy  female  body  was  less  capable  of 
recovery.  It  certainly  fertilized  the  ovum,  and  the  fact  that  the 
offspring  resembled  the  English  parent  is  no  proof  that  succeeding 
generations  would  not  have  reproduced  the  Indian  characters. 
Professor  Ewart  has,  indeed,  furnished  warrant  for  believing  that 
the  condition  of  the  germ-plasm  at  the  time  of  conjugation  deter- 
mines to  some  extent  the  characters  of  the  offspring,  but  no  warrant 
for  supposing  it  fixes  the  characters  of  subsequent  descendants. 
All  that  is  demonstrated  is  that  enfeeblement  of  germ-plasm  may 
render  latent  for  a  generation  the  characters  of  the  parent  whence 
it  is  derived.  The  force  of  this  objection  is  even  better  seen  in 
the  experiments  by  which  he  influenced  the  characters  of  rabbits. 
In  fact,  his  observations  seem  rather  to  elucidate  the  conditions 
under  which  latency  occurs  than  the  conditions  under  which 
variations  arise.  It  has  long  been  known  that  sexual  characters 

1  See  §§  732-5. 


86  VARIABILITY 

are  transmissible  in  a  state  of  latency  through  parents  of  the 
opposite  sex,1  and  the  Mendelian  experiments  demonstrate  that 
latency  occurs  in  characters  other  than  the  sexual.2 

137.  The   bacteriological  evidence  is  important  and  deserves 
to  be  considered  at  length.     Every  unicellular  organism  is  a  germ- 
cell,  just  as  every  germ-cell  is  in  effect  a  unicellular  organism. 
In  the  last  analysis,  therefore,  the  problems  of  heredity  presented 
by  them  are  similar.     In  other  words,  if  we  think  in  terms  of  the 
germ-plasm,  not  in  terms  of  the  cell-community,  the  problems  o£ 
heredity  presented  by   unicellular  organisms  and  germ-cells  are 
similar.     We  noted  that  the  question  as  to  whether  the  acquire- 
ments of  unicellular  organisms  are,  or  are  not,  inheritable  is  totally 
distinct  from    the  problem  of  the  transmission    of  acquirements 
amongst   unicellular   types.3     Its    real    counterpart   amongst   the 
problems   of  multicellular   life   is   the   question    whether   or   not 
changes  caused  in  the  germ-cells    by  the  direct   action   of  their 
environments  are  inherited  by  descendant  germ-cells.     Obviously 
this  is   a  very  different  problem  from  the  question  whether  the 
particular  changes  caused  by  the  environment  in  the  somatic  cells 
are    inherited   by   the    descendants    of  the    germ-cells,    whether 
the   acquirements   of    Brown    and    Jones   are    inherited    by   the 
descendants   of    Robinson   and    White.      Now    unquestionably   a 
unicellular  organism  or  a  germ-cell  may  be  injured  or  benefited 
by   its    environment.        The  problem   we   have   to  solve,   then,   is 
whether  such  changes  tend  to  be  inherited  by  the  descendant  cells. 
In    other   words   we   have   to  discover  whether  they  necessarily 
or  usually  imply  alterations  (i.e.  variations)  in  the  germ-plasm. 

138.  Of  all  unicellular  organisms  the  disease-producing  (patho- 
genic) microbes  have  been  most  closely  studied,  and  of  all  their 
characters  their  powers  of  offence  and  defence  have  claimed  the 
most   attention.     When    they   enter   a    living   body,    a   man    for 
instance,  a  struggle  ensues  between  them   and   the  cells  of  the 
host.     They,  or   at  least  some  species   of  them,    secrete   toxins, 
soluble  poisons  which  defend  them  from  the  cells,  which  in  turn 
secrete  substances  (enzemes)  poisonous  to  the  microbes.4     If  only 
a  few  microbes  enter  the  body  they  are  destroyed.     Thus  it  has 
been  found    experimentally   that   if  less   than  sixteen  thousand 
virulent  anthrax  bacilli  be  introduced  into  a  normal  young  rabbit, 
they  all  perish.     A  greater  number  multiply  and  cause  disease 
in  a  suspectible  individual,  presumably  because   they   so   poison 
the  cells  of  the  body  that  the  latter  are  unable  to  poison  them. 

1  See  §238.  2  See  §§273  et  seq.  3  See  §§  98  and  431.  4  See  §41 3. 


THE  BACTERIOLOGICAL  EVIDENCE  87 

If  recovery  occurs,  the  cells  of  the  body  gradually  become  accus- 
tomed to  the  toxins,  which  are  digested  by  them.1  They  obtain 
the  upper  hand ;  the  individual  acquires  immunity ;  the  microbes 
are  destroyed  ;  and,  as  a  consequence,  the  sufferer  is  no  longer 
infective  to  his  fellows. 

139.  A  human  race  undergoes  evolution  against  such  a  disease 
as   measles   or  diphtheria   when  it   becomes  more  resistant.      It 
becomes    more    resistant    when    successive   generations   become, 
through  Natural  Selection,  more  capable  of  reacting  to  the  toxins 
and  so  'acquiring'  immunity.      The  germ -plasm  becomes  such 
that  under  the  stimulus  of  nutriment  individuals  develop,  who,  if 
they   experience   the   disease,   are   able   to   develop   further    and 
'  acquire  '  actual  immunity.     Therefore,  while  the  power  of  acquir- 
ing immunity  is  an    '  inborn '  character,  the  immunity  itself  is  a 
'  use-acquirement.'      That  is  to  say,  the  individual  who  acquires 
immunity  becomes  usedte  the  disease  (develops  under  its  stimulus), 
just  as  the  muscles  of  the  athlete  become  used  to  endure  fatigue, 
or  the  skin  of  the  palm  to  endure  rough  labour.     The  process  of 
evolution  is  a  long  and  a  slow  one,  extending  over  many  genera- 
tions.     The  final  effect,  as  we  see,  is  not  the  creation  of  a  race 
the  individuals  of  which  resist  infection  (i,e.  are  innately  immune), 
but  the  creation  of  a  race  the  individuals  of  which  tend  to  recover 
from   infection  (i.e.  acquire  immunity).     This  is  not  true  of  all 
diseases,  but  it  is  true  of  the  majority.2     We  shall  study  the  subject 
at  length  in  a  subsequent  chapter.     Meanwhile  the  points  on  which 
I   wish  to  lay  stress  are  (i)  that  human  races  become  adapted 
through  Natural  Selection  to  the  presence  of  diseases,  and  (2)  that 
in  the  case  of  many  diseases  this  adaptation  consists  in  a  swift 
reaction  to  infection — a  reaction  so  swift  that  the  cells  of  an  affected 
individual  begin  to  produce  their  enzymes  as  soon  (within  a  few 
minutes)  as  the  microbes  make  their  presence  felt.     This  produc- 
tion of  enzymes  is  a  step  on  the  road  to  immunity — but  only  a 
step,  for  after  the  enzymes  disappear  more  or  less  completely  from 
the  body,  the  immunity  remains.     Here  we  have  an  instance  of 
the   high   organism  making   a   pre-eminently  advantageous   use- 
acquirement  in  spite  of  the  fact  that  its  cells  are  continually  bathed 
in  and  injured  by  the  toxins. 

140.  By  skilful  management  it  is  possible  to  alter  artificially 
the   characters  of  unicellular  species.      Thus  certain  saprophytic 
organisms   (which   normally    obtain    their    nutriment   from    dead 
organic  matter)  may,  under   favourable  conditions,  be  gradually 

1  See  §§  410  et  seq.  2  See  chapter  xiii. 


88  VARIABILITY 

'  trained  '  to  attack  living  beings  ;  that  is,  they  may  be  trained  to 
produce  toxins  so  protective  to  themselves,  and,  therefore,  so 
injurious  to  the  cells  of  the  host,  that  they  are  able  to  live  and 
multiply  in  the  dangerous  environment  till  the  host  dies  or  acquires 
immunity.  This  training,  this  conversion  of  a  saprophytic  into  a 
parasitic  type,  always  involves  placing  the  microbes  in  contact 
with  living  cells.  For  example,  streptococci,  which  are  normally 
saprophytic,  may  be  rendered  very  virulent  (i.e.  capable  of  main- 
taining existence  in  living  tissues)  by  passage  through  a  series  of 
animal  hosts,  but  cannot  otherwise  be  rendered  virulent.  On  the 
other  hand,  purely  parasitic  organisms  may  be  trained  to  sapro- 
phytic habits  of  life.  If  placed  in  a  suitable  non-living  medium  (e.g. 
broth)  where  they  are  no  longer  persecuted  by  the  cells,  they  slowly 
lose  their  toxins,  and,  while  becoming  more  capable  of  existing  in 
that  particular  medium,  become  less  capable  of  maintaining  them- 
selves in  the  living  body.  In  either  case  the  change,  since  it 
increases  in  successive  generations  till  fitness  to  the  new  environ- 
ment is  achieved,  is  both  germinal  and  adaptive.  So  close  is  the 
adjustment  to  the  environment  that,  usually,  each  microbic  disease 
is  limited  to  a  single  species  of  animal.  Thus  most  human  diseases 
are  peculiar  to  man.  When  more  than  one  species  is  attacked  by 
the  same  disease,  as  is  often  brought  about  experimentally,  the 
microbes  tend  to  separate  into  varieties  or  races,  each  of  which  is 
most  virulent  (i.e.  best  adapted  to,  best  protected  in)  the  species  it 
has  made  its  host.  Each  parasitic  species  has  its  peculiar  toxin, 
a  means  of  defence  which  is  always  the  same  for  the  same  species, 
but  which  differs  from  that  of  every  other  species,  as  may  be  judged 
from  the  symptoms  of  the  maladies  they  produce.  Thus,  strep- 
tococci always  produce  the  same  symptoms,  the  same  toxins,  when 
they  become  parasitic.  The  existence  of  the  toxin,  a  very  complex 
chemical  substance,  implies  a  remarkable  producing  apparatus. 
The  evolution  from  saprophyte  to  parasite  is  mainly  the  evolution 
of  this  apparatus.  Unless  we  assume  that  the  microbes  of  disease, 
highly  specialized  organisms,  were  miraculously  created  to  afflict 
the  higher  species,  we  must  assume  that  they  were  all  evolved  from 
saprophytic  types. 

141.  Now  we  reach  the  problem  as  to  the  mode  by  which 
saprophytic  species  become  parasitic.  It  is  probable  that 
all  unicellular  species,  even  the  saprophytes,  have  some  sort  of 
toxins  by  means  of  which  they  dissolve  and  digest  their  food  or 
protect  themselves  from  other  unicellular  organisms,  and  which, 
like  the  saliva  of  snakes,  is  capable  of  undergoing  evolution  till  it 


THE  BACTERIOLOGICAL  EVIDENCE  89 

becomes  poisonous  to  other  forms  of  life.1  Saprophytes  cannot, 
under  normal  circumstances,  contend  against  the  living  cells  of 
multicellular  types ;  but  that  the  toxins  are  strong  in  at  least 
some  of  their  species  is  proved  by  the  fact  that  the  organisms,  for 
example,  which  cause  putrefaction  in  dead  bodies  may,  under 
favourable  conditions,  infect  and  by  poisoning  destroy  men  and 
other  animals.2  Unicellular  organisms  multiply  very  quickly,  as 
may  be  judged  by  the  rapidity  with  which  an  epidemic  of  infectious 
disease  may  sweep  a  large  and  populous  country.  Many  genera- 
tions elapse,  therefore,  even  under  the  most  favourable  experimental 
conditions,  before  a  saprophytic  species  becomes  truly  parasitic. 
Now,  in  this  passage  from  an  environment  to  which  they  are 
adapted  to  another  which  at  first  is  very  unfavourable,  do  the 
microbes  make  useful  4  acquirements '  which  are  '  transmitted '  and 
accumulated  in  descendants  ?  Or  do  they  alter  through  the  Natural 
Selection  of  favourable  spontaneous  variations  ?  The  former  is  the 
accepted  hypothesis.  Indeed,  bacteriologists  do  not  seem  aware 
that  there  is  an  alternative.  Reasoning  from  the  analogy  of 
the  human  being,  they  suppose,  in  effect,  that  microbes  are  able 
to  make  advantageous  acquirements  under  the  stimulus  of  use,  and, 
further,  that,  being  unicellular,  they  are  capable  of  transmitting 
these  acquirements  to  offspring,  so  that  the  latter  start  develop- 
ment where  the  parents  finished. 

142.  But  it  is  necessary  to  exercise  a  little  scientific  imagination. 
The  power  of  making  use-acquirements  is  apparently  a  late  product 
of  evolution,  limited  to  the  higher  species,  in  which  alone  it  is  per- 
ceptible. At  any  rate  we  have  no  right  to  assume  thus  easily  that 
lowly  microbes  possess  it.  Moreover,  since  the  microbes  of  disease 
begin  by  multiplying  and  flourishing  greatly  in  an  infected  person, 
manifestly  they  have  at  first  much  the  best  of  the  struggle,  and 
would  keep  it  did  they  grow  stronger  under  the  stimulus  of  use. 
Indeed,  it  is  evident  that,  if  microbes  not  only  made  use-acquire- 
ments but  transmitted  them,  then,  since  their  multiplication  is  so 
rapid,  their  virulence  would  soon  become  so  exalted  that  the 

1  The  evolution  of  a  toxin  implies  the  power,  not  only  of  producing  it,  but 
of  resisting  it.     Thus  the  cells  of  the  poison  gland  of  the  snake  are  immune  to 
the  venom,  the  cells  of  the  alimentary  canal  are  resistant  to  the  digestive  ferments, 
the  body-cells  to  the  poisons  which  destroy  the  microbes.     So,  also,  the  microbes 
are  resistant  to  their  own  toxins. 

2  It  is  said  that  the  carnivora  are  particularly  immune  to  septicaemia.     If 
this  is  true,  it  is  an  interesting   example  of  special   evolution.     Owing  to  the 
nature  of  their  food  and   the   wounds  they  are  apt  to  receive  in  pursuit  of  it, 
carnivora  are  particularly  exposed  to  infection. 


90  VARIABILITY 

higher  species,  which  can  make  but  cannot  transmit  acquirements, 
could  not  contend  against  them  and  would  soon  become  extinct. 
Again,  the  human  being  is  capable  of  making  only  such  use- 
acquirements  as  evolution  has  fitted  his  race  to  develop.  The 
microbes,  while  they  are  becoming  parasitic,  are  in  an  entirely  new 
and  unfavourable  environment,  in  which  they  are  exposed  to  poison- 
ing and  enfeeblement  through  the  enzymes  secreted  by  the  cells 
of  the  host.  Evolution  has  not  adapted  them  to  make  the  right 
acquirements,  any  more  than  it  has  adapted  human  beings  to  make 
acquirements  fitting  them  for  flight  or  for  life  under  water. 
Under  the  conditions,  what  sort  of  acquirements  could  they  make 
which  would  enable  them  to  produce  stronger  and  stronger  and, 
therefore,  different  toxins,  and  so  protect  themselves  from  the  cells  ? 

143.  It  is  conceivable  that  the  toxins  might  in  some  way  be 
enfeebled  by  injury  to  the  producing  apparatus  and  that  this  injury 
might  be  transmitted  and  so  accumulated  in  subsequent  genera- 
tions till  the  microbes  perished ;  but  to  believe  that  they  are  ever 
strengthened,  that   the  producing  apparatus  of  the  individual  is 
improved  by  the  accidental  effects  resulting  from  the  direct  action 
of  the  environment,  is  to  believe  in  a  coincidence,  a  'fluke'  so 
remarkable  that  it  amounts  to  miracle — a  miracle  that  must  have 
happened   to   every   species   of    pathogenic    microbe   during   its 
transition  from    saprophyte   to    parasite,  and   which   the   human 
operator  is  able  to  initiate  at  will  by  placing  saprophytic  species 
in  contact  with  living  cells,  a  miracle  as  marvellous  as  if  chance 
blows  of  a  hammer  on  pieces  of  metal  had  produced  and  fitted 
together  a  delicate  and  elaborate  machine. 

144.  In  brief,  if  saprophytic  microbes,  while  becoming  parasites, 
are  in  any  way  affected  by  their  new  environments — and  doubtless 
they  are  affected — then,  since  they  neither  cause  the  extinction  of 
the  species  they  attack  nor  themselves  become  extinct,  it  is  certain 
that  their  acquirements  are  not  transmitted.     The  notion  that, 
like  the   higher  animals,  they  are  able  to  make  use-acquirements, 
is  a  mere  guess,  unsupported  by  any  evidence,  but  opposed  by 
much.     Even  were  the  guess  correct,  then,  since  the  higher  or- 
ganisms do  not  make  acquirements  which  evolution  has  not  fitted 
them  to  develop,  it  is  hard  to  understand  how  unicellular  organisms 
could  react  in  a  way  that  enabled  them  to  meet  contingencies 
never  before  experienced  by  the  race.    The  analogy  between  them 
and  the  higher  animals,  therefore,  is  strained  and  inaccurate  at  all 
points. 

145.  Consider,  now,  the  contrary  hypothesis,  that  saprophytic 


THE  BACTERIOLOGICAL  EVIDENCE  91 

species  become  adapted  to  a  parasitic  existence  through  the  Natural 
Selection  of  spontaneous  variations.  Doubtless  unicellular  organ- 
isms, like  the  higher  types,  vary  spontaneously.  If  that  be  admitted, 
then,  presumably,  in  the  struggle  with  the  cells,  the  microbes  with 
the  weaker  defensive  powers,  the  weaker  toxins,  or  the  weaker 
powers  of  producing  toxins  under  unfavourable  conditions,  tend  to 
perish,  while  those  with  the  stronger  powers  tend  to  survive.  In 
that  case  evolution  must  follow  till  the  saprophytic  race  becomes 
adapted  to  a  parasitic  habit  of  life,  after  which  it  would  be  maintained 
in  adaptation  by  the  same  process  of  selection.  The  facts  that 
microbic  species  evolve  virulence  only  when  in  a  position  to  be 
selected  by  living  cells,  that  this  virulence  and  their  other  germinal 
changes  adapt  them  precisely  to  the  particular  species  of  animal 
they  attack,  and  that  they  tend  invariably  to  lose  the  adaptation 
(i.e.  undergo  retrogression)  when  no  longer  in  a  position  to  be  so 
selected,  that  these  changes  in  both  directions  are  continuous  and 
so  gradual  that  many  generations  must  come  and  go  before  they 
are  completed,  and  that  they  proceed  no  further  than  enables  the 
species  to  persist  in  the  new  environment,  are  so  highly  significant 
that  we  have  no  alternative  but  to  attribute  them,  like  the  adaptive 
changes  of  the  higher  species,  to  selection  on  the  one  hand  or 
cessation  of  it  on  the  other.  They  are  too  adaptive  to  be  due  to 
any  other  cause.  They  fit  the  many  and  diverse  species  of  uni- 
cellular parasites  too  closely  to  their  environments  to  be  results  of 
mere  coincidence,  of  mere  accidental  effects,  produced  by  the 
direct  action  of  the  environment. 

146.  The  belief  that  the  increasing   virulence  of  saprophytic 
organisms,  when    they  are   becoming  parasitic,   results  from  the 
direct  action  of  the  environment  on  their  germ-plasm,  is  one  of  those 
*  obvious '  inferences  which,   when  all  the  evidence  is  taken  into 
account,  are  found  to  rest  on  a  series  of  impossible  assumptions. 
Here,  as  always    when    considering   any   complex   and   difficult 
problem,  we  cannot  link  together  all  the  evidence  unless  we  make 
a  rigorous  deductive  inference  of  consequences  and  follow  it  by  an 
appeal  to  reality.     The  generalization  that  microbic  species  change 
adaptively  when  placed  under  right  conditions  in  changed  environ- 
ments is  really  '  obvious ' ;  it  is  an  *  immediate '  inference.     The 
generalization  that  they  change  because  their  germ-plasm  is  directly 
affected  by  the  environment  is  not  really  obvious,  and  must  be 
tested.     When  the  test  is  made,  when  we  do  not  shirk  the  hard 
thinking  necessary,  it  is  seen  to  be  obviously  inaccurate. 

147.  Selection  affords  an  explanation  of  the  adaptive  changes 


92  VARIABILITY 

of  microbic  species  at  once  probable  and  in  accord  with  all  we 
know  of  nature.  Studying  these  changes,  it  becomes  evident  that 
Natural  Selection  is  operative  only  under  certain  conditions.  The 
germ  -  plasm  must  be  variable ;  but  it  must  be  spontaneously 
variable,  not  variable  under  the  direct  action  of  the  environment. 
Spontaneous  variations,  occurring  all  round  the  specific  mean, 
afford  materials  for  Natural  Selection  and  tend  to  enable  the  species 
to  meet  all  contingencies.  But  variations  caused  by  the  direct 
action  of  the  environment  have  an  opposite  effect.  Under  condi- 
tions nearly  the  same  for  all  the  individuals  exposed  to  them,  they 
cannot  occur  all  round  the  specific  mean,  but  in  one  general 
direction  only.  Therefore  they  cause  a  drift,  which  may  or  may 
not  be  adaptive,  but  which,  since  a  new  environment  is  usually 
unfavourable  and  therefore  injurious,  can  be  adaptive  only  as  a 
most  unlikely  coincidence.  Even  if  such  a  drift  were  favourable 
at  first,  the  accumulation,  the  exaggeration  of  it  during  succeeding 
generations  would  be  sure  ultimately  to  ruin  the  co-adaption  of 
parts  and  functions  and  so  render  it  unfavourable ;  for  there  is  no 
imaginable  reason  to  suppose  that  if  such  a  drift  occurred  in 
ancestors  it  would  not  continue  in  descendants.  Virulence  is  not 
the  only  adaptation  found  in  the  microbe.  The  whole  organism 
is  compounded  of  adaptations,  every  one  of  which  is  co-adapted  to 
all  the  others.  Except  by  the  theory  of  evolution  through  Natural 
Selection  it  is  as  hard  to  account  for  any  of  them  as  it  is  to  account 
for  virulence.  As  we  see,  Natural  Selection  cannot  control  a  drift 
in  which  every  individual  participates.  Only  in  one  way  can  it 
be  prevented — by  the  germ-plasm  becoming  highly  insusceptible, 
highly  resistant  to  the  direct  action  of  the  environment.  We  are 
driven^  then,  to  the  conclusion  that  the  germ-plasm  is  both  spon- 
taneously variable  and  highly  resistant  to  the  direct  action  of  the 
environment.  In  other  words,  we  must  believe  that  in  any  species 
that  is  not  undergoing  extinction,  spontaneous  variations  greatly 
preponderate  over  those  which  are  caused  by  the  direct  action  of 
the  environment. 

148.  The  evidence  is  conclusive  that  the  germ-plasm  of  all 
persistent  species  possesses  a  high  power  of  resisting  enforced 
change.  For  example,  some — probably  all — human  diseases  are  of 
great  antiquity.  Descriptions  of  them  written  two  or  three 
thousands  of  years  ago  are  accurate  for  the  present  day.  During 
all  that  time,  though  exposed  to  enzymes  and  other  potent 
influences,  the  microbes,  minute  atoms  of  naked  protoplasm, 
have  not  altered  appreciably.  Fitted  closely  to  a  stable  environ- 


THE  INSUSCEPTIBILITY  OF  THE  GERM-PLASM      93 

ment,  the  human  being,  they  have  been  stable.     They  have  not 
drifted. 

149.  There  is  nothing  especially  magical  or  mysterious  about 
this   germinal    power    of    resisting    enforced    change.     There   is 
abundant  evidence  that  it  exists.     If  it  did  not  exist  no  species 
could  persist.     But,  when  we  say  that  it  exists,  we  do  not  imply 
that  the  germ-plasm  is  incapable   of  being  injured,  incapable  of 
enfeeblement,  or  death,  or  alteration  of  its  hereditary  tendencies. 
We  imply  merely  that  such  enforced  alteration  of  the  germ-plasm 
of  a  species  that  has  been  fitted  by  evolution  to  its  environment  is 
usually  an  injury,  and  that  the  evidence  is  that  when  the  injury  is 
severe  enough  to  cause  alteration  of  the  hereditary  tendencies,  it  is 
usually  severe  enough  to  cause  the  death  of  the  germ-plasm  also. 
In    other   words,  we   imply   that   the    hereditary   tendencies   are 
implanted  in  the  germ-plasm  as  firmly,  or   almost   as   firmly  as 
life  itself.     Indeed  collectively  they  are  the  life  ;  because  of  them 
the  individual  (and  the  germ-plasm)  absorbs  nutriment,  excretes 
waste-material,  grows,  multiplies,  and  so  forth. 

150.  The   power    to    resist    enforced    change   is   essential   to 
existence.     Presumably,    therefore,    it    is,    like     other     essential 
characters,  a  product  of  evolution.     It  is,  at  least,  probable  that 
just   as   individual    unicellular   organisms   vary  as  regards   other 
particulars,  so  they  vary  as  regards  the  power  of  their  germ-plasms 
to  resist  enforced  change.     If  this  power  be  weak  the  germ-plasm 
tends  to  be  destroyed  or  altered  by  the  influences  to  which  it  is 
inevitably  exposed.     The  descendants  of  the  altered  individuals,  if 
there  be  any,  inheriting  the  weak  resisting  power,  tend  to  be  still 
more   changed    and   ultimately   to    be    eliminated.     But,   if  the 
resisting   power  be   great,  and    if  individuals  vary  as  regards  it, 
while   at   the   same    time    spontaneous    variations    occur   in   all 
directions,  the  race  tends  to  survive ;  for  in  that  case  there  is  no 
inevitable   drift ;  natural   selection   has   scope,  and   the   resisting 
power  tends  to  grow  stronger  with  selection.     The  conclusion  we 
reach,  then,  is  that  Natural  Selection  has  established  and  maintains 
the  high  insusceptibility  of  the  germ-plasm  to  the  direct  action  of 
the  environment.1 

151.  Turn,  now,  to  multicellular  animals  and  plants.     Not  only 

1  Interesting  evidence  of  the  stability  of  the  germ-plasm  of  unicellular  organ- 
isms is  furnished  by  Dr  Pearl  in  his  study  of  Paramcecium  caudatum.  These 
organisms  multiply  for  many  generations  without  conjugation.  But  at  intervals 
conjugant  individuals  appear.  "  Dr  Pearl  grew  Paramcecia  under  much  variety 
of  environment,  and  found  that  the  non-con jugant  type  was  highly  correlated 
with  the  environment  and  the  conjugant  type  singularly  little  affected  by  the 


94  VARIABILITY 

the  germ-cell  but  every  cell  of  the  community  is  a  unicellular 
organism.  We  may  take  the  human  being,  as  the  type  best  known 
to  us,  for  an  example.  Consider  first  his  somatic  cells.  From  the 
moment  the  fertilized  ovum  begins  to  proliferate  to  the  death  of 
the  aged  man,  strong  influences — want,  plenty,  disease,  health, 
hardship,  alcohol,  and  so  forth — play  upon  the  cells  ;  yet  each  cell 
comes  true  to  its  type.  Thus  all  sorts  of  stimulants  and  irritants 
may  act  on  the  skin-cells  and  change  them  greatly ;  but,  when  the 
cause  of  change  is  removed,  the  hereditary  tendencies  are  found  to 
be  unaltered,  for  the  young  cells  develop  into  skin-cells  of  quite 
the  old  kind.  I  have  transferred  clippings  from  an  old  man's  skin 
to  the  scalded  and  denuded  arm  of  a  young  woman,  and  they  have 
grown  with  all  the  vigour  of  youth.  If  a  lymphatic  gland  be 
diseased  (e.g.  tuberculous)  for  a  score  of  years,  and  recovery  then 
occurs,  the  cells  are  still  typical  of  their  kind.  Disease  enfeebles 
cells,  but  recovery  from  disease  is  evidence  of  the  stability  of  their 
hereditary  tendencies.  Were  the  latter  easily  altered,  there  could  be 
no  recovery,  and  every  attack  of  measles  or  chicken-pox,  maladies 
in  which  toxins  are  abundant  and  in  which  the  enfeeblement  of 
the  cells  is  shown  by  the  disturbance  of  function,  would  be  fatal. 
Consider  the  cells  which  line  the  alimentary  canal  and  the  extra- 
ordinary variety  of  influences  to  which  they  are  subjected.  Life 
could  not  exist  if  the  germ-plasm  (idio-plasm)  were  not  resistant. 
Evidently,  then,  as  a  condition  essential  to  the  survival  of  the 
individual  and  the  persistence  of  the  species,  somatic  cells  hold 
their  hereditary  tendencies  with  extraordinary  tenacity — with  a 
tenacity  as  great  as  that  displayed  by  the  microbes  of  disease. 

152.  Further  and  very  decisive  evidence  is  afforded  by  the 
extreme  stability  of  plants  when  propagated  by  slips  and  suckers. 
Centuries  may  elapse,  the  plant,  continuously  so  propagated,  may 

environment.  The  whole  inquiry  was,  of  course,  undertaken  to  illustrate 
Weismann's  position,  that  while  acquired  characters  are  not  inherited,  the  en- 
vironment can  influence  inheritance  when  one  cell  is  both  soma  and  germ.  In 
biology  it  has  become  almost  axiomatic  to  assume  that  the  Protozoa  can  inherit 
acquired  characters  owing  to  this  identity,  while  in  the  Metazoa  the  acquired 
character  of  the  soma  is  at  the  very  least  not  usually  inherited.  Dr  Pearl  brings 
out  the  all-important  point  that  the  gamete  in  Paramoecium  is  not,  like  the  non- 
conjugant  cell,  markedly  influenced  by  the  environment"  (Professor  Karl 
Pearson,  Nature,  Oct.  18,  1906,  p.  609).  Mr  H.  S.  Jennings  has  also  published 
observations  on  Paramoecium.  He  says  nothing  concerning  conjugant  indi- 
viduals, terms  all  new  characters  variations,  and  concludes,  "  In  order  that  it 
may  be  inherited  (by  more  than  one  of  the  progeny),  a  characteristic  must  be  the 
result  of  such  a  modification  of  the  mother  cell  as  will  cause  it  to  behave  in  a 
certain  way  at  reproduction."  Apparently  he  means  that  spontaneous  variations 
tend  to  be  transmitted,  but  not  acquirements. 


THE  STABILITY  OF  THE  GERM-PLASM  95 

be  grown  in  all  the  quarters  of  the  globe,  yet  usually  no  appreci- 
able change  is  observable.  Even  when  a  change  is  seen  it  is 
generally  a  mere  '  modification,'  for  the  plant,  if  restored  to  its 
ancestral  environment,  resumes  the  original  form.  '  Bud  variations ' 
occur,  it  is  true,  but  they  are  comparatively  very  few,  and  we  have 
little  reason  to  believe  that  they  are  due  to  the  direct  action  of  the 
environment.  Thus,  when  a  nectarine  appears  on  a  peach  tree, 
it  is  more  likely  that  the  change  in  the  branch  that  bore  it  was 
spontaneous  than  that  it  was  caused  by  direct  action  ;  for  the 
latter  would  imply  that  the  environment  of  that  one  branch  differed 
amazingly  from  the  environments  of  the  other  branches. 

153.  The  germ-plasm  of  the  microbe  is  very  complex  ;  but  more 
complex  to  an  almost  infinite  degree  is  the  germ-plasm  of  such  a 
being  as  man.     The  descendant  cells  of  the  fertilized  ovum  are  not 
mere  copies  of  that  ancestor,  but  members  of  a  vast  community  in 
which  there  is  great  diversity  of  form  and  function,  and  in  which 
every  cell  takes  its  appointed  place  and  does  its  predestined  work. 
Presumably  the  orderly  complexity  of  the  body,  with  its  immense 
ramifications   of  large   and   small   blood-vessels,   lymphatics   and 
nerves,  its  organized  groups  of  muscle,  blood,  gland,  and  nerve 
cells,    its    skin,    bone,    and    cartilage,    indicates   a   corresponding 
complexity  of  the  germ-plasm.     Yet,  though  this  germ-plasm  is 
constantly  exposed  to  all  sorts  of  potent  influences  (e.g.  toxins),  and 
has  been  so  exposed  for  thousands  of  generations,  so  great  is  its 
stability  that  all  this  great  complex  and  even  many  developmental 
processes  which  date  back  to  millions  of  years  before  the  evolution 
of  the  vertebrate  type  are  reproduced  with  unfailing  accuracy  by 
every  normal  individual.     Quite  apart  from  the  fact  that  Natural 
Selection  would  have  no  scope  if  the  hereditary  tendencies  drifted 
this  way  or  that  at  the  mercy  of  the  environment,  it  is  evident  that 
no  complex  type  could  maintain  the  regular  development  and  the 
co-adaptation  of  its  parts,  unless  the  germ-plasm  were  endowed 
with  very  great  resisting  power. 

1 54.  Amongst  multicellular  organisms  selection  occurs  in  every 
stage  of  development,  amongst  germ-cells  and  embryos  as  amongst 
adults.     Germ-cells,  like  unicellular  organisms,  are  fitted  to  their 
environments    by    characters    which    depend    on    the    hereditary 
tendencies   carried    by   the   germ-plasm.      As   is   proved    by   the 
variations  of  the  individuals  that  develop  from  them,  they  vary 
amongst  themselves.     They  are  in  competition  with  one  another, 
some  being  better  adapted  for  survival  and  the  successful  perform- 
ance of  their  functions  than  their  fellows ;  some  having  more  and 


96  VARIABILITY 

some  less  resistant  germ-plasm.  Granting  that  species  have  arisen 
through  Natural  Selection,  then  the  hereditary  potentialities  which 
enable  the  germ-cells  to  develop  into  higher  individuals  (embryos 
and  adults)  are  of  course  due  to  selection  occurring  amongst  the 
latter ;  but  the  characters  that  fit  them  to  their  own  environments, 
for  example  the  locomotory  tail  of  the  spermatozoon,  are  equally  of 
course  due  to  selection  occurring  amongst  themselves.  The  selection 
that  maintains  the  stability  of  the  germ-plasm,  therefore,  falls  first 
of  all  on  the  germs  which  cannot  survive  as  cells  if  the  germ-plasm 
is  much  altered,  or  develop  into  higher  organisms  if  it  is  more  than 
a  little  altered.  Evolution  is  never  perfect ;  it  is  probable,  therefore, 
that  many,  perhaps  very  many,  germs  vary  unfavourably  in  this 
particular  and  perish,  and  that  to  this  circumstance  is  due  the  fact 
that  evidence  of  germinal  alteration  resulting  from  the  direct  action 
of  the  environment  is  rarely  found  amongst  adult  individuals. 

155.  Germ-cells  are  very  numerous  amongst  the  higher  animals, 
though  the  number  of  possible  offspring  is  small.     Thus,  the  germ- 
cells  of  such  an  organism  as  man  exceed  a  million-fold  the  number 
of  his  children.     This  superabundance,  like  all  other  characters  of 
the  species,  is,  presumably,  an  adaptation.     According  to  accepted 
doctrine    it    serves   to    ensure   fertilization.      But    nature    is   very 
parsimonious  of  her  materials,  and  when  we  remember  the  per- 
fection of  her  adaptations  (e.g.  the  eye,  the  ear,  or  the  digestive 
organs),  the  device  of  providing  a  vast  multitude  of  cells  in  order 
to  secure  the  fertilization  of  a  very  few  seems  so  unnecessarily 
wasteful  and  clumsy  as  to  awaken  a  suspicion  of  the  correctness 
of  the  interpretation.     Such  a  device  may  be  necessary  when  the 
germ-cells  are  scattered  broadcast  in  the  environment  and  meet 
by  chance,  as  in  the  case  of  some  plants,  but  hardly  when  they 
enter  a  special  receptacle  in  the  body  of  the  female.     It  seems  not 
improbable,  therefore,  that   the  function  of  the  apparent  super- 
abundance is  to  provide  materials  for  a  selection  which  serves, 
above  all,  to  maintain  the  resisting  power  of  the  germ-plasm.     At 
any  rate  material  in  which  such  a  selection  can  occur  is  provided 
as  abundantly  by  the  higher  animals  as  by  the  lower. 

156.  Leaving  aside  the  question  as  to  how  precisely  the  high 
insusceptibility  of  the  germ-plasm  has  been   evolved,  there  can, 
as  I  say,  be  no  doubt  of  its  existence.     But  though  the  germ-plasm 
possesses  high  powers  of  resisting  enforced  change,  though  death 
usually  accompanies  such  change,   it  does  not  follow  that  con- 
ditions   cannot   be   found   in    which   the    germ-plasm    is   altered 
and    yet    not    destroyed.     Thus,    Clayton's    beans    progressively 


THE  DIRECT  ACTION  OF  THE  ENVIRONMENT      97 

deteriorated  when  placed  in  the  shade,  as  do  European  dogs  in  India 
and  horses  in  the  Falklands.  But  in  all  these  cases  the  change, 
when  clearly  germinal,  when  it  is  transmitted  and  so  increases  from 
generation  to  generation,  is  ever  a  deterioration,  not  an  adaptation. 
The  germ-plasm  in  those  cells  that  develop  into  offspring  is  altered 
and  injured,  but  not  sufficiently  to  cause  its  death  or  even  to 
prevent  the  development  of  the  individual.  Now,  obviously,  the 
deterioration  cannot  continue,  generation  after  generation,  in- 
definitely. If  not  checked,  the  race  must  perish  eventually. 
But  there  are  plants  that  dwell  in  the  shade,  there  are  native 
races  of  dogs  in  India,  and  some  varieties  of  horses  flourish  in 
climates  severer  than  that  of  the  Falklands,  and  so  on.  They 
are  said  to  have  become  'acclimatized,'  to  have  reached  an 
'  equilibrium ' — meaningless  terms  unless  it  be  explained  what 
they  imply.  They  really  imply  adaptation,  an  essential  feature 
of  which  consists  in  the  germ-plasm  becoming  insusceptible  to  the 
direct  action  of  the  environment.  Thus  if,  amongst  Clayton's 
beans,  there  had  been  any  germs  the  plasm  of  which  had  so  varied 
as  to  be  unaffected  by  shade,  then,  since  he  obtained  seed  in  the 
first  three  generations,  he  could  have  established  by  Natural 
Selection  a  race  as  capable  of  existing  away  from  the  influence  of 
direct  sunshine  as  mosses  and  ferns.  He  failed  because,  instead 
of  proceeding  step  by  step,  he  made  the  conditions  too  rigorous. 
When  captive,  wild  animals  are  sterile,  though  still  displaying 
sexual  desires ;  it  is  possible,  in  some  cases  at  least,  that  the 
germ-plasm  in  their  germ-cells  is  so  altered  as  to  be  incapable  of 
directing  development. 

157.  We  observed  that  medical  men  are  in  the  habit  of 
declaring  that  parental  diseases  and  intemperance  usually  result 
in  filial  degeneration,  and  we  noted  that  this  inference  could  not 
possibly  be  correct,  for  otherwise  the  human  race  would  have  long 
ago  become  extinct ;  whereas,  on  the  contrary,  it  has  everywhere 
undergone  protective  evolution.  It  is  possible,  nay  probable,  that 
disease  and  intemperance  are  sometimes,  though  rarely — i.e.  under 
exceptional  conditions  or  in  exceptional  germ-cells — causes  of 
variations  ;  but,  in  view  of  their  long-continued  prevalence,  which 
has  made  them  quite  as  '  normal '  a  part  of  the  environment  as  the 
dangers  to  which  other  types  of  animals  and  plants  are  exposed, 
in  view  also  of  the  fact  that  in  every  case  protective  racial  evolution, 
not  deterioration,  has  occurred,  it  is  hard  to  understand  how 
they  can  be  constant  or  even  frequent  causes  of  the  variations 
which  are  seen  in  children  and  adults.  Nevertheless,  suppose  we 

7 


98  VARIABILITY 

admit  for  the  moment  that  the  medical  inference  is  true  for  the 
present  day,  and  that  disease  and  drink  act  on  the  human  race  as 
the  climate  of  India  is  said  to  act  on  recently  imported  European 
dogs.  It  is  not  denied,  indeed  it  is  a  matter  of  common  observation, 
that  diseased  or  drunken  parents  frequently  have  perfectly  normal 
offspring.  Here,  at  once,  we  see  Natural  Selection  at  work  on  the 
germ-cells.  These  normal  individuals,  whose  germ-plasm  was 
insusceptible,  are  those  that  continue  the  race.  If,  then,  the  germ- 
plasm  of  the  race  is  not  now,  after  thousands  of  years  of  selection, 
as  a  general  rule  insusceptible,  it  is  in  process  of  becoming  so. 
Possibly  the  American  maize  mentioned  by  Metzger  furnishes 
another  instance  of  this  kind  of  selection. 

158.  The  conclusion  we  reach,  then,  is  that,  though  variations 
may  result  from  the  direct  action  of  the  environment,  such  varia- 
tions are,  in  effect,  always  injuries,  and  are  of  rare  occurrence  in 
individuals    who    survive    and   have   offspring.     Adaptation    (i.e. 
evolution)  depends  almost  exclusively  on  spontaneous  variations. 
These  do  not  imply  damage  to  the  germ-plasm,  but  are  products 
of  its  vital  activity.      Occurring  in  vast  abundance  all  round  the 
specific  and  parental  means,  they   supply  the   sole  material  for 
Natural  Selection. 

159.  We  conceive  the  germ-plasm ,  then,  as  living  and  active -, 
closely  adjusted  to    its   environment,  growing,    dividing,    varying, 
capable   of  being  destroyed  and  injured,   but  resisting  death  and 
injury,     and    within    limits    capable    of    repairing    damage    and 
returning  to   its   original  state — as   behaving    exactly  as  a  living 
individual  does.     Plenty  of  biologists  think  of  it  as  drifting  like  a 
dead  thing  at  the  mercy  of  circumstances,  incapable  of  making 
vital  reactions,  capable  of  undergoing  all  sorts  of  radical  alterations 
and  yet  of  surviving.     But  never  yet  have  I  met  anyone  holding 
this    opinion   who   was    willing   to   make    a    rigorous   deductive 
inference    of    consequences,  and    explain    how   it    happens    that 
races  exposed  to  unfavourable  conditions  undergo,  not  deteriora- 
tion, but  adaptation.     As  well  might  it  be  maintained  that  if  a 
man  goes  continually  down  hill  he  will  ultimately  arrive  at  the 
top. 

1 60.  The  problem  of  the  causation  of  variations  is,  both 
theoretically  and  practically,  one  of  the  most  important  of  all 
biological  problems.  A  discussion  prolonged  but  singularly  futile, 
and  founded  mainly  on  experiments  and  observations,  innumerable 
but  peculiarly  irrelevant,  has  raged  about  it.  From  such  experi- 
ments as  those  of  Clayton  on  beans,  men  have  inferred  that  all 


THE  CAUSATION  OF  VARIATIONS  99 

variations  are  caused  by  the  direct  action  of  the  environment.  As 
a  fact  it  is  impossible  to  solve  the  problem  experimentally. 
An  experiment  cannot  be  made  unless  the  animal  or  plant 
used  for  the  purpose  is  removed  from  its  normal  environment  to 
one  very  different ;  and  the  question  is,  not  whether  it  is  pos- 
sible to  devise  conditions  in  which  the  germ-plasm,  though  not  de- 
stroyed outright,  is  injured  beyond  recovery,  but  whether,  under 
the  conditions  in  which  species  maintain  their  characters  or  undergo 
adaptive  change,  variations  commonly  arise  through  the  direct 
action  of  the  environment  In  other  words,  the  question  is  whether 
variations  are  normally  spontaneous  or  due  to  enforced  alteration. 
In  the  search  for  experimental  data  and  the  '  obvious  inferences ' 
so  often  drawn  from  them,  the  whole  problem  of  adaptation  has 
been  actually,  though  not  ostensibly,  ignored.  Men  have  failed  to 
make  the  obligatory  deductive  inference  of  consequences  followed 
by  an  appeal  to  reality.  They  have  not  asked  themselves  how  the 
multitudinous  and  delicate  adaptations  and  co-adaptations  of 
animals  and  plants  could  have  arisen  if  species  had  drifted  at  the 
mercy  of  the  environment,  nor  troubled  their  heads  with  such 
notorious  facts  as  that  human  beings  persist  and  for  ages  have 
persisted  in  lands  where  every  individual  is  saturated  with  the 
poisons  of  malaria  or  other  virulent  diseases.  That  is  to  say  they 
have  not  taken  the  whole  of  the  facts  into  consideration.  If  the 
reader's  thinking,  also,  is  not  to  be  mere  guessing,  he  must  follow 
the  procedure  which  has  led  to  the  creation  of  all  science  that  is 
more  than  a  mere  catalogue  of  likenesses  and  differences,1  and,  bear- 
ing in  mind  that  species  become  adapted  to  their  surroundings,  ask 
himself  to  what  the  adaptation  is  due,  to  a  vital  reaction  resulting 
from  the  Natural  Selection  of  favourable  spontaneous  variations, 
or  to  a  helpless  drift  resulting  from  germinal  changes  caused  by 
the  direct  action  of  the  environment.  In  other  words,  he  must  ask 
himself  which  of  these  contradictory  hypotheses  can  be  conceived 
as  being  in  accord  with  the  facts  of  existence. 

161.  Some  biologists  have  argued  that  influences  (e.g.  abundant 
nutriment)  from  the  environment  acting  on  the  germ-plasm  tend 
to  cause  variations  all  round  the  specific  mean.  But  if  the  germ- 
plasm  contained  in  the  germ-cells  of  the  species  is  everywhere 
very  similar — as  it  must  be,  since  the  individuals  of  the  species 
resemble  one  another — then  a  force  acting  on  it,  if  it  causes  any 
change,  must  cause  everywhere  much  the  same  change  and  there- 
fore a  general  drift  in  this  or  that  direction.  It  is  only  when 

^ee  §§  819  et  seq. 


ioo  VARIABILITY 

the  germ-plasm  in  the  different  cells  is  dissimilar  (i.e.  has  varied 
spontaneously)  that  the  changes,  if  any,  can  be  dissimilar.  But, 
if  it  be  admitted  that  germ-cells  vary  spontaneously,  it  is  un- 
necessary to  appeal  to  the  action  of  the  environment!  to  explain 
facts  which  are  already  sufficiently  explained.  In  science  "  neither 
more  nor  more  onerous  causes  are  to  be  assumed  than  are  necessary 
to  account  for  the  phenomena." 

162.  The  apparently  well  authenticated  fact  that  species  (e.g. 
wild  plants)  removed  to  a  new  environment  (e.g.  cultivated  garden) 
tend,  though  healthy  and  prolific,  to  display,  especially  after  the 
lapse  of  several  generations,  greater  variability  than  in  the  ancestral 
habitats,  has  also  been  advanced  in  support  of  the  hypothesis  that 
variations  are  commonly  caused  by  the  direct  action  of  the  en- 
vironment. Here  again  we  are  asked  to  believe  that  an  influence 
(i.e.  the  sum  of  the  new  influences  in  the  new  environment,  which 
presumably  is  much  the  same  for  all  or  nearly  all  the  germ-cells) 
causes  variations  all  round  the  specific  mean.  But  Natural  Selec- 
tion not  only  adapts  species  to  changing  environments  but  keeps 
adapted  species  stable  in  stable  environments.  Speaking  generally, 
natural  environments  are  very  stable — so  stable  that  all  distinct 
species  are  very  old,  and  some  have  persisted  without  appreciable 
change  for  enormous  epochs  of  time.  During  the  entire  historical 
era,  though  natural  varieties  may  have  arisen,  not  a  single  species 
is  known  to  have  altered  appreciably  as  a  whole.  Variability  is 
not  lacking,  since  man  is  able  to  create  varieties  very  swiftly  by 
artificial  selection.  Obviously,  any  considerable  variation  in  a 
species,  already  closely  adapted  by  thousands  of  years  of  selection 
to  its  environment,  is  almost  sure  to  be  disadvantageous.  A 
superior  tendency  to  vary,  itself  a  variation,  is,  therefore,  disadvan- 
tageous, and  is  eliminated  in  an  environment  to  which  the  species 
is  already  well  adapted.  But  it  is  advantageous  in  a  new 
environment  to  which  the  species  must  become  adapted,  and  not 
unfavourable,  or  not  so  unfavourable  in  a  new  environment  (e.g. 
garden)  to  which  the  species  is  adapted,  but  where  the  old  causes 
of  elimination  do  not  act.  In  brief  terms  the  characters  which 
adapt  species  to  their  environments  include  a  right  degree  of 
variability ;  that  is,  the  degree  of  variability  displayed  by  every 
species  is  itself  an  adaptation.  When  monsters,  for  example, 
perish,  it  is  not  only  unfavourable  variations  which  are  eliminated, 
but  also  a  tendency  to  vary  to  an  extent  too  great  to  produce  fitness 
to  the  parental  environment.  It  follows,  then,  that  the  fact  that 
species  tend  to  become  more  variable  in  a  new  environment  is 


VARIABILITY  IS  AN  ADAPTATION  101 

evidence,  not  that  the  germ-plasm  is  directly  affected  by  its 
surroundings,  but  that  Natural  Selection,  which  controls  and 
which  formerly  limited  the  amount  of  variability,  no  longer  does  so 
to  the  same  extent. 

163.  The   foregoing   leads  us  to   a  very   important   problem. 
Though  environments  as  a  whole  are  very  stable,  yet  they  are 
seldom  if  ever  absolutely  stable  in  every  particular  for  prolonged 
periods.     One  or  other  factor  amongst  the  complex  of  which  they 
are  compounded  tends  always  to   be   undergoing  change.     New 
factors  of  elimination  appear,  or  old  factors  become  more  stringent 
or  less  stringent.     Thus,  during  the  last  few  centuries  many  new 
and  fatal  diseases  have  appeared  amongst  the  human  inhabitants 
of  the   Western    Hemisphere ;  while   in   the   Eastern    world   the 
increase  of  population  has  accentuated  the  stringency  of  selection 
by  old-established  diseases  at  the  same  time  that  elimination  by 
war,  famine,  and  wild  beasts  has  diminished.     Species  change  in 
adaptation  to  changing  environments,  and  thus  all  forms  of  life 
known  to  us  have  arisen.     The  fact  that  they  have   undergone 
evolution  is  proof  that  their  environments  have  undergone  change. 
Man,  for  example,  is  not  fitted  for  the  same  environment  as  that 
in  which  his  pre-human  ancestors  existed,  nor  would  the  latter  be 
fitted  for  his  present  surroundings.1     The  evolution  of  a  species 
is  founded  on  the   variations  of  its  individuals.     Were  offspring 
exact  reproductions  of  parents,  the  race  would  persist  only  if  it 
were  well  adapted  to  a  perfectly  stable  environment.     A  right 
degree  of  spontaneous  variability  therefore  is  an  essential  condition 
of  persistence.      Presumably,  therefore,   it  is  an  adaptation — with 
insusceptibility  to  the  direct  action  of  the  environment ',  the  most  useful 
and  important  of  all  adaptations  ;  as  much  an  adaptation  as  hands, 
eyes,  lungs,  or  any  other  of  the  functioning  characters  of  living 
types.     It  is  not,  as  is  often  implied,  a  chance  property  of  germ- 
cells,  comparable,  for  example,  to  the  colour  of  a  dead  leaf.     And, 
if  it  is  an  adaptation,  then,  reasoning  by  analogy,  it  has,  like  all 
other  adaptations,    been    established    and   maintained  by   Nattiral 
Selection. 

164.  We  need  not  attempt  to  discuss  at  length  the  question  as 
to  how  variability  began  in  living  beings.     Like  all  other  problems 
relating  to   the   beginnings    of    life,  its   origins   are   involved    in 
obscurity.     Variations  of  some  sort  must  have  preceded  Natural 
Selection,  if  only  for  a  moment,  for  otherwise  the  latter  could  have 
had  no  material  with  which  to  work.     But,  probably,  even  these 

1  See  §  770. 


102  VARIABILITY 

earliest  variations  were  spontaneous,  for  it  is  at  least  unlikely  that 
the  multiplication  of  the  primitive  living  beings  involved  exact 
quantitative  and  qualitative  division.  Doubtless  early  variations, 
however  caused,  were  seized  upon  by  Natural  Selection,  which,  as 
a  necessary  antecedent  to  all  else,  established  the  insusceptibility 
of  the  germ-plasm  and  regulated  the  tendency  to  vary  in  all 
directions  about  the  specific  mean.  In  other  words,  though 
Natural  Selection  cannot  have  been  the  original  source  of  varia- 
tions, it  has  established  variability  as  an  adaptation  and  ensures 
its  constant  occurrence,  and  in  each  species  has  regulated  the 
amount  of  it  according  to  the  needs  of  the  time.  At  any  rate, 
however  spontaneous  variability  originally  arose,  it  certainly 
exists  and  presents  all  the  signs  of  an  adaptation  controlled  by 
Natural  Selection. 

165.  Striking  evidence  that  spontaneous  variability  is  a 
strictly  regulated  adaptation,  and  that  germinal  insusceptibility  to 
the  direct  action  of  the  environment  is  also  an  adaptation,  is 
furnished  by  four  well-authenticated  facts.  First,  plants  propagated 
asexually  (by  slips,  suckers,  etc.)  vary  very  little  as  long  as  they 
are  so  propagated,  no  matter  how  numerous  the  pseudo-generations, 
nor  how  diverse  the  influences  to  which  they  are  exposed  and  by 
which  they  may  be  modified ;  wherefore  gardeners,  whenever 
possible,  propagate  valuable  varieties  by  means  of  cuttings.1  This 
indicates  that  variations  are,  at  least,  rare  amongst  somatic  cells, 
for,  if  they  were  common,  plants  propagated  asexually  would  be 
changeful.  Second,  offspring  arising  by  seminal  generations  (i.e. 
from  germ-cells)  always  vary  from  their  parents.  This  indicates 
that  variations  occur  normally  within  the  limits  of  the  germ-tract, 
that  is  in  those  lines  of  cells  by  which  the  germ-cells  of  the 
individual  descend  from  the  fertilized  ovum  whence  he  sprang. 
Third,  the  offspring  of  a  plant  reared  from  its  seed  vary  no  more 
and  no  less,  apparently,  when  the  seed  is  gathered  at  the  end  of 
the  first  season,  than  when  it  is  gathered  after  many  seasons  during 
the  course  of  which  the  plant  has  been  propagated  asexually.  In 
other  words,  the  lengthening  of  the  germ-tract  by  any  number  of 
pseudo-generations  (i.e.  slips  and  suckers)  does  not  appear  to 
increase  the  number  and  magnitude  of  variations.  This  indicates 
that  variations  do  not  arise  all  along  the  germ-tract,  but  once  for 
all  in  some  particular  part  of  it ;  for,  if  they  arose  all  along  the 
tract,  the  lengthening  of  it  would  tend  to  influence  their  number 
and  magnitude.  Fourth,  *  identical '  twins,  which  originate  from  a 

1See§  183. 


THE  PLACE  OF  ORIGIN  OF  VARIATIONS  103 

single  fertilized  ovum,  are  closely  alike,  while  those  which  arise 
from  different  ova  (even  in  the  case  of  peas  in  the  same  pod) 
differ  as  much,  or  almost  as  much,  as  offspring  born  at  suc- 
cessive births  or  seasons.  This  indicates  that  the  part  of  the 
germ-tract  at  which  variations  normally  arise  is  the  last,  or  one  of 
the  last,  cell-divisions  that  precede  the  ripening  of  the  germ-cells ; 
for  if  variations  occurred  earlier,  not  only  identical  twins,  but  whole 
batches  of  offspring  would  tend  to  be  identical,  especially  when 
the  reproduction  was  parthenogenetic. 

1 66.  The    following    diagram    may    help    to    elucidate    the 
argument. 

A 


MAMlMMMMM/t 


-z 


167.  Suppose  A  is  a  fertilized  ovum  from  which  the  cells  of  the 
germ-tract   B,  C,  D  .  .  .     Y,  Z,  are  derived.     Z   represents   the 
descendant  germs.     Granting  that  variations  arise  at  a  particular 
point  in  the  tract,  then,  if  they  arise  at  A,  B1  will  differ  from  B2, 
as  will  their  descendants  ;  but  all  the  descendants  of  B1  will  be 
alike,  as  will  be  those  of  B2.     If  variations  arise  at  B,  there  will 
be  four  batches  of  identical  descendants.     If  at  C,  eight.     And  so 
on.     But  if  the  point  at  which  variations  arise  is  at  Y,  there  will 
be  no  identical  germs,  except  (especially  in  the  case  of  complex 
organisms)  as  a  very  unlikely  coincidence.     On  the  other  hand 
if  variations  arose  all  along  the  germ-tract,  then,  though  all  the 
germs  would  tend  to  differ,  the  lengthening  of  the  germ  tracts,  as 
by  pseudo-generations,  would  tend  to  increase  variability,  which, 
as  we  see,  does  not  happen. 

1 68.  Now,  the   evidence   is   that  all  these   laws  (laws   in  the 
scientific  sense  of  uniformities  in  the  sequences  of  events),  unlike 
the  laws  of  physics,  have  exceptions.     Thus  somatic  cells  some- 
times vary  spontaneously,  as  when  a  branch  bearing  nectarines 
appears  on  a  peach  tree.      Again,  when  a  cancer  appears  in  the 
tissues  of  a  man,   the  variation  seems  frequently  to  be  caused, 


104  VARIABILITY 

in  some  measure  at  least,  by  the  environment,  for  such  tumours 
are  seen,  especially  in  irritated  tissues.  Germ-cells,  or  cells  of  the 
germ-tract,  appear  also  to  be  affected  sometimes  by  the  direct 
action  of  the  environment,  as  in  the  case  of  Clayton's  beans  and 
European  dogs  in  India.  But,  as  we  have  insisted,  evolution  is 
never  perfect ;  the  '  laws '  created  by  it  have  ever  exceptions ; 
for  it  is  only  by  eliminating  the  exceptions  that  nature  creates 
and  maintains  uniformities  amongst  living  beings.  The  fact  that 
these  exceptions  occur  is  in  accordance,  therefore,  with  all  we 
know  concerning  the  adaptations  of  living  beings. 

169.  The  advantage  of  the  practical  limitation  of  the  occur- 
rence  of  variations    to   a  particular    part   of  the    germ-tract   is 
obvious.     If  variations  occurred  amongst  somatic  cells,  they  would 
tend  to  ruin  co-adaptation  among  the  cells  that  varied  (and  their 
descendants)  and  the  other  somatic  cells  (and  their  descendants) — a 
co-adaptation  which  has  been  achieved  only  by  prolonged  evolution. 
A  cancer  which  results,  seemingly,  from  a  variation  in  a  somatic  cell 
(a  variation,  like  other  variations,  inheritable  by  the  descendants  of 
the  cell)  is  an  example.    Moreover,  such  variations,  even  if  favourable 
to  the  individual,  would  be  useless  to  the  species,  for,  save  in  the 
event  of  the  Lamarckian  hypothesis  being  true,  they  would  not  be 
reproduced  by  the  offspring  of  the  individual.     On  the  other  hand, 
germinal  variations,  while  affording  the  necessary  materials  for 
Natural  Selection,  do  not  affect  the  well-being  of  the  community  of 
which  the  germs  are  members,  for  here  the  germs  have  no  functions. 
Again,  if  variations  occurred  all  along  the  germ-tract,  they  would 
accumulate,  and   offspring  would  tend  to  vary,  not  in  the  right 
degree,  but  in  proportion  to  the  length  of  the  tract  and  in  pro- 
portion to  the  duration  of  time  that  clasped  between  the  fertilizing 
of  the  ovum  from  which  the  parent  arises  and  the  production  of 
his  offspring  ;  that  is,  the  offspring  earliest  produced  would  tend 
to  vary  less  than  those  produced  later.     Lastly,  if   the  point  at 
which  variations  normally  occur  were  situated,  not  at  the  end  of 
the  germ-tract,  but  earlier  in  it,  then,  in  proportion  as  the  point 
was  near  the  beginning  and  distant   from  the  end  of  the  tract, 
larger  and  larger  batches  of  germ-cells  would,  as  I  say,  tend  to  be 
identical.     By  limiting  normal  variability  to  the  end  of  the  germ- 
tract,  nature  ensures,  on  the  one  hand,  that  all  germ-cells  shall  vary 
from  one  another,  and,  on  the  other,  secures  control  over  variations, 
which  are  then  soonest  put  to  the  test  of  fitness  to  the  environment. 

170.  It  may  be  thought  that  I  have  carried  deductive  thinking 
too  far   in  the  preceding  paragraphs.     But  the  facts  on  which  I 


THE  ORIGIN  OF  VARIATIONS  105 

have  relied  are,  I  believe,  not  disputed,  and  I  find  it  hard — as  I 
think  the  reader  will — to  conceive  interpretations  of  them  other 
than  those  I  have  suggested.  Germinal  insusceptibility  to  the 
direct  action  of  the  environment  and  a  right  degree  of  variability 
are  just  as  much  adaptations,  essential  to  the  survival  of  the 
species,  as  any  of  the  structures  and  functions  of  the  individual. 
Presumably,  therefore,  they  are  just  as  much  under  the  control  of 
Natural  Selection.  The  limitation  of  variations  to  a  particular 
part  of  the  germ-tract  would  not  appear  a  task  more  difficult  for 
Natural  Selection  than  the  evolution  of  such  wonderfully  complex 
and  delicate  structures  as  the  eye  and  ear. 

171.  We  are  often  told  that  the  'cause'  or  'origin'  of 
spontaneous  variations  is  unknown.  If  it  be  meant  that  the 
molecular  processes  in  the  germ-plasm  which  result  in  variations 
are  unknown,  the  statement  is  true.  In  that  sense  we  do  not 
know  the  cause  of  any  kind  of  variations,  not  even  of  those  which 
clearly  result  from  the  direct  action  of  the  environment.  But  in 
another  sense  it  is  untrue — as  untrue  as  if,  knowing  that  a  certain 
variation  was  caused  by  a  certain  influence  in  the  environment, 
we  declared  that  the  origin  of  it  was  unknown.  The  fertilized 
ovum  has  two  classes  of  cell-descendants,  both  of  which  vary 
spontaneously,  the  somatic  cells  and  the  germ-cells.  The  former 
do  not  vary  away  from  type  ;  nevertheless  they  vary  in  a  regular 
manner  from  the  fertilized  ovum  and  amongst  themselves,  some 
becoming  skin-cells,  others  muscle-cells,  and  so  on.  We  suppose 
we  know  something  very  definite  about  the  origin  of  these  altera- 
tions when  we  declare  that  they  result  from  evolution  and  are 
under  the  control  of  Natural  Selection.  Precisely  the  same 
declaration  may  be  made  about  the  less  regular  but  equally 
constant  variations  of  germ-cells.  A  germ-cell  which  has  not 
varied,  has  varied  in  that  it  has  departed  from  a  type  which,  in 
effect,  always  varies.  People  who  insist  that  we  do  not  know  the 
cause  of  variations,  and  that  the  word  '  spontaneous '  is  nothing 
other  than  a  cloak  for  ignorance,  are  unaware  of  the  sense  in  which 
that  word  is  used,  or  they  have  not  considered  the  evidence, 
or  they  are  the  kind  of  people  who  insist  on  experimental 
evidence  and  are  unaware  of  the  impossibility  of  devising  experi- 
ments which  would  furnish  it. 

172.  We  reach,  then,  three  principal  laws  of  heredity — three 
summaries  of  facts,  (a)  The  germ-plasm  is  highly  insusceptible 
to  the  direct  action  of  the  environment;  (b)  the  vast  majority 
of  variations — all  those  on  which  evolution  is  founded — are 


io6  VARIABILITY 

spontaneous  ;  (c)  the  development  of  the  multicellular  organism 
is  a  recapitulation — however  inaccurate  and  incomplete — of  the 
evolution  of  the  race.  All  these  three  characters,  insusceptibility, 
regulated  variability,  and  recapitulation  are  due  to  Natural  Selec- 
tion— or  miracle.  If  the  reader,  bearing  in  mind  the  whole  of 
the  evidence,  not  merely  isolated  items,  will  think  the  matter  out 
carefully,  I  believe  he  will  find  there  is  no  escape  from  the 
conclusion  that  all  species  must  possess  the  first  two  characters  or 
perish,  and  that  the  third  also  must  be  present  in  all  multicellular 
types.  He  will  be  driven  to  conclude,  also,  that  they  are  not 
mere  chance  characters,  but  products  of  evolution  which  Natural 
Selection  wonderfully  and  beautifully  regulates,  which  form  the 
foundation  of  all  other  adaptations,  and  are,  therefore,  the  most 
universal  and  important  of  all  of  them.  The  non-recognition  of 
them  as  adaptations,  necessary  and  inevitable  adaptations,  which 
underlies  so  much  of  modern  thought  and  research,  attests  better 
than  anything  else  the  failure,  fatal  to  a  right  comprehension  of 
life,  to  realize  that  all  normal  living  beings  are,  speaking  practically, 
nothing  other  than  bundles  of  adaptations. 


CHAPTER   VI 
RETROGRESSION 

Evidence  of  retrogression — Theories  of  retrogression — Conditions  under  which 
retrogression  occurs — The  speed  of  retrogression — The  difficulty  of  recognizing 
the  identity  of  retrogression  and  reversion — Latent  characters — The  retrogression 
of  variations — The  magnitude  of  the  part  played  by  retrogression — Retrogres- 
sion in  the  developing  individual — Reversed  selection — '  Ancestral  units  ' — The 
'  contributions  of  ancestors  ' — The  law  of  ancestral  inheritance — Biometry. 

X73-  ^  I  CHOUGH,  speaking  practically,  the  doctrine  of  evolu- 
tion is  accepted  by  all  who  know  the  facts,  that  of 
"^  evolution  by  Natural  Selection  has  not  as  yet  received 
such  general  assent.  A  vague  terminology,  and  a  belief  that 
nutritional  characters  are  peculiarly  '  innate '  and  that  '  acquire- 
ments '  are  not  products  of  evolution,  combined  with  the  obvious- 
ness of  the  Lamarckian  doctrine  and  the  difficulty  of  explaining 
co-adaptation  when  the  magnitude  of  *  use-acquirements '  is  not 
realized,  still  inclines  some  biologists  to  a  faith  that  the '  inheritance ' 
of  acquirements  accounts,  in  part  at  least,  for  evolution.  Others, 
because  they  are  unable  to  perceive  the  utility  of  some  charac- 
ters in  types  so  far  removed  from  the  human  that  our  know- 
ledge of  their  dangers  and  activities  is  very  imperfect,  have 
supposed  that  such  characters  have  no  utility,  that  they  are  not 
adaptations,  and,  therefore,  that  they  do  not  owe  their  evolution  to 
Natural  Selection,  which,  consequently,  does  not  play  an  exclusive, 
but,  on  the  contrary,  only  a  more  or  less  minor  part  in  the  causa- 
tion of  specific  change.1  Yet  others,  because  a  few  species,  when 
the  environment  is  changed,  display  quite  suddenly  considerable 
adaptive  alterations,  pin  their  faith  to  that  circumlocution  for 
miracle,  an  '  adaptive  growth-force.' 2 

174.  But  perhaps  the  main  reason  against  a  full  acceptance  of 
the  Darwinian  doctrine — that,  at  any  rate,  which  has  influenced 
most  biologists  in  the  past — has  been  drawn  from  the  retrogression 
of  useless  parts  and  organs.  In  all  complex  types  occur  traces  of 
organs  which  formerly  were  useful  and  of  considerable  relative 

1  See  §§  306,  649.  2  See  §  92. 

107 


io8  RETROGRESSION 

magnitude,  but  which  are  now  shrunken  to  mere  vestiges.  Thus 
in  the  ostrich  the  wings  are  no  longer  capable  of  sustaining  the 
animal  in  flight.  In  the  apteryx  they  are  quite  functionless  and 
so  rudimentary  as  to  be  hidden  in  the  feathers  of  the  body.  In 
the  extinct  dinornis  they  had,  apparently,  disappeared  altogether. 
In  most  snakes  no  traces  remain  of  limbs,  but  in  the  python  the 
hinder  pair  are  still  represented  by  vestiges.  In  some  species  of 
whales,  also,  the  hinder  pair  have  disappeared  ;  in  others  the  small 
remains  of  them  are  buried  in  the  body.  Man  has  numerous 
vestiges  of  structures  which  formerly  were  functional,  for  example, 
the  hairy  covering  of  his  body. 

175.  Lamarckians  have  attributed  the  retrogression  of  useless 
parts  to  the  transmitted  effects  of  disuse.     But  man,  for  example, 
never  'used'  the  hair  of  his  head  more  than  that  of  his  body; 
nevertheless  the  former  persists,  whereas  the  latter  has  become 
vestigial.     However,  it  is  unnecessary  to  discuss  the  Lamarckian 
doctrine  here.      The  reasons  which  caused  us  to  reject  it  as  an 
interpretation  of  progression  are  valid  against  it  as  an  interpreta- 
tion of  retrogression. 

176.  At  first  Darwinians  attributed  retrogression  to  reversed 
selection,  "  the  selection  which  effects  not  increase  of  an  organ,  but 
decrease  of  it."     They  argued  that  useless  structures  are  worse 
than  useless,  they  are  burdensome ;  therefore  nature  secures  their 
disappearance  by  eliminating  the  most  burdened  individuals.     But 
the  evidence  is  very  ample  that  selection  is  a  cause  of  racial  change 
only  when  it  is  stringent,  and  a  hairy  man  is  not  really  burdened 
to  an  appreciable  extent  as  compared  with  less  hairy  men  ;  at  any 
rate,  not  to  such  an  extent  as  to  diminish  his  chances  of  survival. 
Again,  pythons  and  whales,  which  have  vestiges  of  hind  limbs, 
and  the  apteryx,  which  has  vestiges  of  fore  limbs,  are  hardly  at  a 
disadvantage  as  compared  to  species  in  which  retrogression  has 
been  complete.     A  fortiori,  individuals  of  the  same  species  which 
have  vestiges   a   trifle   smaller  than  their  fellows,  have   on  that 
account  no  greater  chance  of  survival.     Osborn  was  very  right 
when    he    declared    in   reference   to   this  question,    "  If  acquired 
variations  are  transmitted,  there  is   some  unknown    principle   in 
heredity  ;  if  they  are  not  transmitted,  there  must  be  some  unknown 
factor  in  evolution." 

177.  Next,  Darwinians  argued  that  the  struggle  for  nutriment 
is  very  severe,  and  that  useless  structures  absorbed  nutriment  and 
so  increased  elimination.      But   useless    structures,   being   inert, 
especially  when  composed  of   a  stable  tissue   like   bone,  absorb 


EXPLANATIONS  OF  RETROGRESSION  109 

very  little  nutriment.  Moreover,  it  is  not  the  total  amount  of 
nutriment  absorbed  by  the  vestiges  that  is  in  question,  but  only 
the  difference  in  the  amounts  consumed  in  the  vestigial  struc- 
tures of  the  individual  that  survives  and  the  one  that  perishes. 
It  requires  faith  of  a  really  magnificent  order  to  believe,  for 
instance,  that  the  daily  addition  or  subtraction  of  a  grain  or  less 
of  nutriment  can  have  influenced  the  survival  rate  of  the  Greenland 
whale. 

178.  Next,  it  was  asserted  that  the  parts  of  the  individual 
struggle  amongst  themselves  for   nutriment,  and  the  parts  most 
used  being  most  stimulated  received  more  than  their  share,  and  as 
a  consequence  flourish  at  the  expense  of  the  others,  which  atrophy. 
This  hypothesis,  however,  is  merely  a  particular  application  of  the 
Lamarckian  doctrine. 

179.  In  his  hypothesis  of  Germinal  Selection,  Weismann  has 
very  ingeniously  transferred  the  struggle  for  nutriment  from  the 
individual  to  the  germ-plasm.     He  supposes  that  the  parts  of  the 
individual  are  represented  in  the  germ-plasm  by  'determinants/ 
which  multiply  like  cells,   so  that  descendant  determinants  are 
present  in  descendant  germ-cells.     A  weak  determinant  produces 
a  minus  (retrogressive)  variation.     Being  weak,  it  is  vanquished 
in  the  struggle  for  food  by  stonger  determinants,  and  so  grows 
weaker,  and  transmits  its  weakness  to  offspring  and  descendants. 
If  the  part  it  represents  be  useful,  the  individual  who   has  the 
minus  variation  tends  to  perish  through  Natural  Selection,   the 
race  being  continued  by  the  individuals  in  which  the  determinant 
is  stronger,  and  the  part  therefore  better   developed.      If  it   is 
useless,  he  tends  to  survive,  and  the  process  of  weakening  con- 
tinues with  added  force  in  successive  generations,  till  at  length  the 
determinant  perishes  and  the  part  disappears.    In  brief,  Weismana 
supposes  that  the  determinants  of  useless  parts  are  not  helped  Ly 
selection,  whereas  the  determinants  of  useful  parts  are  helped  by 
it ;  and,  therefore,  that  the  former  tend  to  be  vanquished  by  the 
latter  in  the  struggle  for  nutriment. 

1 80.  Weismann's   hypothesis    consists   of    two    portions — an 
induction  and  a  deduction,  the  latter  being  an  expansion  of  the 
former.       (a)    Mere   cessation  of  selection  is  followed    by  retro- 
gression, (b)  because  the  determinants  of  useless  parts  tend  to  be 
starved.     It  is  possible  to  agree  with  the  first,  which  is  founded 
on  observed  facts  and   can   be  tested,  without  assenting  to  the 
second,  which  is  neither  founded  on  observed  facts  nor  has  been 
tested.     According  to  this  hypothesis,  lack  of  nutriment  is  a  cause 


no  RETROGRESSION 

of  retrogressive  variations,  and  abundance  of  nutriment  a  cause  of 
progressive  variations.  In  other  words,  it  is  supposed  that  varia- 
tions are  not  always  spontaneous,  but  are,  very  often  at  least, 
caused  by  the  direct  action  of  the  environment — a  notion  which, 
in  the  main,  Weismann  himself  has  strenuously  controverted.  But, 
if  determinants — supposing  they  exist  as  discrete  elements  in  the 
germ-plasm — compete  for  nourishment,  the  competition  should  be 
sharpest  and  most  destructive  when  nutriment  is  least  abundant, 
and  non-existent  when  it  is  superabundant.  In  that  case  species 
which  possess  very  abundant  nutritive  supplies  (e.g.  internal 
parasites,  unicellular  and  multicellular)  should  display  little  or  no 
retrogression,  whereas  species,  the  nutritive  supply  of  which  is  so 
small  that  they  are  engaged  in  an  endless  struggle  for  it,  in  which 
many  perish  (e.g.  most,  if  not  all  fishes,  reptiles,  birds,  and 
mammals)  should  display  little  progression  and  much  retro- 
gression. The  exact  opposite  is  the  truth.  The  microbes  of 
syphilis  remain  microscopical  though  their  determinants  have 
absolutely  soaked  in  nutriment  for  thousands  of  years,  and  of  all 
known  organisms  the  multicellular  pasasites  display  the  greatest 
amount  of  retrogression.  Some  of  them  are  little  more  than 
egg-cases.  Fishes,  reptiles,  birds,  and  mammals,  on  the  other 
hand,  are  typical  examples  of  progression.  In  neither  case  has 
the  inevitable  drift  ensued  which  would  necessarily  have  followed 
were  this  hypothesis  true — a  drift  which  would  tend  to  abolish 
Natural  Selection,  and  therefore  adaptation. 

1 8 1.  Of  all  the  splendid  services  rendered  by  Weismann  to 
biology  none  is  more  valuable  than  his  long  and  successful 
struggle  to  overthrow  the  Lamarckian  doctrine.  Since  merely 
useless  parts  tend  to  become  vestigial  and  disappear,  his  success 
involves  the  corollary  that  simple  cessation  of  selection  (i.e.  cessa- 
tion of  utility),  which  may,  or  may  not,  imply  cessation  of  use,  is 
followed  by  retrogression,  which  in  turn  implies  that  to  prevent 
retrogression  a  certain  stringency  of  selection  is  necessary,  while 
to  cause  progression  a  still  greater  degree  of  stringency  is  required. 
The  retrogression  of  old-established  parts  is  very  slow.  Thus  the 
great  changes  in  whales  and  snakes  since  their  limbs  began  to 
retrogress  indicates  an  enormous  lapse  of  time.  Doubtless,  also, 
geological  epochs  must  pass  before  Greenland  whales  and  pythons 
lose  even  the  small  vestiges  of  hind  limbs  which  they  still  possess. 
On  the  other  hand,  newly  acquired  characters  tend  to  disappear 
very  rapidly  on  cessation  of  selection,  as  may  be  noted  in  the 
case  of  the  special  traits  of  our  prize  breeds.  Absolutely  new 


THE  CAUSE  OF  RETROGRESSION  in 

characters  (i.e.  variations)  tend  to  disappear  in  the  next  generation 
(e.g.  birth-marks,  moles,  etc.).1 

182.  Since,  then,  the  tendency  to  retrogression  is  greater  in  the 
case  of  new  characters  than  of  old-established  traits,  the  stringency 
of  selection  by  which  the  former  are  maintained,  or  by  which  fresh 
progression   may  be  caused  in  them,  is  proportionately  intense.2 
In  other  words,  offspring  frequently  display  progressive  variations 
in  the  case  of  old-established  characters,  whereas  in  the  case  of 
new  traits  the  great  mass  of  variations  is  retrogressive.     Thus,  if 
we  try  to  improve  the  long-established  characters  of  a  compara- 
tively old  race,  for  example  ordinary  horses,  our  task  is  much  less 
difficult   than  if  we  operate  on  the  new  characters  which  have 
recently  been  evolved  under  stringent  selection,  for  example  the 
special  traits  of  race-horses.3     In  the  latter  case  the  tendency  to 
retrogression  is  sometimes  so  great  that  our  utmost  efforts  may  do 
no  more  than   prevent  retrogression.     In  other  words,  stringent 
selection  no  longer  causes  progression. 

183.  Since  even  old-established  characters  retrogress  on  cessa- 
tion of  selection,   it  follows  that  the  frequency,  or  the  magnitude, 
or  both?  of  retrogressive  variations  tends  to  be  greater  than  that  of 
progressive  variations,  and  that  the  difference  is  most  considerable 
in  the  case  of  newly  evolved  characters.     The  fact  that  retrogres- 
sive variations  tend  to  exceed  progressive  variations  in  magnitude 
is  well  shown  by  the  fact  that  while  many  generations  of  selection 
may  be  needed  to  evolve  a  prize  breed,  the  offspring  of  a  pure-bred 
prize  pair  may  in  a  single  generation  display  a  loss  of  the  special 
characters  of  the  parents  and  revert  to  the  ancestral  type.     This 
is  not  uncommon  in  the  case  of  prize  animals,  but  it  is  even  more 

1  Certain    variations    tend,    apparently,    to    possess    a    greater    degree    of 
stability  than  others.     We  shall   deal  with  them  when  we  discuss  Mendelism 
and  the    now  popular  Mutation  theory  of  evolution.     See  chapters  vii.,  viii., 
and  ix. 

2  Some  Mutationists  maintain  that  antiquity  (i.e.  long-continued  selection) 
has  nothing  to  do  with  the  stability  of  characters.     They  insist  that  all  true 
variations    are    absolutely    permanent    from    the    first ;     whereas    '  fluctuating 
variations  '  depend,  not  on  change  in  the  hereditary  tendencies,  but  on  differences 
of  nutrition  and  the  like — on  differences  in  stimuli.     According  to  them  evolution 
is  founded  entirely  on  the  former  class  of  variations.     We  shall  consider  this  view 
also  later. 

3  "  Two  years  ago  thirty-two  yearlings  were  sold  for  51,250  guineas.     These 
thirty-two  yearlings  are  represented  by  two  winners  of  five  races,  Florio  Rubatino 
and  La  Reine,  who  have  contributed  £2000  to  the  total  cost ;  and  there  is  not,  so 
far  as  can  be  known,  a  single  one  of  the  thirty  with  any  prospect  of  making  a  race- 
horse."    (Quoted  from  the  Times,  December  27th,  1897,  by  Sir  Walter  Gilbey, 
Race-horses,  p.  6.) 


1 1 2  RETROGRESSION 

common  with  cultivated  plants.1  Amongst  the  latter,  owing  to 
the  fact  that  offspring  are  more  numerous,  especially  when  it  is 
possible  to  propagate  a  favourable  individual  by  means  of  slips 
from  which  seed  may  be  obtained,  selection  has  been  more  stringent 
and  progression  correspondingly  rapid. 

184.  Now  a  character  (e.g.  eye,  limb,  digestive  system)  which 
is  old-established  is  one  the  usefulness  of  which  has  been  tested  by 
thousands  of  generations  of  continued  selection.  The  permanent 
usefulness  of  more  recently  evolved  characters  (e.g.  special  features 
of  prize-breeds)  has  been  less  thoroughly  tested.  They  have 
favoured  survival,  but  have  arisen  under  conditions  which,  speaking 
comparatively,  may  be  only  temporary.  Absolutely  new  charac- 
ters (i.e.  variations)  have  not  been  tested  at  all,  or  have  been 
tested  for  one  life  only.  The  fact  that  characters  retrogress  with 
a  speed  which  is  inversely  proportionate  to  the  length  of  time 
during  which  their  usefulness  has  been  proved  at  once  raises  a 
suspicion  that  we  are  on  the  track  of  a  very  beautiful  and  very 

1  "  If  a  considerable  number  of  improved  cattle,  sheep,  or  other  animals  of 
the  same  race  were  allowed  to  breed  freely  together,  with  no  selection,  but  with  no 
change  in  their  conditions  of  life,  there  can  be  no  doubt  that  after  a  score  or  a 
hundred  generations  they  would  be  very  far  from  excellent  of  their  kind " 
(Darwin,  A nimals  and  Plants,  vol.  ii.  p.  265).  "  When  selection  is  suspended,  rapid 
deterioration  (from  the  fancier's  standpoint)  is  the  inevitable  result.  If,  e.g.,  a 
number  of  pigeons,  good  specimens  of  a  distinct  breed,  are  isolated  and  left  un- 
molested for  a  few  years,  they  rapidly  degenerate,  i.e.  they  lose  their  show  points 
(be  they  beaks,  frills,  ruffs,  or  metallic  tints)  and  reassume  the  more  fixed  char- 
acters "  (Ewart,  Presidential  Address  to  Zoological  Section  of  the  British  Association, 
1901).  In  1810-14  Lady  Monk  and  Lord  Gambier  collected  some  plants  of  the 
wild  heart's -ease  and  so  began  the  cultivation  of  the  modern  pansy.  Twenty  years 
after,  "  a  book  entirely  devoted  to  this  flower  was  published,  and  400  named 
varieties  were  on  sale  "  (Animals  and  Plants,  vol.  i.  p.  392).  Half  a  century  later 
Darwin  wrote,  "  Cultivators  speak  of  this  or  that  kind  as  being]  remarkably  con- 
stant and  true  ;  by  this  they  do  not  mean,  as  in  other  cases,  that  the  kind  transmits 
its  characters  by  seed,  but  that  the  individual  plant  does  not  change  much  under 
culture.  The  principle  of  inheritance,  however,  does  hold  good  to  a  certain  extent, 
even  with  fleeting  varieties  of  the  Heartsease,  for  to  gain  good  sorts  it  is  indis- 
pensable to  sow  the  seeds  of  good  sorts.  Nevertheless  in  almost  every  large 
seed-bed  a  few  almost  wild  seedlings  will  appear  through  reversion  "  (op.  cit.t 
p.  393).  At  the  present  time  the  seed  of  the  pansy  "  is  of  such  a  quality  and  is 
saved  in  so  many  distinct  colours  that  for  all  ordinary  purposes  the  trouble  of 
striking  cuttings  and  keeping  stocks  in  pots  all  the  winter  through  is  mere  waste 
of  time  and  pot  room"  (The  Culture  of  Vegetables  and  Flowers  from  Seeds  and 
Roots,  issued  by  Messrs  Sutton  &  Co.,  p.  195).  Messrs  Sutton  give  examples 
of  flowers  the  varieties  of  which  have  been  recently  fixed  by  selection  carried 
through  many  generations.  Indeed,  any  number  of  similar  examples  might  be 
given.  Mendelian  experimenters,  however,  explain  the  stability  of  old-established 
characters  otherwise  than  by  continued  selection.  We  shall  discuss  their  hypo- 
thesis presently. 


LATENCY  AND  RETROGRESSION  113 

important  adaptation.  But  before  discussing  this  matter  it  will 
be  well  to  inquire  more  closely  into  the  exact  nature  of  progressive 
and  retrogressive  variations  on  which  all  racial  change  depends. 

185.  We  have  seen  that,  since  the  child  recapitulates,  with  varia- 
tions, the  development  of  the  parent,  he  must  necessarily  recapitu- 
late, with  inaccuracies,  with  additions  and  subtractions,  the  life- 
history  of  the  race.    Whence  it  follows  that  a  progressive  variation 
implies  a  complete  recapitulation  (as  regards  the  character  affected) 
of  the  life-history  as  presented  by  the  parent,  plus  an  addition  ; 
whereas  a  retrogressive  variation  implies  an  incomplete  recapitulation 
of  the  parental  development,  and  therefore  a  reversion  to  the  stage  of 
development  reached  by  some  progenitor  more  remote  than  the 
parent.    There  is  really  no  escape  from  these  conclusions ;  for  grant- 
ing the  undisputed  fact  that  the  child  recapitulates  the  development 
of  the  parent,  other  conclusions  are  actually,  literally,  unthinkable. 

1 86.  The  reader,  however,  must  be  very  careful  not  to  confuse 
latency  with  retrogression.     Latency  implies,  not   the   loss   of  a 
capacity  to  develop  in  this  or  that  direction,  but  only  its  inactivity. 
We  shall  see  later  1  that  it  occurs  when  two  rival  hereditary  tend- 
encies are   present  in   the  germ-plasm,    one   of  which   becomes 
dormant  while  the  other  directs  the  development  of  the  individual. 
Thus    colour-blindness    and    haemophilia,    which   are   commonly 
restricted  to  males,  tend  to    be  transmitted  in  a  latent  condition 
through   daughters   to    grandsons.      All   the   sexual    characters, 
primary  and  secondary,  are  latent  in  individuals  of  the  opposite 
sex.     Thus  the  daughters  of  heavily  bearded  men  tend  to  have 
heavily  bearded  sons.    Male  aphides  are  absent  during  the  summer 
months,  and  reproduction,  therefore,  is  parthenogenetic,  but  at  the 
end  of  the  warm  season  males  are  produced,  which  fertilize  the 
winter  eggs.    Amongst  honey  bees  also  the  reproduction  of  drones 
is  parthenogenetic.      Male  characters,  therefore,  are  latent  in  the 
germ-plasm  of  the  females.   "  It  is  well  known  that  a  large  number 
of  female   birds,   such   as    fowls,   various   pheasants,   partridges, 
pea-hens,  ducks,  etc.,  when  old  or  diseased  or  when  operated  on, 
assume  many  or   all  of  the  secondary  male  characters  of  their 
species.     In  the  case  of  the  hen  pheasant  this  has  been  observed 
to  occur  far  more   frequently  during  certain  years   than  during 
others.     A  duck  ten  years  old  has  been  known  to  assume  both  the 
perfect  winter  and  summer  plumage  of  the  drake.    Waterton  gives 
a  curious  case  of  a  hen  which  had  ceased  laying,  and  had  assumed 
the  plumage,  voice,  spurs,  and  warlike  disposition  of  the  cock  ; 

1  See  chapter  vii. 
8 


114  RETROGRESSION 

when  opposed  to  an  enemy,  she  would  erect  her  hackles  and  show 
fight.  Thus  every  character,  even  to  the  instinct  and  manner  of 
fighting,  must  have  lain  dormant  in  this  hen  as  long  as  her  ovaria 
continued  to  act.  The  females  of  two  kinds  of  deer,  when  old, 
have  been  known  to  acquire  horns  ;  and  as  Hunter  has  remarked, 
we  see  something  of  an  analogous  nature  in  the  human  species."  1 
C.  E.  Walker  injected  an  emulsion  of  testes  into  hens,  thus  supply- 
ing the  necessary  stimuli,  and  caused  them  to  develop  the  combs, 
wattles,  and  warlike  disposition  of  cocks.2  Professor  Giard,  Geoffrey 
Smith  and  others  have  shown  that  when  the  testes  of  crabs  are 
destroyed  by  parasites  (Rhizocephala)  the  males  may  develop  all 
the  characters  of  females,  including  ovaries.  In  some  cases  the 
animal  becomes  a  perfect  hermaphrodite.3  Mr  J.  H.  Orton  has  de- 
monstrated that  the  molluscs  Crepidula  fornicata  and  Calyptrcea 
chinensis  are  males  at  first  but  become  females  later.4 

187.  In  addition  to  the  temporary  latency  typically  seen  in  the 
case  of  the  sexual  characters,  there   is   a   more  permanent  form. 
"  Besides  visible  changes  which  it  [the  germ-cell]  undergoes,  we 
must  believe  that  it  is  crowded  with  invisible  characters  proper  to 
both  sexes,  to  both  the  right  and  the  left  sides  of  the  body,  and  to 
a  long  line  of  male  and  female  ancestors  separated  by  hundreds 
and  even  thousands  of  generations  from  the  present  time  ;  and  these 
characters,  like  those  written  on  paper  in  invisible  ink,  lie  ready  to 
be  evolved  whenever  the  organism  is  disturbed  by  certain  known 
or     unknown     conditions."5      Thus      individuals     derived     from 
domesticated    breeds   of  pigeons    or    fowls   may   reproduce   the 
characters  of  extremely  remote  wild  ancestors.     In  cross-breeding 
between  domesticated  varieties  the  re-appearance  of  hitherto  latent 
ancestral  characters  is  so  common  that  Darwin  declared  "  we  must 
conclude  that  a  tendency  to  this  peculiar  form  of  transmission  is 
an  integral  part  of  the  general  law  of  inheritance."6 

1 88.  There  is  a  good  deal  of  evidence  that  latency  is  influenced 
directly,  in  a  measure  at  least,  by  the  environment.     Thus  Ewart 
rendered  latent  at  will  the  male  or  female  characters  of  rabbits. 
Amongst  bees  the  female   characters   develop   fully  only  under 
certain  conditions  of  environment   in  which,  apparently,  nutriment 

1  Animals  and  Plants,  vol.  ii.  p.  26. 

2  The  Influence  of  the  Testes  upon  the  Secondary  Sexual  Characters  of  Fowls,  1908. 

3  Fauna   und   Flora   des   Golfes  von   Neapel,  Monograph,   29 ;    Rhizocephala, 
Geoffrey  Smith,  Berlin,  1906. 

4  Proc.  Roy.  Soc.,  B.,  vol.  Ixxxi.  pp.  68-84. 
6  Animals  and  Plants,  vol.  ii.  pp.  35-6. 

6  Loc.  cit.,  vol.  ii.  p.  31. 


LATENCY  AND  RETROGRESSION  115 

plays  the  chief  part.  The  same  is  the  case  with  aphides,  which 
produce  males  only  when  the  weather  grows  cold  and  nutriment 
less  abundant.  In  true  retrogression,  on  the  other  hand,  there  is 
not  mere  latency,  but  absolute  loss.  A  hereditary  tendency  is 
eliminated  from  the  germ-plasm.  If  the  character  which  was  lost 
was  a  new  variation,  it  can  recur  in  the  race  only  through  another 
variation,  of  like  nature  ;  if  it  has  arisen  through  evolution,  through 
the  piling  up  of  progressive  variations  during  a  succession  of 
generations,  it  can  recur  only  through  a  similar  process  of  selection. 
It  is  conceivable,  of  course,  that  no  characters  are  ever  completely 
lost,  but  that  all  apparently  lost  characters  become  latent.  But 
this  implies  that,  though  the  germ-plasm  may  gain,  it  cannot  lose ; 
that  the  only  true  kind  of  variations  are  progressive  variations  ; 
and  that  while  it  is  possible  for  the  individual  to  vary  so  that 
he  completes  the  parental  development  and  adds  a  step,  it  is 
impossible  for  him  to  vary  so  as  not  to  complete  it,  except  by 
making  a  character  latent.  It  implies  that  all  the  variations  of 
the  two  parents,  the  four  grandparents,  the  eight  great-grandparents, 
of  all  the  billions  of  ancestors,  are  represented  in  the  germ -plasm  ; 
that  nothing,  not  even  a  minute  variation  in  a  hair,  that  ever 
appeared  during  the  immensely  long  and  varied  life-history,  has 
ever  been  lost ;  and  therefore,  that  a  human  embryo,  for  instance, 
has  latent  not  only  all  the  physical  and  mental  characters 
of  the  many  types  which  preceded  him,  but  all  the  variations  of 
these  characters  which  occurred  in  all  his  ancestors.  The  germ- 
plasm  in  a  microscopical  germ-cell  is  doubtless  a  very  complex 
entity,  but  this  hypothesis  would  endow  it  with  a  greater  number 
of  hereditary  tendencies  than  it  has  chemical  atoms.  In  truth  we 
have  no  choice  but  to  believe  that  hereditary  tendencies  may  not 
only  become  latent,  but  that  they  may  be  entirely  lost.  Indeed, 
when  we  remember  how  numerous  have  been  the  variations  and 
the  ancestors  of  every  individual,  and  how  immense  the  changes 
during  the  life-history,  it  is  evident  that  the  proportion  of  characters 
which  have  persisted,  either  in  a  patent  or  in  a  latent  condition, 
must  be  infinitely  small  when  compared  to  those  which  have  been 
altogether  lost — which  have  retrogressed  absolutely. 

189.  A  complete  discussion  of  latent  characters  may  be 
postponed  with  advantage.  We  need  note  only  that  when  a 
character,  for  example  the  gorgeous  plumage  of  Gallus  bankiva, 
the  wild  ancestor  of  our  domestic  poultry,  becomes  latent,  then 
(since  retrogression  and  reversion  are  identical)  subsequent 
retrogression,  which  eliminates  the  more  sober  colours  of  the 


1 1 6  RETROGRESSION 

domestic  bird,  and  so  permits  the  reappearance  of  the  ancestral 
traits,  may  present  every  appearance  of  progression.  Obviously, 
the  domestic  characters  which  were  new  to  the  race  and  which 
rendered  latent  more  ancient  traits,  result  from  progression,  and 
their  disappearance  and  the  consequent  reappearance  of  the  latent 
wild  characters  is  an  act  of  retrogression  as  well  as  reversion.  It 
may  happen,  of  course,  as  normally  occurs  in  the  case  of  the 
sexual  characters,  that  the  traits  of  the  domestic  fowls  are  not 
eliminated  when  the  wild  plumage  reappears,  but  replace  the  latter 
as  dormant  characters,  and  therefore  that  they  may  reappear  in 
descendants,  and  even  alternate  with  the  wild  traits  as  the  sexual 
characters  alternate  with  one  another  ;  but  the  fact  that  it  is 
sometimes  extremely  difficult  to  breed  out  hitherto  latent  ancestral 
characters  when  once  they  have  reappeared,  seems  to  indicate  that 
their  recrudescence  may  occasionally  be  due  to  a  loss  of  the  newer 
domestic  characters,  not  merely  to  the  latency  of  the  latter.1 

190.  It  will  be  worth  the  reader's  time  to  try  to  imagine  an  act 
of  retrogression  which  is  not  also  an  act  of  reversion.     To  take  an 
extreme  example  :  suppose  a  child  is  born  lacking  a  limb.     Experi- 
ence shows  that  a  deficiency  so  great  occurring  in  a  single  genera- 
tion usually  indicates  latency  rather  than  loss.     But  suppose  it  is  an 
instance  of  real  retrogression — i.e.  of  the  total  and  permanent  loss 
of  a   complex  hereditary   tendency  from  the  germ-plasm — then 
clearly  the  child  has  reverted  to  that  enormously  remote  ancestor 
in  whom  the  limb  did  not  exist.     It  is  not  maintained  of  course 
that  there  ever  was  a  period  during  the  life-history  when  three 
perfect  limbs  were  possessed  by  the  race  while  the  fourth  was 
lacking.     But  since   every   part  is   independently  variable,   it   is 
necessary  in  this  connection  to  think  of  every  part  separately. 

191.  Not  only  is  the  limb  independently  variable,   but   each 
smallest  part  of  it  possesses  the  same  power.     Suppose  a   child 
comes  into  existence  with  a  malformed  limb.     This  variation  may 
be  compounded  of  any  number  of  smaller  variations,  some  of  which 

1  "  I  may  here  add  a  remark  made  by  Mr  Wicking,  who  has  had  more  experi- 
ence than  any  other  person  in  England  in  breeding  pigeons  of  various  colours, 
namely,  that  when  a  blue,  or  a  chequered  bird,  having  black  wing  bars,  once 
appears  in  any  race  and  is  allowed  to  breed,  these  characters  are  so  strongly 
transmitted  that  it  is  extremely  difficult  to  eradicate  them  "  (Animals  and  Plants, 
vol.  i.  p.  210).  On  the  other  hand  if,  for  example,  albino  mice  be  crossed  with 
black-and-white  Japanese  waltzing  mice,  the  ancestral  grey  colour  appears,  but 
if  the  mongrels  be  inter-bred,  the  albino  and  the  black-and-white  types  reappear. 
In  this  case  the  albino  and  the  black-and-white  colour  become  merely  dormant 
when  the  grey  reappears.  Medelians  will  dispute  the  inference,  but  it  can  be 
substantiated  (see  chapter  vii.). 


THE  MASKING  OF  RETROGRESSION  117 

are  progressions  and  others  retrogressions.  If  we  think  of  each  of 
the  component  variations  separately,  and,  if  necessary,  analyse 
them,  we  see  that  every  progression  must  be  built  on  the  develop- 
ment as  presented  by  the  parent,  must  consist  of  an  addition 
after  a  complete  recapitulation  (as,  far  as  that  character  is  concerned) 
of  the  life-history  as  presented  by  the  parent ;  whereas  every 
retrogression  must  consist  of  a  subtraction  from  the  complete 
recapitulation — a  reversion.  Think  how  we  will,  puzzle  how  we 
may,  we  must  always  arrive  at  the  conclusion  that  retrogression  is 
identical  with  reversion. 

192.  There   are,    then,   two   kinds    of  'reversion.'       (i)   The 
individual   may    revert    ancestor-wards    through    retrogression — 
through  the  total  loss  of  a  developmental  potentiality  from  the 
germ-plasm.    (2)  He  may  reproduce  a  dormant  ancestral  trait.    The 
latter,  in  appearence  at  least,  is  also  reversion,  even  though  nothing 
is  lost  to  the  germ-plasm — even  though  the  more  modern   trait 
becomes  in  its  turn  merely  dormant.      Most  biologists  limit  the 
term  reversion  to  the  more  or  less  glaring  reproduction  of  a  latent 
ancestral  trait,  but  only,  I  think,  because  they  have  not  as  yet 
thought  of  retrogression  in  connection  with  reversion. 

193.  The  reason  why  retrogression  seldom*  presents  the  appear- 
ance of  reversion,  and  why,  therefore,  there  has  been  a  general 
failure  to  recognize  the  relations  between  the  two,  arises  from  the 
fact  that,  since   the   parts   of  the   individual   are   independently 
variable,  retrogressive  and  progressive  variations  are  usually  closely 
intermingled,  with  the  result  that  the  nature  of  the  former  is  masked. 
They  cannot  be  clearly  discerned  as  reversions.     Moreover,  in  old- 
established  types  especially,  the  majority  of  variations  tend  to  be 
of  very  small  magnitude.     Sometimes,  however,  retrogression   is 
extensive  and  affects  some  conspicuous  character  or  a  number  of 
characters  together,  and  then,  as  when   a  prize   breed  loses   its 
special   traits,    we   are  able   to   recognize  its  nature.      In  by  far 
the   great   majority   of  instances,   however,   retrogression   is   not 
obviously  identical  with  reversion.     Not  sight,  but  thought,  con- 
vinces us  of  the  identity.     Thus,  while  the  wing  of  a  bird,  whose 
latest  descendants  have  lost  the  power  of  flight,  was  evolving  from 
the  reptilian  fore-limb,  much  was  lost  as  well  as  gained.     Conse- 
quently when  the  wing  became  useless,  for  example  in  the  apteryx, 
and  retrogression  en   masse  set  in,  there  was  no   return  to   the 
reptilian  limb,  for  the  major  part  of  the  latter  had  already  under- 
gone retrogression  during  its  change  to  an  organ  of  flight. 

194.  Every   individual   varies   from    his    parent  in  an   almost 


1 1 8  RETROGRESSION 

infinite  number  of  ways.  A  proportion  of  his  variations  are  pro- 
gressive, and  of  them  the  great  majority  are  useless,  since  they  do 
not  make  the  child  superior  to,  that  is,  more  adapted  to  the  environ- 
ment, than  the  parent.  They  are  small  redundancies  which  do 
not  affect  the  survival  of  the  individual,  but  which,  if  reproduced 
by  subsequent  generations,  would  accumulate  and  ultimately  over- 
burden the  race.  We  may  note  many  of  them  in  any  human 
being,  but  we  cannot  by  mere  observation  form  any  conception  of 
their  number ;  for  nearly  all  of  them  are  too  obscure  and  minute  to 
be  recognizable  as  redundancies,  and  most  of  them  are  situated  in- 
ternally. But,  when  we  are  able  to  note  one  (e.g.  a  mole)  clearly  in  a 
parent,  we  are  almost  sure  to  find  it  lacking  when  we  examine  the 
child.  Natural  Selection  has  played  no  direct  part  in  its  elimination  ; 
yet  it  has  ceased  to  burden  the  race.  To  put  the  matter  in  another 
way :  no  individual  is  absolutely  perfect  in  every  particular,  and 
many  of  his  imperfections  are  due  to  progressive  variations. 
These  redundancies  are  not  as  a  rule  reproduced,  for  though  they 
occur  in  every  generation,  the  human  race,  for  example,  has  not 
altered  appreciably  in  shape  for  thousands  of  years.  That  is,  they 
do  not  accumulate.  They  disappear,  but,  very  obviously,  not  through 
selection.  Selection,  indeed,  could  not  reach  them,  for  singly  they 
do  not  affect  survival,  and  they  never  occur  en  masse  in  one 
individual  and  not  at  all  in  another.  The  evident  fact  is  that  the 
useless  progressive  variations  of  one  generation  tend  to  be  planed 
away  by  the  retrogressive  variations  of  the  next.  It  is  otherwise 
with  useful  progressions.  They  tend  to  be  preserved  by  selection, 
even  though,  paradoxical  as  it  may  sound,  they  are  in  many  cases, 
when  taken  separately,  beyond  the  reach  of  it.  In  a  future  chapter 
we  shall  study  the  very  admirable  device  by  which  the  elimination 
of  useless  and  preservation  of  useful  progressive  variations  is 
achieved  without  a  separate  elimination  of  individuals  for  each 
separate  kind  of  variation.1  Meanwhile  the  point  to  be  noted  is 
that  selection  plays  no  direct  part  in  the  retrogression  of  the 
mass  of  progressive  variations. 

195.  Every  multicellular  species  has  descended  from  unicellular 
organisms.  During  the  long  course  of  evolution  it  has  undergone 
innumerable  changes  of  form.  Many  structures,  which  once  were 
useful  and  for  that  reason  underwent  progression,  subsequently 
became  useless  and  retrogressed  utterly,  or  to  such  an  extent  that 
hardly  a  trace  of  them  remains  in  the  abbreviated  life-history  that 
is  narrated  in  the  development  of  the  latest  descendants.  Other 

1  See  chapter  ix. 


THE  ROLE  OF  RETROGRESSION  IN  EVOLUTION    119 

parts,  as  their  functions  and  anatomical  relations  changed,  have  been 
so  greatly  and  continually  modified  that,  like  a  much-mended 
garment,  the  original  structures  have  nearly  disappeared  and  have 
been  replaced  or  almost  replaced  by  new  material.  Others  again 
have  been  so  much  less  modified  that  the  careful  observer  is  able 
to  gather  a  good  deal  concerning  the  life-history.  In  yet  others, 
generally  the  more  modern  structures,  for  example  the  antlers  of 
the  stag,  the  life-history  is  plain  :  only  variations  which  were  never 
incorporated  into  the  life-history  of  the  race  have  vanished  ;  the 
structures  develop  in  the  individual  on  much  the  same  lines  as  they 
were  evolved  in  the  race.  In  every  species,  therefore,  we  find 
evidence  of  an  immense  amount  of  retrogression.  Consider,  for 
example,  how  much  man  must  have  lost  since  he  became  a  verte- 
brate, and  how  much  more  in  the  even  longer  antecedent  period. 

196.  Retrogression,  then,  has  been  as  much  a  part  of  evolution, 
of  adaptation,  as  progression.      It  has  planed  away  useless  and 
burdensome    structures.      It    has    straightened,    simplified,    and 
abbreviated    recapitulation ;  the  life-history  is  not  told   in  all  its 
details ;   the   narrative   is   limited  to   particulars  essential   to   its 
development  ;  and  thus  development  is  rendered  possible  during 
the   brief  lifetime   of  the    individual.       If  a   man,  for  example, 
recapitulated  all  the  changes  undergone  by  his  ancestors,  he  would 
require,  not  years,  but  ages  for  development.     Lastly,  retrogression, 
combined  with  some  progression,  has  rendered  possible  the  exist- 
ence of  the  developing  individual  in  environments  vastly  different 
from    those   inhabited    by   its   prototypes  of  the  ancestry.     The 
human  embryo,  for  instance,  dwells  within  its  mother's  uterus.     Its 
prototypes  had  an  independent  existence.     Were  they,  with  their 
structures  and  faculties  complete,  placed  in  the  uterus,  they  would 
perish  just  as  surely  as  the  embryo  would  were  it  placed  in  the 
ancestral  environments. 

197.  Within  the  uterus  the  embryo  leads  a  protected  vegetative 
life.     It  has  no  such  active  struggle  for  existence  as  the  adult. 
The  now  useless  power,  which  depends  on  structures  and  faculties, 
of  fighting  actively  for  itself,  as  did  its  prototypes,  who  lived  in  a 
world  where  nutriment  was  scarce  and  enemies  plentiful,  has  been 
lost  through  retrogression.    The  sole  business  of  the  embryo  is  to  fit 
itself  as  quickly  and  as  thoroughly  by  development  as  its  nature  per- 
mits for  the  battle  which  occurs  later.     Quick  development  implies 
quick  recapitulation,  which  in  turn  implies  abbreviated  recapitula- 
tion.   In  all  the  higher  animals  the  length  of  the  period  of  gestation 
is  always  proportionate  to,  and  therefore  presumably  dependent  on, 


120  RETROGRESSION 

the  amount  and  complexity  of  this  intra-uterine  preparation. 
Even  after  birth  the  young  of  the  higher  animals  are  protected  to 
give  time  for  still  more  development,  still  more  recapitulation, 
particularly  that  development  which  results  physically  from  use 
and  mentally  from  that  synonym  for  use,  experience.  Such  young 
animals,  owing  to  the  decay  (precisely  similar  to  that  observable 
in  the  embryo)  of  faculties,  especially  instincts,  present  in  the 
ancestry,  are  incapable  of  maintaining  independent  existence.  In 
brief,  whenever  the  active  struggle  is  abolished,  the  structures  and 
faculties  by  which  it  was  maintained  tend  to  disappear,  except  in 
so  far  as  they  serve  as  foundations  on  which  are  reared  characters 
that  are  useful  later  in  the  battle  of  life. 

198.  Animals  comparatively  low   in   the   scale   of  life,  many 
insects  for  instance,  do  not  protect  their  young  after  birth.     More- 
over, birth  occurs  at  an    early  period    of  development — that   is, 
when  offspring  have  recapitulated  nothing  or  comparatively  little 
of  the   life-history.     But  very   complex   and   rapid   development 
occurs  during  the  quiescent  period  in  the  egg-case.     To  take  the 
familiar  example  of  the  butterfly — the  caterpillar  when  he  emerges 
has  already  undergone  development  in  which  he  has  recapitulated 
a  vast  phase  of  the  evolution  of  his  race.     Next,  for  a  long  period, 
during  which  an  active  life  is  led,  very  few  structural  alterations, 
except  increase  in  size,  occur.     Probably  during  this  active  time 
the  environment,  speaking   relatively,  very  nearly   resembles  the 
ancestral   environments,  and  the  caterpillar  his  remote  ancestors 
who  developed  no  further.     Doubtless  he  differs  from  them,  but 
not  to  the  extent  that  the  embryo  in  the  egg-case  differs  from 
the  ancestors  it  represents.     The  structures  and  faculties  have  not 
undergone  the  same  amount  of  retrogression ;    the  life-history  is 
recapitulated  in  greater  detail.     The  function  of  this  active  period 
is  the  accumulation  of  nutriment  which  furnishes  material  both  for 
the  growth  of  the  caterpillar  and  for  his  subsequent  developments. 
Next  comes  another  period  of  quiescence  in  the  chrysalis,  which 
again   affords  opportunity  for  great  retrogression  and,  therefore, 
for  the  later  phases  of  the  life-history  to  be  very  rapidly  retold. 
In  this  period  occur  changes  which  swiftly  recapitulate  the  evolu- 
tion that  adoed  an  aerial  stage  to  the  development  of  a  hitherto 
purely  terrestrial  insect.     In   the  last,  the  active  butterfly  stage, 
however  long  it  may  endure,  there  is  again  complete,  or  almost 
complete  cessation  of  structural  alteration. 

199.  The  quiescent  periods  of  development  in  the  egg-case  and 
the  chrysalis  are  strictly  homologous  to  the  period  of  intra-uterine 


RETROGRESSION  IN  THE  EMBRYO  121 

development  in  the  higher  animals.  In  them  is  achieved  the  same 
end — the  fore-shortening  of  long  and  changeful  periods  of  the  life- 
history.  All,  or  almost  all  rapid  recapitulation  occurs  during 
periods  of  quiescence  when  the  individual  is  protected  or  con- 
cealed, that  is  when  he  is  least  exposed  to  selection.  Better  than 
anything  else  development  indicates  the  extent  to  which  the 
organism  is  a  bundle  of  adaptations.  Thus  the  embryo  of  the 
butterfly  develops  fast  while  it  is  stationary  in  its  egg-case,  where 
it  remains  till  food  is  abundant ;  the  active  caterpillar,  fitted  to  its 
environment  by  all  its  structures  and  instincts,  stores  nutriment  in 
its  tissues  against  a  time  when,  did  it  continue  active,  it  would  be 
very  disadvantageously  situated  while  changing  into  the  adult 
insect.  The  human  infant  is  born  to  a  mother  who  is  fitted  to  tend 
just  such  a  developing  being  at  just  such  a  stage  of  its  develop- 
ment. Were  its  development  different,  did  it  recapitulate  the  life- 
history  in  fuller  detail,  she  could  neither  bear  nor  tend  it.  In  both 
the  caterpillar  and  the  human  being  the  abbreviations  of  the  life- 
history,  though  happening  at  different  periods  of  life,  occur  at 
precisely  the  most  useful  periods.  After  the  period  of  reproduc- 
tion of  offspring  the  fitness  of  the  individual  to  the  environment 
declines — swiftly  in  the  lower  animals,  more  slowly  in  animals  that 
tend  their  young.  For  obvious  reasons,  Natural  Selection  can  no 
longer  preserve  it.  There  is  no  further  recapitulation.  There  is 
nothing  to  recapitulate. 

200.  Plants   lead    a   life  more  quiescent  than  most   animals. 
Speaking  generally,  the  seed  drops  to  the  ground,  and  the  young 
plant  emerges  from  it  into  an  environment  which  hardly  changes 
again  during  the  lifetime  of  the  individual,  but  which,  since  the  higher 
plants  have  evolved  from  lower  forms,  must  have  changed  greatly 
for  the  species.    In  them,  therefore,  retrogression  has  so  abbreviated 
a  major  portion  of  the  life-history  that  no  one  merely  examining 
the  embryo  of  an  oak,  for  example,  would  gather  more  than  a  hint 
of  the  immensely  long  and  changeful  process  by  which  the  species 
underwent  evolution. 

201.  We  see   then  how  great   a   part  retrogression  plays  in 
evolution  and  by  what  varied  devices  nature  assists  its  operations. 
It  swiftly  eliminates  the  useless  progressive  variations,  the  redund- 
ancies, which  occur  in  vast  numbers   in  every  individual.     More 
slowly,  in   proportion    to    their   antiquity,  it   rids  the   species   of 
characters    which   have    lost   their   utility.     It    abbreviates    and 
simplifies   development.     It   wars  against  progression,  but  great 
progression  would  be  impossible  without  it.     It  furnishes  a  half  of 


122  RETROGRESSION 

the  sum  of  adaptation,  leaving  only  the  other  half  to  the  direct 
action  of  Natural  Selection.  Yet  all  these  great  effects  result 
solely  because  in  every  structure  of  every  species  the  tendency  to 
vary  retrogressively  is  so  much  stronger  than  the  tendency  to  vary 
progressively  that  retrogression  is  checked  only  by  selection. 
Obviously  this  tendency  of  retrogressive  variations  to  preponderate 
over  progressive  variations  is  highly  adaptive — as  adaptive  as 
spontaneous  variability  itself.  The  question  then  arises  whether 
it  is  an  actual  adaptation  or  merely  something  which  has  arisen 
accidentally  during  the  course  of  evolution.  We  saw  that  the 
regulated  variability  which  distinguishes  all  forms  of  life  war 
beyond  reasonable  doubt,  maintained,  and  controlled  by  Natural 
Selection.  The  tendency  to  retrogression  is  only  one  of  the  ways 
in  which  variability  is  regulated.  We  have,  therefore,  every  reason 
to  suppose  it  is  no  chance  accompaniment  of  life,  but  an  adaptation 
ranking  in  universality  and  importance  with  spontaneous  varia- 
bility, insusceptibility,  and  recapitulation.  In  other  words,  we 
have  reason  to  believe  that  it  is  a  LA  vv  that  has  resulted  from  the 
selection  of  germ-plasms  which,  while  tending  to  vary  all  round  the 
specific  mean,  yet  tended,  on  the  whole,  to  vary  retrogressively. 

202.  The  problem  of  retrogression  cannot  be  approached  by 
any  of  the  laboratory  methods  and  therefore  tends  to  be  ranked 
by  some  minds  among  the  questions  of  *  philosophy.'     Moreover, 
the  very  simplicity  of  the  device  by  which  nature  achieves  such 
great  results  is  apt   to  awaken  incredulity.     I  can  only   ask  the 
reader,  while  bearing  in  mind  the  facts  of  adaptation  and  also  the 
fact  that  both  useless  progressive  variations  and  characters  that 
have  become  useless  tend  to  disappear  in  the  absence  of  direct 
selection,  to  try  here  again  to  conceive  interpretations  other  than 
those  I  have   suggested.     Judging  from    my   own    experience,    I 
think  he  will  fail. 

203.  We  conclude,  then,  that  the  great  mass  of  retrogression 
we  observe  in  nature  is  not  due  directly  to  Natural  Selection — that 
is  to  reversed  selection.     Since,  as  a  rule,  environments  change 
gradually,  it  occurs  under  conditions  which  afford  no   scope   to 
reversed  selection.     It  is  not  to  be  supposed,  for  example,  that  the 
apteryx  suddenly  abandoned  habits  of  flight.     While  the  struc- 
tures and  instincts  which  especially'fitted  it  for  a  terrestrial  life  were 
undergoing  progressive  evolution,  its  wings  were  still  helpful  in 
sustaining  existence.     But  they  became  continuously  less  useful, 
were    less   and    less   maintained    by   selection,    and    so    at    last 
underwent  retrogression.     Sometimes,  however,  we  may  observe 


THE  ROLE  OF  REVERSED  SELECTION  123 

what  appears  to  be  clear  evidence  that  reversed  selection  has 
caused  real  retrogression.  Thus  certain  blind  crabs  inhabiting 
caverns  have  lost  their  eyes,  but  not  the  stalks  on  which  the  eyes 
were  carried ;  since  the  eye  is  a  more  ancient  organ  than  the  stalk, 
it  should,  on  cessation  of  selection,  have  been  more  persistent ; 
yet  it  disappeared  first  Evidently  something  more  than  mere 
cessation  of  selection  was  at  work.  In  utter  darkness  the  eye,  a 
prominent  and  vulnerable  organ,  would  be  not  only  useless,  but 
worse  than  useless ;  and  therefore  reverted  individuals  would  be 
actively  selected  for  survival,  and  the  organ  would  be  more  rapidly 
eliminated  than  could  happen  under  cessation  of  selection.  In 
other  cave-dwelling  animals,  which,  as  we  suppose,  are  not 
descended  from  stalk-eyed  ancestors,  the  rudimentary  eye  is 
covered  by  skin.  Presumably  in  this  case  the  partial  retrogression 
has  resulted  from  mere  cessation  of  selection,  the  eye  being  pro- 
tected from  injury  and  therefore  from  reversed  selection  by  the 
progression  which  resulted  in  the  growth  of  the  skin.  Here,  as 
ever,  nature  has  followed  the  line  of  least  resistance. 

204.  But  though  reversed  selection  is  seldom  a  cause  of  retro- 
gression, it  has  nevertheless  a  very  important  function.  Reversed 
selection  implies  reversed  progression  of  the  race,  which,  in  turn, 
implies  reversed  development  of  the  individual.  When,  therefore, 
we  see  a  structure  better  developed  in  the  immature  individual 
than  in  the  adult,  we  may  be  sure  that  the  diminution  in  the  adult 
is  due  to  reversed  selection.  Thus  the  remote  ancestor  of  the 
modern  horse,  the  Hipparion,  had  three  functional  toes.  The 
embryo  of  the  horse  also  has  three  toes  of  considerable  size.  But 
the  two  outer  toes  in  each  limb,  which  in  the  embryo  are  nearly  as 
well  developed  as  in  the  Hipparion,  degenerate  partially  during 
development,  so  that  the  horse  is  born  with  only  one  functional 
toe.  "  Occasionally  a  foal  is  born  with  two  hoofs  on  one  or  more 
of  its  limbs  ;  at  very  long  intervals  a  foal  appears  with  three  hoofs 
on  one  or  more  of  its  limbs."  Now,  when  the  outer  toe  persists  in 
the  individual,  we  have  plainly,  in  a  real  sense,  an  arrest  of 
development.  The  toes  remain  in  the  embryonic,  the  ancestral 
condition  ;  the  whole  life-history  is  not  recapitulated.  But  in  the 
normal  horse  there  is  no  arrest  of  development ;  the  recapitula- 
tion is  carried  out  to  its  fullest  extent,  though  in  the  later  stages 
in  a  reversed  direction.  The  toes,  which  were  useful  to  the 
ancestors,  are  harmless  to  the  embryo,  but  would  be  harmful  to 
the  adult,  and,  there  .re.  '  .  e  been  eliminated  by  reversed  selec- 
tion in  the  latter  before  retrogression  has  eliminated  them  in  the 


124  RETROGRESSION 

former.  Still  better  examples  are  seen  in  the  disappearance  in 
later  life  of  structures  which  are  useful  to  the  developing  individual, 
but  which  have  no  place  in  the  scheme  of  adaptations  of  which  the 
adult  is  compacted.  It  is  because  of  "  selection  which  affects  not 
increase  of  an  organ  but  decrease  of  it,"  that  the  human  being 
loses  the  placenta,  the  frog  the  special  structures  of  the  tadpole, 
and  many  insects  their  larval  organs.  To  sum  up,  cessation  of 
selection  causes  real  retrogression,  a  real  loss  to  the  race  (i.e.  to 
the  germ-plasm)  of  ancestral  characters ;  reversed  selection,  on  the 
other  hand,  though  it  sometimes  collaborates  with  cessation  of 
selection  to  produce  real  loss,  causes,  as  a  rule,  like  ordinary  selec- 
tion, not  loss  but  gain  to  the  germ-plasm,  to  which  it  adds  a 
hereditary  tendency.  It  does  not  abbreviate  ;  on  the  contrary  it 
lengthens  the  life-history.  Speaking  generally,  it  causes  the  loss  in 
the  later  stages  of  development  of  characters  which  have  developed 
earlier.  That  is  its  special,  its  more  common  function. 

205.  In  the  present  work  we  have  accepted  Weismann's  theory 
of  the  continuity  of  the  germ-plasm.  That  theory  fits  the  facts  so 
well  that  it  has  very  few  opponents  at  the  present  day.  It 
supposes  that  the  germ-plasm  is  not  formed  afresh  in  every  germ- 
cell,  but,  by  means  of  cell-divisions,  is  handed  on  by  germ-cells 
to  descendant  germ-cells.  The  process  is  a  continuation  of  that 
which  occurred  in  the  unicellular  ancestors.  The  germ-plasm  varies 
and,  since  it  is  alive,  its  chemical  constituents  (carbon,  oxygen, 
nitrogen,  etc.)  change  in  a  constant  stream.  Nevertheless  from  age 
to  age  it  is  continuous  in  the  same  sense  as  the  human  body  is 
continuous  from  day  to  day.1  In  addition  we  have  supposed, 

1  As  far  as  I  am  able  to  judge,  this,  in  essence,  is  the  form  in  which  Weismann 
wishes  us  to  accept  his  theory.  He  writes  in  his  most  recent  work,  "  The 
expression  (ancestral  plasm),  however,  has  been  very  frequently  misunderstood, 
as  if  it  were  intended  to  mean  that  the  ids  retained  unchanged  for  all  time  the 
characters  of  their  respective  ancestors ;  and  I  have  even  been  credited  with 
supposing  that  our  own  ids  still  consist  of  the  determinant-complexes  of  our 
fish-like  or  amoeba-like  ancestors.  But  in  reality  no  id  exactly  or  completely 
corresponds  to  the  type,  that  is  to  the  whole  being  of  any  one  of  the  ancestors 
in  whose  germ-plasm  it  was  formerly  contained,  for  each  of  the  ancestors  had 
many  ids  in  his  germ-plasm,  and  his  entire  constitution  was  not  determined 
by  any  one  of  them  alone,  but  by  the  co-operation  of  them  all.  .  .  .  Thus,  accord- 
ing to  our  view,  the  germ-plasm  consists  of  ids,  each  of  which  contains  all  the 
determinants  of  the  whole  ontogeny,  but  usually  in  individually  different 
quality  "  (The  Evolution  Theory,  Eng.  Trans.,  vol.  ii.  p.  38).  Weismann's  con- 
ception of  the  germ-plasm,  then,  appears  to  be  of  a  substance  containing  discrete 
particles  which  he  terms  ids,  any  one  of  which  is  capable  of  directing  development. 
The  ids  differ  from  one  another,  but  only  in  so  far  as  is  implied  by  the  variations 
of  individuals.  As  noted  by  him,  the  term  '  ancestral  '  has  resulted  in  con- 
fusion ;  it  is  inaccurate  and  misleading.  TheTconception  of  the  germ-plasm 


THE  REPRESENTATION  OF  ANCESTORS  125 

what  none  will  dispute,  that  the  germ-plasm  is  the  bearer  of 
hereditary  tendencies  or  potentialities,  and  that  according  to  the 
nature  of  the  latter  is  the  nature  of  the  individual  which  springs 
from  the  germ-cell.  Further,  we  have  supposed,  what  very  few 
will  dispute,  and  what  indeed  is  implied  in  the  theory  of  continuity, 
that  the  germ-cell  receives  no  living  elements  from  the  somatic 
cells,  but  only  shelter  and  nutrition.  It  is  a  unicellular  organism 
living  in  the  midst  of  a  community  which  is  the  multicellular 
organism.  From  our  point  of  view,  therefore,  individuals,  for 
example  men,  are  nothing  more  than  dwellings  which  the  germ- 
plasm  builds  about  its  germinal  descendants.  It  follows — but 
here  we  are  contradicted  by  the  language  of  all  biological  literature 
— that  the  child  inherits  nothing  from  his  parent.  He  resembles 
his  parent  only  because  he  mimics  the  development  of  the  latter, 
only  because  his  development  was  directed  by  a  split-off  portion 
of  the  germ-plasm  that  directed  the  development  of  his  parent. 
Yet  again,  we  have  insisted  that  it  is  quite  inconceivable  that  the 
development  of  the  multicellular  individual  can  be  other  than  a  re- 
capitulation, more  or  less  altered,  of  the  life-history  of  his  race. 

206.  If  we  are  right,  then,  necessarily,  such  progressive 
variations  of  the  ancestors  as  have  not  been  lost  through  retro- 
gression, and  therefore  are  reproduced  in  development,  appear 
in  the  order  in  which  they  occurred  during  evolution,  the  sole 
exception  being  interpolated  variations.  In  a  general  sense, 
therefore,  successive  generations  of  ancestors  are  represented 
(mimicked)  during  development  in  order,  beginning  with  the 
unicellular  organism  which  is  represented  by  the  germ-cell,  and 
ending  with  such  progressive  variations  of  the  preceding  genera- 
tions as  are  reproduced  by  the  last  generation.  We  must  think 
in  terms  of  the  germ-plasm,  however,  and  bear  in  mind  that,  since 
retrogression  is  constantly  at  work,  even  in  characters  that  on  the 
whole  are  progressive  ;  since,  while  some  characters  have  undergone 

which  I  have  endeavoured  to  place  before  the  reader  is  that  of  a  substance  which 
contains,  or  is,  in  some  way,  associated  with  the  hereditary  tendencies  which  direct 
development.  I  suppose  that  the  germ-plasms  which  direct  the  development  of 
any  two  individuals  differ  qualitatively  somewhat.  Whether  or  not  the  germ- 
plasm  consists  of  discrete  units,  each  ofjwhich  contains  all  the  hereditary  tendencies, 
and  one  of  which  wholly  or  principally  directs  development,  is  a  question  I  do  not 
discuss :  I  know  of  no  facts  bearing  on  the  matter  and  no  means  of  testing  the 
thinking.  But,  as  will  be  seen,  I  do  very  strongly  protest  against  the  hypothesis 
that  the  germ-plasm  consists  of  discrete  particles  each  of  which  represents  a 
particular  ancestor.  That  hypothesis,  I  think,  is  not  only  not  warranted  by 
valid  evidence,  but  is  negatived  by  the  high  probability  that  the  germ-plasm  is 
continuous  in  a  real  sense  from  generation  to  generation. 


126  RETROGRESSION 

progression,  others  have  undergone  retrogression  or  have  re- 
mained stationary,  and  since  variations  have  been  interpolated, 
no  generation  of  ancestors  is  ever  reproduced  exactly  by  descen- 
dants. Therefore  the  statement  that  ancestors  are  represented  in 
orderly  succession  (in  the  order  in  which  they  came  into  existence) 
is  true  in  a  general  and  vague  sense  only. 

207.  Apparently,   however,  many  biologists  believe,  not   that 
the  germ-plasm    undergoes  such  a   change  during  evolution  that 
development  is  in  a  general   sense    a   recapitulation  of  the  life- 
history,  not  that  the  successive  generations  of  ancestors  are  vaguely 
mimicked  in  turn   during   development,   but   that  each  ancestor 
adds  to  the  germ-plasm  a   *  unit '   or    '  contribution '  which   may 
control,  or  may  assist  in  controlling,  development  from  start  to 
finish,  from  germ-cell  to  adult. 

208.  The  best  known  of  the  hypotheses  which  are  founded  on  the 
notion  of  ancestral  contributions  is  Sir  Francis  Galton's  *  Law  of 
Ancestral  Inheritance.'    This  hypothesis,  or  modifications  of  it,  which 
differ  in  detail  but  are  similar  in  principle,  have  been  so  widely 
accepted  that  it   is  necessary  to    discuss  it  somewhat  at  length. 
Galton  analysed    statistical  data   concerning  stature,    eye-colour, 
artistic  faculty,  and  health,  collected  from  about  one  hundred  and 
fifty  families  of  human  beings,  and  extending  over  three  or  more 
generations.     Next,  he  analysed  statistics  concerning  the   colour 
of  Bassett  hounds,  a  race  of  dwarf  blood-hounds   originated  by 
Sir  Everett  Millais  some  twenty  years  previously.     He  concluded, 
"  The  two  parents  contribute  between  them  on  the  average  one-half 
(or  0.5)  of  the  total  heritage  of  the  offspring  •  the  four  grandparents 
one-fourth    (or   O-5)2;    the   eight    great-grandparents   one-eighth 
(or  o.5)3,  and  so  on.     Thus  the  sum  of  the  ancestral  contributions 
is  expressed  by  the  series  (o.5)  +  (o.s)2  +  (o.5)3,  etc.,  which,  being 
equal  to  unity,  accounts  for  the  whole  heritage."  x 

209.  Now  obviously  Galton's  statistics  do  not  furnish  evidence 
that  ancestors  contribute  units  to  the  germ-plasm.    That  deduction, 
if  it  is  in  his  mind,  is  drawn  from  the  observation  that  offspring 
may,  in  this  or  that  character,  resemble  ancestors  more  than  they 
do  parents.     Probably  it  was  reached  before  the  statistics  were 
collected.     Galton  merely  noted  certain  resemblances  between  the 
individuals  of  three  or  four  generations,  and  calculated  that  on  the 
average  offspring   resemble   each  parent   to   the    extent   of  one- 
quarter  of  their  total  characters,  each  grandparent  to  the  extent 

1  The  Average  Contribution  of  each  Several  Ancestor  to  the  Total  Heritage  of  the 
Offspring,  Proc.  Roy.  Soc.  London,  vol.  Ixi.  pp.  401-13. 


THE  LAW  OF  ANCESTRAL  INHERITANCE          127 

of  one-sixteenth,  and  so  on.  He  concluded  further,  that  what  was 
true  of  the  characters  investigated  was  true  of  all  characters,  that 
what  was  true  of  the  generations  investigated  was  true  of  all 
generations,  and  seemingly  also  that  the  resemblances  were  due 
to  '  contributions  '  to  the  germ-plasm.  The  notion  that  ancestors 
'contribute'  to  the  heritage  of  the  child  (i.e.  add  definite  and 
apparently  discrete  '  units '  to  the  germ-plasm)  is  founded  on,  but 
not  tested  by  his  facts. 

210.  The  principal  difficulty  in  discussing  the  Law  of  Ancestral 
Inheritance   arises    from    the   fact    that   since    the    nature   of  a 
1  contribution '   is  not  defined,  the  hypothesis  is  not  '  definite  in 
conditions.'     Conceivably,    the   word   implies   a    variation   which 
occurred  in  the  germ-plasm  at  the  time  that  an  ancestor  existed — 
a  variation  which  may  or   may  not   blend  with  other  variations 
occurring  in  the  same  and  in  preceding  and  succeeding  generations. 
Or  '  contributions '  may  be  regarded  as  discrete  units  which  re- 
present separate  ancestors  in  the  germ-plasm  and  have  been  added 
to  it  by  them.     Since  biometricians,  as  a  rule,  hold  with  Weismann 
that  the  germ-plasm  is  continuous  and  that  inheritance  is  usually 
blended,  it  seems  correct  to  conclude  that  what  they  mean   by 
their  word  '  contribution '  is  a  blend  of  the  variations  occurring  in 
a  generation  of  ancestors.     On  the  other  hand  the  language  used 
appears  to  indicate  clearly  that  what  they  mean  is  that  the  germ- 
plasm  is  compounded  of  discrete  units,  each  of  which  was  somehow 
contributed  by  a  separate  ancestor — contributed  by  the  soma  to 
the  germ-plasm,  by  the  dwelling  to  the  inhabitant.     Probably  such 
an  interpretation  would  be   repudiated.     Nevertheless,  it   would 
certainly   seem   to    be   implied   that   discrete   units   representing 
ancestors  do  in  some  way  come  into  existence  in  the  germ-plasm 
and  influence  the  development  of  the  individual  from  start  to  finish. 

211.  "We  seem  to  inherit  bit  by  bit,  this  element  from  one 
progenitor,   that  from   another  .  .  .  while   the  separate   bits   are 
themselves  liable  to   some  small   change   during   the   process  of 
transmission.     Inheritance  may  therefore  be  described  as  largely 
if  not  wholly  '  particulate,'  and  as  such  it  will  be  treated  in  these 
pages.     Though  this  word  is   good   English  and    accurately  ex- 
presses its  own  meaning,  the  application  now  made  of  it  will  be 
better   understood   through   an  illustration.     Thus,    many  of  the 
modern  buildings   in    Italy   are  historically  known  to  have  been 
built  out  of  the  pillaged  structures  of  older  days.     Here  we  may 
observe  a  column  or  a  lintel  serving  the  same  purpose  for  a  second 
time,  and  perhaps  bearing  an  inscription  that  testifies  to  its  origin, 


128  RETROGRESSION 

while  as  to  the  other  stones,  though  the  mason  may  have  chipped 
them  here  and  there,  and  altered  their  shapes  a  little,  few,  if  any, 
came  direct  from  the  quarry.  This  simile  gives  a  rude  but  true 
idea  of  the  exact  meaning  of  Particulate  Inheritance,  namely,  that 
each  piece  of  the  new  structure  is  derived  from  a  corresponding 
piece  of  some  older  one,  as  a  lintel  was  derived  from  a  lintel,  a 
column  from  a  column,  a  piece  of  wall  from  a  piece  of  wall. 

212.  "I  will  pursue  this  rough  simile  just   one   step  further, 
which  is  as  much   as  it   will  bear.     Suppose  we  were  building  a 
house  with  second-hand  materials  carted  from  a  dealer's  yard,  we 
should  often  find  considerable  portions  of  the  same  old  houses  to 
be  still  grouped  together.    Materials  derived  from  various  structures 
might  have  been  moved  and  much  shuffled  together  in    the  yard, 
yet   pieces   from   the   same  source   would    frequently   remain    in 
juxtaposition  and  it  may  be  entangled.     They  would  lie  side  by 
side  ready  to  be  carted  away  at  the  same  time  and  to  be  re-erected 
together  anew.     So  in  the  process  of  transmission  by  inheritance, 
elements  derived  from  the  same  ancestor  are   apt  to   appear  in 
large  groups,  just  as  they  had  clung  together  in  the  pre-embryonic 
stage,  as  perhaps  they  did.     They  form  what  is  expressed  by  the 
words  '  traits ' — traits   of  feature   and    character — that   is  to  say 
continuous  features  and  not  isolated  points. 

213.  "  We  appear,  then,  to  be  severally  built  up  out  of  a  host 
of  minute  particles  of  whose  nature  we  know  nothing,    any  one 
of  which  may  be  derived  from  any  one  progenitor,  but  which  are 
usually    transmitted   in    aggregates,    considerable   groups    being 
derived  from  the  same  progenitor.     It  would  seem  that  while  the 
embryo  is  developing  itself,  the  particles  more  or  less  qualified  for 
each  new  post  wait  as  it  were  in  competition,  to  obtain  it.     Also 
that   the   particle   that  succeeds,  must  owe  its  success  partly  to 
accident  of  position  and  partly  to  being  better  qualified  than  any 
equally  well  placed  competitor  to  gain    a  lodgment.       Thus  the 
step  by  step  development  of  the  embryo  cannot  fail  to  be  influ- 
enced by  an  incalculable  number  of  small  and  mostly  unknown 
circumstances."  x 

214.  Many   biologists    evidently  do  mean    by   'contribution' 
a  unit  added  to  the  germ-plasm.     For  example,  we  are  told,  "  The 
Law  of  Ancestral  Inheritance  proves  that  all  ancestors,  however 
remote,  are  able  to  leave  the  impress  of  their  individuality  upon 
the  sex-cells  in  diminishing  proportion  according  to  their  remote- 
ness.    Such  a  fact  can  only  be  accounted   for  by  assuming  the 

1  Galton,  Natural  Inheritance,  pp.  7-9. 


THE  LAW  OF  ANCESTRAL  INHERITANCE         129 

existence  in  the  germ-plasm  of  definite  units  carrying  definite 
characters,  and  the  regular  halving  in  the  average  strength  or 
amount  of  such  characters  during  the  reducing  division  of  the 
nuclear  matter  of  the  sex-cells  which  precedes  each  act  of 
reproduction."  1 

215.  Apparently,  then,  each  ancestor  is  supposed  to  contribute 
a  unit  to  the  germ-plasm,  which,  since   the   contributions   taken 
together  amount  to  unity,  is  thus  totally  compounded  of  ancestral 
units — two  large  units  from  the  parents,  four  units  each  a  quarter  as 
large  from  the  grandparents,  and  so  on.    But  each  ancestor's  unit  is 
also  totally  compounded  of  units  from  his  ancestors,  whose  units  in 
turn  are  totally  compounded  of  units  from  their  ancestors,  and  so  on 
in  endless  recession.     Now,  imagine  a  line  of  individuals,  A,B,  .  .  . 
Y,Z.     Then  Z  will  have  a  unit  from  A.     He  will  also  have  one 
from  B  (which  will  contain  a  contribution  from  A).     Likewise,  he 
will  have  one  from  C  (which  will  contain  a  contribution  from  A 
and  one  from  B  [which  will  contain  one  from  A]).     Yet  again  Z 
will  have  a  unit  from  D  (which  will  contain  a  contribution  from 
A  and  one  from  B  [which  will  contain  one  from  A]  and  another 
from  C  [which  will  contain  a  contribution  from  A  and  one  from  B 
{which  will  contain  a  contribution  from  A}]) — and  so  on.    Obviously 
A's  unit  will  be  repeated  many  times  over,  in  almost  infinite  sub- 
division, in  all  the  contributions  of  his  descendants.     So,  also,  as 
regards  B's  unit  and  the  units  of  the  other  ancestors,  especially  the 
more  remote.     Really,  however,  ancestral  contributions  have  not 
this   ideal   simplicity  of  composition ;   for  every  individual  is  of 
almost  infinitely  long  descent,  and  if  of  a  sexually  dimorphic  species, 
has  two  parents,  four  grandparents,  eight  great-grandparents,  and 
so  on. 

216.  At  first  sight  a  law  of  ancestral  contributions  seems  simple  : 
we  suppose  merely  that  each  ancestor  adds  something  representing 
himself  to  the  germ-plasm.     If,  however,  we  make  the  necessary 
rigorous  deductive  inference  of  consequences,  it  becomes  almost 
unthinkable.     It  is  opposed,  in  language  at  any  rate,  to  the  notion 
that  the  ancestors  of  the  germ-cells  are,  not  '  individuals,'  but  the 
cells  of  the  germ-tract,  which  merely  dwell  within  the  individuals. 
Notwithstanding  all  its  appearance  of  mathematical  precision,  it  is 
so  vaguely  expressed  that  I  doubt  if  any  two  people  understand  it 
alike.2     I  describe  it  as  I  understand  it,  or  as  far  as  I  am  able  to 

1  Vernon,  Variations  in  Animals  and  Plants,  pp.  134-5. 

2  "  This  law,  that  the  mean  Characters  of  the  offspring  can  be  calculated  with 
the  more  exactness,  the  more  extensive  our  knowledge  of  the  corresponding  characters 

9 


130  RETROGRESSION 

understand  it.  Presumably  a  'contribution'  to  the  heritage  of  a 
descendant  means  more  than  mere  resemblance;  otherwise  it  is 
difficult  to  understand  why  a  word  so  apt  to  mislead  is  used  when 
the  unequivocal  word  '  resemblance,'  which  occurs  readily  to  the 
mind,  is  sufficient  to  describe  the  phenomenon.  An  ancestral  con- 
tribution which  is  halved  and  quartered  and  so  forth  would 
certainly  seem  to  imply  a  discrete  unit  representing  an  ancestor  in 
the  germ-plasm  ;  and  apparently  since  every  ancestor's  heritage  is 
compounded  from  those  of  his  predecessors,  it  would  appear  also 
that  the  contribution  of  every  ancestor  is  represented  in  the 
contribution  of  every  successor.  To  say  the  least,  it  is  hard 
to  believe  that  machinery  for  this  perpetual  and  complicated 
division  can  exist.1 

of  the  ancestry,  may  be  termed  the  Law  of  Ancestral  Heredity  "  (Mr  Udney  Yule, 
"  Mendel's  Laws  and  their  Probable  Relations  to  Intra-racial  Heredity,"  The 
New  Philologist,  1902,  p.  202.  "  The  degree  to  which  a  parental  character  affects 
offspring  depends  not  only  upon  its  development  in  the  individual  parent,  but  on 
its  degree  of  development  in  the  ancestors  of  that  parent  "  (Prof.  W.  F.  R.  Weldon). 
Mr  Yule  and  Professor  Weldon  avoid  the  use  of  the  word  contribution.  As 
formulated  by  them  the  Law  expresses  what  would  appear  an  obvious  truth  ; 
but  it  is  then  widely  different  from  the  Law  as  formulated  by  Galton  and 
accepted  by  Mr  Vernon. 

1 1  have  reasoned  from  what  appears  to  me  the  plain  meaning  of  Galton's 
words.  Here  is  another  and  apparently  very  similar  interpretation  :  "A  man 
may  receive  a  quarter  of  his  hereditary  characters  from  each  parent,  and  a  six- 
teenth from  each  grandparent,  but  all  except  a*  very  minute  portion  of  these 
characters  are  common  to  all  men,  they  being,  in  fact,  the  characters  proper  to 
the  species,  Homo  sapiens,  as  such.  Instead  of  a  quarter  of  a  unit  from  each  parent 
a  man  receives  only  a  hundredth  or  a  thousandth  of  a  unit  of  characters  peculiar 
to  the  parents  as  such,  all  the  rest  being  the  characters  common  to  all  the  members 
of  the  race.  Even  this  minute  fraction  of  a  unit  does  not  in  any  way  represent 
characters  acquired  by  the  parent  during  his  lifetime,  but  is  itself  built  up  of 
proportions  of  peculiar  characters  received  from  his  parents,  grandparents,  and 
other  ancestors  in  accordance  with  the  law  of  heredity  "  (Vernon,  Variations  in 
Animals  and  Plants,  pp.  146-7).  Presumably  Dr  Vernon  does  not  intend  to  imply 
that  a  man  receives  a  quarter  of  his  bulk,  his  mass,  from  each  parent.  Extension 
and  weight  are  derived  wholly  from  nutriment.  We  must  go  back,  therefore, 
as  always  in  the  study  of  heredity,  to  the  germ-plasm,  or  rather  to  its  hereditary 
potentialities.  If  I  understand  Dr  Vernon  aright,  he  accepts  the  theory  of  discrete 
ancestral  units  which  are  halved  and  quartered  and  so  on  in  the  germ-plasm,  but 
thinks  that  all  ancestral  units,  at  any  rate  all  units  that  have  come  into  existence 
since  man  evolved,  are  much  alike — i.e.  he  thinks  that,  apart  from  the  potency 
due  to  bulk,  units  differ  only  in  comparatively^insignificant  details  ;  just  as  men 
are  alike  in  being  men,  but  differ  inasmuch  as  they  vary  somewhat  from  one  another. 
The  hand  is  a  character  "  proper  to  the  species,  Homo  Sapiens,  as  such."  Is  it 
then  contended  that  the  child  derives  one-quarter  of  his  tendency  to  develop 
that  organ  under  the  stimuli  of  nutrition  and  use  from  each  parent,  one-sixteenth 
from  each  grandparent,  and  so  on  ?  The  theory  of  Ancestral  Inheritance  assumes 
that  the  influence  of  an  ancestor  eleven  generations  back  is  on  the  average  more 
than  a  billion  times  weaker  than  that  of  parent.  But  the  character  of  a  particular, 


THE  REDUCTION  DIVISION  131 

217.  The  hypothesis  that  ancestral  contributions  are  halved  in 
every  generation  is  a  deduction  from  Galton's  (and  other)  statistics, 
and  from  the  circumstance  that  a  '  reduction '  division  occurs  in 
the  germ-tract.     So  much  has  been  made  of  the  reduction  division 
that  it  is  necessary  to  consider  it.    It  commonly  happens  that  when 
cells  are  about  to  multiply  by  self-division  the  '  chromatin '  of  each 
nucleus  gathers  into  *  rods '  or  masses   termed  chromosomes,  the 
number  of  which  is  definite  for  each  species.     "  Thus  in  man  we 
find  32,  in  a  mouse  24,  in  a  donkey  36,  in  a  cockroach  32,  in  Ascaris 
megalocephala,  var.  univalens,  2 ;  var.  bivalens,4,  and  so  on  in  different 
organisms."1    In  ordinary  cell  division  the  chromosomes  split,  each 
half  from  each  chromosome  forming  a  new  chromosome  which  passes 
to  one  of  the  daughter  cells.    The  division  of  the  cells  thus  extends 
to  a  minute  division  of  the  structures  within  them.    In  this  way  the 
normal  number  of  the  chromosomes  is  preserved.     But  when  the 
cells  of  the  germ-tract  are  about  to  produce  actual  germs  fit  for 
conjugation,  the  chromosomes  do  not  split.     In  the  case  of  sperms, 
half  of  them  pass  as  entire  bodies  to  each  daughter  cell,  which  thus 
receives  only  half  the  normal  number  of  chromosomes.     This  is 
the  'reduction'  division.     A  second  division  in  which  the  chromo- 
somes split,  results  in  four  cells,  each  of  which,  possessing  half  the 
usual  number  of  chromosomes,  becomes  a  spermatozoon.     In  the 
case  of  the  ovum,  four  cells  are  not  formed ;  when  the  reduction 
division  occurs,  one-half  of  the  total  number  of  chromosomes  are 
cast  out  of  the  cell  in  a  '  polar '  body,  leaving  almost  the  whole  of 
the  cell-body  to  the  remaining  chromosomes.     At  the  next  division 
the  reduced    number  of  chromosomes  split   as  in  ordinary   cell- 
division  ;  but  one-half  of  the  product  is  again  cast  out  of  the  cell 
as  a  second  polar  body,  leaving  the  ripened  ovum,  like  the  ripened 
sperm,  with  only  one-half  of  the  normal  number  of  chromosomes. 
Therefore  the  divisions  which  result  in  four  cells  in  the  case  of  the 
sperms,  result  only  in  one  in  the  case  of  the  ova. 

218.  An    obvious   interpretation   of  these  phenomena  is   that 
reduction  implies  nothing  more  than  a  preparation  for  conjugation  ; 
for,  if  the  number  of  chromosomes  were  not  reduced  to  half,  they 
would  be  doubled  in  each  generation  when  sperm  united  with  ovum, 

for  example  albino,  ancestor  more  remote  than  the  eleventh  may  be  reproduced 
by  offspring  to  the  exclusion  of  the  character  of  more  recent  ancestors.  His 
'  unit,'  therefore,  must  be  strong  enough  to  direct  development.  Must  we 
assume,  therefore,  that  the  germ-plasm  is  compounded  of  millions  or  billions  of 
units,  the  more  modern  of  which  are  millions  or  billions  of  times  more  potent  than 
is  necessary  for  the  reproduction  of  a  character  ? 
1  C.  E.  Walker,  The  Essentials  of  Cytology,  p.  21. 


132  RETROGRESSION 

and  this  process  would  continue  indefinitely.  An  obvious  interpre- 
tation of  the  occurrence  of  polar  bodies  is  that  they  are  abortive 
cells — abortive  because  the  ovum  has  retained  almost  the  whole 
of  the  cell-body  and  the  contained  food,  for  lack  of  which  the 
polar  bodies  perish.  Neither  of  these  interpretations  can  be  tested  ; 
they  are,  from  the  nature  of  the  case,  merely  working  hypotheses. 
In  science  guesses  should  be  avoided  if  possible;  but,  at  any 
rate,  the  guess  that  the  extension  of  the  polar  bodies  is  a 
mere  detail  in  the  preparation  of  the  ovum  for  conjugation  is 
at  least  as  likely  to  be  correct  as  the  guess  that  reduction 
implies  a  halving  of  ancestral  contributions.  Moreover,  when  uni- 
cellular organisms  unite,  mixing  their  nuclei  but  not  their  cyto- 
plasm, as  happens  in  some  cases,  there  is  no  extrusion  and  death 
of  polar  bodies.  The  notion  that  polar  bodies  are  merely  cells 
which  perish  from  lack  of  cytoplasm  and  nutriment  is  supported, 
besides,  by  the  fact  that,  before  disintegrating,  their  chromosomes 
usually  multiply  by  splitting  as  in  ordinary  cell-division.  Probably, 
therefore,  extrusion  and  death  are  not  essential  parts  of  the  process, 
but  only  the  means  by  which  a  double  or  quadruple  supply  oi 
nutriment  is  conferred  on  the  ovum  wherewith  to  start  the  new 
cell-community.  However,  as  we  see,  reduction  has  been  held  to 
indicate  a  halving  of  ancestral  contributions — an  enormous  but 
untestable  deduction. 

219.  On  the  other  hand,  suppose  by  an  'ancestral  contribution' 
is  meant,  not  a  unit  representing  an  ancestor  in  the  germ-plasm 
and  added  to  it  by  him,  but  a  variation  which  has  occurred  in  it 
at  the  time  he  came  into  existence.     Then,  since  each  individual, 
on  the  average,  contributes  a  quarter  of  the  heritage  of  his  child, 
we  must  suppose  that  he  varied  from  his  parents  to  the  extent  of  one- 
quarter  of  the  sum  of  his  characters.     His  parents  did  the  same, 
and  so  does  the  child.     Therefore,  on  the  average,  the  child  varies 
to  the  extent  of  three-quarters  from  its  great-grandparents.     But 
were  this  true  of  all  characters,  so  rapid  would  be  the  rate  of  racial 
change,  that  a  human    being,  for   example,  would  become  non- 
human  in  three  generations.     If  it  be  argued  that  the  variations 
of  the  individual  from  his  parent  do  not  imply  variations  from 
remote   progenitors,   then    how    are    the    several   'contributions' 
to  be  distinguished  from  one  another  ?     How  is  it  known  that,  on 
the  average,  each  parent  contributes  a  quarter,  each  great-grand- 
parent a  sixteenth,  and  so  on  ? 

220.  The    immense   rate    of   change   indicated    by    Galton's 
statistics  is  due  apparently  to  the  fact  that  he  investigated  only 


BIOMETRY  133 

variable  characters  in  very  variable  species.  He  himself  terms  the 
chosen  characters  'moderately  exceptional.'1  Bassett  hounds 
were  established  very  recently,  and  display  the  variability  of  new 
types.  In  many  characters  human  beings  display  the  variability 
which  follows  cessation  of  selection.  The  reproduction  of  coat- 
colour  in  the  lower  animals,  and  of  eye-colour  in  men,  tends  to  be 
'  alternative.' 2  Probably  human  stature  has  never  been  very  rigidly 
fixed  by  Natural  Selection,  and  variability  has  been  influenced,  in 
England  at  any  rate,  by  a  great  intermixture  of  races.  Artistic 
faculty  and  health  are  not  only  very  variable,  but  develop  under 
the  influence  of  an  environment  which,  as  regards  these  characters, 
is  very  varied.3 

221.  Not  until  ancient,  stable,  non-exceptional  characters,  for 
example  heart,  lungs,  and  the  like,  have  been  investigated  shall  we 
be  in  a   position   to  formulate   or   perceive   the  impossibility  of 
formulating  a  numerical  Law  of  Ancestral  Heredity  (i.e.  to  indicate 
the  average  rate  of  reversion).     When  that  is  done,  I  think  it  will 
be  admitted  that  variability,  including  the  tendency  to  reversion, 
is  an  adaptation   regulated  by  Natural  Selection,  and,  therefore, 
that  the  degree  of  variability  differs  with  the  stringency  of  Natural 
Selection  in  every  species  and  character.     I  think,  also,  that  it  will 
then  be  admitted   that   the  true  Law  of   Ancestral   Heredity  is 
formulated  when  we  declare  that,  In  any  character  the  tendency 
to  retrogression  (i.e.  reversion  to  ancestors)  is  proportionate,  on  the 
average,  to  the  speed  of  the  antecedent  progression. 

222.  The  Law  of  Ancestral  Inheritance  is  an  example  of  the 
biometric  and  statistical  method  of  inquiry.     As  a  method  biometry 
is,  of  course,  like  experiment,  excellent.     It  enables  the  patient 
worker  to  gather  many  obscured  truths  which,  but  for  it,  would 
lie  beyond  our  reach.     But  it  is  extraordinarily  slow  and  laborious, 
and,  like  experiment,  has  its  limitations  as  a  means  of  discovery 
and  as  a  test  of  thinking.    So  many  biological  facts  are  patent,  and 
so  much  biological  thinking  can  be  tested  by  reference  to  this  patent 
evidence  that,   apparently,  it  has  been  difficult  to  find   subjects 
suitable  for  biometric  inquiry,  except  when  the  patent  evidence 
is  ignored.     Occasionally,  therefore,  such  inquiry  has  been  directed 
to  the  discovery  of  matters  already  known,  or  which  can  be  made 
known  at  a  thousandth  part  of  the  labour  involved  and  with  an 
even  greater  degree  of  certainty.     Inferences  founded  on  materials 
furnished  by  biometry  require  to  be  tested  as  carefully  as  any  other ; 
but,  as  in  experiment,  the  two  functions  of  discovery  and  testing 

1  Natural  Inheritance,  p.  i.         2  See  §§  239,  277,  278.         3  See  chapter  xxii 


134  RETROGRESSION 

are,  apparently,  frequently  confused,  and  thoughts  are  claimed 
as  accurate  merely  because  they  are  based  on,  not  tested  by, 
statistical  data. 

223.  In  the  Law  of  Ancestral  Inheritance  we  have  an  instance 
of  an  induction  expanded,  but  not  tested  by  a  deduction,  the  latter 
being  regarded  as  the  theory.     Here  the  induction  is  that,  on  the 
average,  offspring  resemble  ancestors  (at  any  rate  in  certain  characters 
and  within  three  or  four  generations)  in  the  stated  degrees.     The 
deduction — the  really  tremendous  expansion  of  the  induction — is 
that  ancestors  contribute  in  the  stated  degrees  to  the  heritages  of 
descendants.     Though  the  universe  is  a  unity,  the  facts  and  '  laws ' 
of  which  are  in  harmony  with  one  another,  and  it  is  the  mission  of 
science  not  only  to  interpret  the  facts  in  terms  of  the  laws  but  also 
to  demonstrate  the  relations  between  the  latter,  no  appeal  is  made 
to  any  conceived  system  of  reality.     The  axiom  that  every  induc- 
tion must  be  used  as  a  basis  for  a  rigorous  deductive  inference  of 
consequences  is  disregarded.     In  other  words  the  correctness  of  the 
thinking,  as  distinguished  from  the  facts,  is  left  untested. 

224.  The  law  evidently  bears  on  the  theory  of  the  Continuity 
of  the  Germ-plasm,  which  supposes  that  the  parents  and  ancestors 
of  the  individual  contribute  nothing  to  the  child,  and  on  the  theory 
of  Recapitulation,  which  supposes  that  ancestors  are  represented 
during  development,  not  en  masse,  but  serially ;  but  no  attempt  is 
made  to  show  that  it  accords  with  these  hypotheses,  or,  if  it  does 
not,  in  what  respects  they  are  wrong.     It  remains  as  apart  from 
anything  else  that  is  known  or  that  has  been  surmised  by  science 
concerning  living  beings  as  a  miracle. 

225.  The  Law  of  Filial  Regression  furnishes  another  instance  of 
biometric   work.     It  has  been  ascertained  that  when  a  group  of 
parents  differs  in  any  particular  from  the  mean  or  average  (medio- 
crity) of  their  race,  the  offspring  on  the  average  differ  less,  grand- 
children still  less,  and  so  on.     In    other  words,   if  a  group   (or 
individual)  in  any  generation  differs  from  the  racial  mean,  its  (or 
his)  predecessors  and  successors   will,  as   a    rule,  be  found  less 
different.      "Thus  take  fathers  of  stature  72",   the  mean  height 
of  their  sons  is  /O'S",  or  we  have  a  regression  towards  the  mean 
of  the  general  population.  .  .  .  The  father  with  a  great  excess  of 
the  character  contributes  sons  with  an  excess,  but  a  less  excess  of 
it ;  the  father  with  a  great  defect  of  the  character  contributes  sons 
with  a  defect,  but  less  defect  of  it.    The  general  result  is  a  sensible 
stability  of  type  and  variation  from  generation  to  generation.  .  .  . 
Now  a  man  is  not  only  the  product  of  his  father,  but  of  all  his 


RETROGRESSION  AND  REGRESSION  135 

past  ancestry,  and  unless  very  careful  selection  has  taken  place, 
the  mean  of  that  ancestry  is  probably  not  far  from  that  of  the 
general  population." 1  The  induction  here  is  that  there  exists  a 
tendency  for  exceptional  groups  to  return  towards  mediocrity 
unless  Natural  Selection  interferes.  The  deduction  is  that  on 
cessation  of  selection  the  race  or  species  tends  to  remain  stable. 
But  when  we  appeal  to  reality  the  evidence  is  massive  that  cessa- 
sion  of  selection  results  in  retrogression.  Here  again  no  attempt 
is  made  to  demonstrate  that  the  Laws  of  Regression  and  Retro- 
gression are  in  accord,  or,  if  not  in  accord,  in  what  particular  the 
latter  is  wrong.  The  truth  appears  to  be  that,  though  regression 
results  in  a  levelling  up  to  the  specific  mean  as  well  as  a  levelling 
down  to  it,  yet,  in  a  degree  that  varies  in  different  species  and 
characters  according  to  the  rapidity  of  the  antecedent  progression, 
the  tendency  to  level  down  is  somewhat  greater  than  the  tendency 
to  level  up.  The  point  aimed  at  is  not  the  specific  mean,  but  below 
it.  Consequently  this  point  tends  continually  to  fall  unless 
rendered  stable  or  raised  by  selection.  Therefore  regression  is  but 
the  first  phase  of  retrogression.  As  a  rule,  however,  the  latter 
proceeds  so  slowly,  by  such  imperceptible  gradations,  that  its 
detection  is  far  beyond  the  reach  of  the  laboratory,  which  can 
examine,  at  most,  only  a  few  generations. 

226.  Formerly  some  men  of  science  maintained  that  Natural 
Selection  had  no  real  existence,  or  at  least  had  not  been  de- 
monstrated. Natural  Selection  implies  a  selective  mortality,  which 
our  acquaintance  with  the  lives  of  wild  plants  and  animals  is  not 
sufficiently  intimate  to  prove.  It  was  shown,  however,  that 
stringent  and  unmistakable  selection  occurs  amongst  all  races  of 
human  beings,  the  only  '  wild '  types  which  we  are  in  a  position  to 
observe  with  the  requisite  degree  of  thoroughness.2  In  England,  for 
example,  we  are  being  selected  by  tuberculosis  and  other  maladies ; 
in  Africa,  malaria  plays  the  same  part ;  in  India  dysentery,  and  so 
forth.  The  immediate  result  is  that  individuals  weak  against  any 
lethal  disease  are  weeded  out  wherever  it  is  present.  The  remote 
result  is  that  every  race  is  resistant  to  every  disease  in  proportion  to 
the  length  and  severity  of  its  past  experience  of  it.  Therefore  the 
evidence  of  Natural  Selection  followed  by  evolution  is  plain  and 

1  Pearson,  Grammar  of  Science  (Ed.  1900),  p.  456. 

2  See  The  Present  Evolution  of  Man,  1896.     The  common  notion  that  man  is 
not  a  '  wild  '  or  natural  type  is,  of  course,  nonsense.     He  is  not  under  the  care 
of  and  has  not  been  artificially  selected  by  any  other  type.      Civilization  has 
altered   the   conditions   under  which  he  lives,   and  therefore  the  incidence  of 
selection  and  the  direction  of  evolution,  but  that  is  all.     It  has  not  altered  the 
'  laws  '  of  heredity  for  him. 


136  RETROGRESSION 

unmistakable.  Besides  the  data  which  each  person  is  able  to  verify 
for  himself,  and  which  therefore  is  especially  valuable  scientifically 
to  him,  a  vast  volume  of  very  precise  and  detailed  statistical  infor- 
mation relating  to  almost  every  human  race  and  disease  has  been 
published  by  all  the  Departments  of  Public  Health  in  both  hemi- 
spheres. Presumably,  if  selection  followed  by  evolution  occurs 
amongst  men,  it  occurs  amongst  plants  and  lower  animals.  At 
any  rate,  if  it  occurs  amongst  men,  the  inference  that  it  occurs  and 
has  occurred  amongst  other  species  is  at  least  as  likely  to  be  true 
as  if  drawn  from  a  demonstration  of  its  occurrence  amongst  some 
other  type  of  animal  or  plant. 

227.  Such,  however,  has  been  the  passion  for  obscured  facts 
that  this  patent  evidence  has  been  ignored.     Laborious  laboratory 
inquiries  which  extended  over  several  years  have  been  undertaken 
to    demonstrate    the    actual    occurrence    of    Natural    Selection. 
Doubtless  they  satisfied  the  workers,  but  they  were  declared  by 
opponents  to  be  invalid  on  the  ground  that   natural   conditions 
were  not  accurately  reproduced.     Even  by  adherents  of  Natural 
Selection    they   are   declared  to   be    "at   present  not   absolutely 
convincing."  *     Of  all  the  statistical  evidence,  the  best  is  thought 
to  be  that  collected  by  Bumpus  in  America.2     After  a  severe  snow- 
storm one  hundred  and  thirty-six  stricken  sparrows  were  gathered, 
of  which  seventy-two  revived,  while  sixty-four  perished.     Bumpus, 
after   making   careful    measurements,    concluded    that    "  Natural 
Selection  is  most  destructive  to  those  birds  which  have  departed 
most  from  the  ideal  type,  and  its  activity  raises  the  general  standard 
of  excellence  by  favouring  those  birds  which  approach  the  structural 
ideal."     What  precisely  is  the  structural  ideal  is  of  course  a  matter 
of  opinion.     It  is  at  least  possible  that  the  birds  which  survived 
possessed  a  superior  power  of  resisting  cold  and  hardship,  and  that 
this  power  is  not  correlated  to  any  of  the  dimensions — length  of 
head,  beak,  and  so   forth — that  Bumpus   was   able   to  measure. 
Compare  the  volume,  precision,  and  relevancy  of  this  evidence  with 
that  concerning  disease  gathered  by  simple  observation,  and  more 
especially  with  that   stored   by  Departments   of  Public    Health. 
Compare  also  the  relative  difficulty  of  demonstrating  the  connec- 
tion between  cause  and  effect  in  the  two  instances. 

228.  Biometricians  have  also  sought  to  demonstrate  that  human 
mental  '  ability '  and  powers  of  resisting  disease  are  *  inheritable.' 
They  admit  that  the  human  species  has  arisen  by  evolution  from 

1  Vernon,  Variations  in  Animals  and  Plants,  p.  337. 
*  Biological  Lectures,  p.  211. 


NECESSARY  TRUTHS  137 

a  lower  type,  and  that  the  offspring  of  human  beings  are  also 
human ;  that  is  to  say,  that  human  beings  tend  to  reproduce 
parental  characteristics.  It  is  likewise  a  patent  truth  that 
man  has  more  intellectual  '  ability '  than  any  lower  animal, 
and  another  that  some  human  races,  those  that  have  suffered  most, 
are  more  resistant  to  disease  than  others.  At  least,  all  these  truths, 
however  ignored  in  the  laboratory,  are  universally  believed.  Again, 
it  is  a  patent  truth  that  a  species  or  race  is  merely  an  aggregate  of 
related  individuals,  whence  it  follows  that  if  one  generation  of  a 
species  or  race  tends  to  transmit  its  characters  to  the  next,  then 
individuals  must  tend  to  transmit  their  characters  also.  Conse- 
quently it  is  inconceivable  that  human  ability  and  powers  of 
resisting  disease  can  have  been  evolved  unless  the  paternal 
characteristics,  including  variations,  in  these  respects  tended  to  be 
inherited.  Given  the  evolution,  the  general  tendency  to  inherit 
degrees  of  capacity  is  a  necessary  corollary  which  hardly  needs 
biometric  confirmation.  Here,  as  always,  we  create  much  better 
science  when  we  deduce  one  truth  as  a  necessary  corollary  from 
another  (i.e.  when  we  link  the  two  truths  together  by  a  chain  of 
causation)  than  when  we  state  them  separately  as  isolated  facts  or 
hypotheses.1  This  unnecessary  isolation  of  hypotheses  is  a  principal 
feature  and  fault  of  nearly  all  laboratory  work.  Science  describes 
nature ;  and  nature  is  a  unity  in  which  nothing  is  isolated.  More- 
over we  have  no  means  of  estimating  the  ability  of  individuals 
except  by  noting  the  degree  of  intelligence  observable,  and,  as  we 
shall  see  later,  intelligence  depends  largely  on  mental  training,  on 
education,  which  differs  greatly  in  different  classes  and  races  and 
cannot  be  estimated  in  the  laboratory.  We  have  no  means  of 
estimating  resisting  power  to  disease  except  by  observing  the  degree 
of  resistance  displayed  under  conditions  of  food,  general  health, 
intensity  of  exposure  to  disease,  and  the  like,  all  of  which  may  vary 
with  time  and  place  and  are  also  outside  the  range  of  the 
laboratory. 

229.  Similarly  biometricians  have  sought  to  demonstrate  that 
individual  degrees  of  fertility  in  men  and  horses  tend  to  be 
transmissible.  But  how,  unless  we  presuppose  some  recent  and 
extraordinary  change  in  nature,  is  the  contrary  conceivable  ? 
Manifestly  the  relative  fertility  of  species  (groups  of  related 
individuals)  is  an  adaptation,  a  product  of  evolution,  which  could 
not  have  arisen  unless  the  variations,  the  peculiarities,  of  individuals 
had  tended  to  be  inherited  by  offspring.  The  degree  of  fertility 
1  See  §§  75  (footnote),  352  (footnote). 


138  RETROGRESSION 

differs  in  different  species,  but  always  bears  a  close  relation  to 
the  number  of  offspring  which  it  is  possible  to  rear.  Plants  and 
low  animals,  whose  characters  are  developed  wholly  or  almost 
wholly  under  the  stimulus  of  nutriment,  do  not  protect  nor  train 
their  young,  which  are  able  to  fend  for  themselves  from  the  first. 
Therefore  their  offspring  may  number  millions.  The  physical  and 
mental  characters  of  the  higher  animals  are  developed  largely 
under  the  stimulus  of  use ;  the  individual  is  born  more  or  less 
helpless,  and  must  be  protected  and  trained  during  development. 
Therefore  the  number  of  offspring  that  can  be  reared  is  very  small 
compared  to  that  in  the  lower  types.  Everywhere  we  find  an 
adaptation  as  regards  fertility  which  would  have  been  impossible 
unless  individual  peculiarities  in  fertility  had  been  transmissible 
and  had  thus  afforded  materials  for  Natural  Selection.  It  is  said 
sometimes  that,  throughout  nature,  intelligence  and  fertility  are  in 
inverse  ratio  to  each  other.  This  is  true ;  but  not  for  the  reason 
alleged — that  they  are  fundamentally  antagonistic  to  one  another. 
It  is  true  only  because  intelligence  has  to  be  trained.1  The  greater 
the  intelligence  achievable  by  an  animal,  the  more  helpless  it  is  at 
birth  and  the  more  prolonged  and  strenuous  must  be  its  preliminary 
training  by  its  parents.  Therefore,  since  intelligent  animals  are 
able  to  protect  and  train  only  a  few  offspring,  parsimonious  nature 
has  rigorously  limited  the  number  of  the  latter.  In  the  case  of 
man,  as  proved  in  the  laboratory  and  more  massively  by  Registrar- 
Generals  and  the  officials  that  correspond  to  them  in  foreign  countries, 
there  are  considerable  differences  in  fecundity  —  in  the  number 
of  offspring  actually  produced  as  distinct  from  the  number  which 
might  be  produced — between  races  and  classes.  This  may  indicate 
differences  in  fertility  ;  but  before  the  question  can  be  decided,  we 
must  pass,  as  in  the  cases  of  '  ability '  and  resisting  power  to  disease, 
outside  the  laboratory  and  inquire  into  a  multitude  of  circumstances, 
such  as  the  customs  of  the  people,  average  age  at  marriage,  religion, 
morality,  sanitation  and  general  health,  physiological  knowledge, 
desire  for  large  or  small  families,  and  the  like.  Unless  these  are 
considered,  every  deduction  concerning  human  fertility  which 
expands  an  induction  that  was  reached  through  a  statistical  con- 
sideration of  fecundity  is  illegitimate. 

230.  Numerous  biometric  studies  of  variability  have  been  pub- 
lished. In  each  case  various  characters  in  a  number  of  individuals 
(the  more  the  better)  of  the  same  race  have  been  measured  and 
the  dimensions  tabulated.  In  this  way  a  very  considerable 

1  See  §  624. 


VARIABILITY  139 

knowledge  of  the  variability  of  certain  characters  in  certain  races 
has  been  obtained — that  is,  a  knowledge  of  the  range  within  the 
limits  of  which  variations  normally  occur,  the  relative  frequency  of 
each  degree  of  deviation  from  the  mode  (the  most  common  type), 
and  the  degree  in  which  the  deviations  of  various  characters  tend 
to  be  correlated  with  one  another.  Such  knowledge  is  gathered 
only  at  great  expense  of  time  and  patience.  It  can,  as  a  rule, 
include  only  the  variations  of  the  fittest  (the  survivors),  and  never 
more  than  a  very  few  measurements  in  a  very  few  animals  and 
plants.  It  may,  of  course,  like  knowledge  of  any  other  facts,  prove 
very  useful.  But  curiously  little  effort  has  been  made  to  use  it, 
to  interpret  it,  to  link  it  up  with  laws,  with  uniformities  of  causation. 
Apparently  the  result,  such  as  it  is,  of  each  inquiry  has  been  held 
to  justify  the  labour.  As  far  as  I  am  able  to  judge,  however,  the 
biometric  evidence  concerning  variability  is  valuable  chiefly  for 
the  light  it  sheds  on,  and  the  support  it  affords  to  the  hypothesis 
that  variations  are  both  '  spontaneous '  and  under  the  control  of 
Natural  Selection.  It  demonstrates  that  variations  tend  to  occur 
about  equally  about  the  specific  mean,  the  plus  and  minus 
variations  of  every  dimension  of  a  character  being  of  nearly  equal 
frequency  and  magnitude ;  material  thus  being  afforded  which 
enables  Natural  Selection  to  meet  every  contingency.  Again, 
while  all  characters  vary,  large  variations  which  tend  to  ruin  the 
co-adaptation  of  the  parts  of  the  organism  are  rarer  than  smaller 
variations  and  most  rare  in  the  case  of  characters  in  which  the 
co-adaptation  to  the  parts  needs  to^be  very  close  ;  thus  the  squirrel's 
head  and  forefoot  vary  less  widely  in  proportion  as  regards  length 
than  the  tail.  Yet  again,  when  characters  are  functionally  corre- 
lated, the  variations  tend  to  be  correlated  also  ;  thus  if  the  length 
of  a  bone  in  a  man's  arm  is  greater  or  less  than  the  average,  it  is 
more  likely  that  the  other  bones  in  his  arm  will  be  correspondingly 
long  than  that  his  teeth,  nose,  or  beard  will  be  so.  If  the  Bathmic, 
or  the  Lamarckian  doctrine,  or  the  hypotheses  that  variations  are 
commonly  caused  by  the  direct  action  of  the  germ's  environment 
were  any  of  them  true,  variations  would  not  be  grouped  about  the 
specific  mean,  but  would  all  be  in  one  direction  or  at  least  would 
strongly  preponderate  in  it.  If  variability  were  a  '  fundamental ' 
property  of  living  beings,  uncontrollable  by  Natural  Selection,  all 
characters  should  be  equally  variable.  At  any  rate  small  variations 
should  not  so  considerably  and  universally  preponderate  in  closely, 
as  compared  to  less  closely,  co-adapted  parts.  This  last  hypothesis, 
however,  is  even  more  decisively  negatived  by  the  fact  that  the 


140  RETROGRESSION 

lengthening  of  the  germ-tract,  the  increase  in  the  number  of  cell- 
generations  which  occurs  when  plants  are  propagated  by  slips, 
does  not  result  in  an  appreciable  difference  in  the  number  and 
range  of  variations,  as  it  would  if  variability  were  a  fundamental 
character  beyond  the  control  of  natural  selection,  and  occurring, 
therefore,  all  along  the  germ-tract. 

231.  To  sum  up:  the  biometric  method,  as  employed  by  many 
of  its  exponents,  suffers  from  the  same  defect  as  the  experimental 
method.  Very  often  no  facts  other  than  those  revealed  by  a 
particular  inquiry  are  taken  into  account,  though  many  may  be 
available  ;  and,  therefore,  inferences  from  the  evidence  are  left  not 
only  isolated,  but  untested.  The  science  created  depends  alto- 
gether on  a  simple  enumeration  of  instances,  not  on  a  knowledge 
of  causes.  "  But  in  estimating  probabilities,  it  is  not  a  matter  of 
indifference  from  which  of  these  two  sources  we  derive  our 
assurance.  The  probability  of  events  as  calculated  from  their 
mere  frequency  in  past  experience  affords  a  less  secure  basis  for 
practical  guidance  than  their  probability  as  deduced  from  an 
equally  accurate  knowledge  of  the  frequency  of  occurrence  of 
their  causes."1  Not  seldom  in  biometric  inquiries — as  in  the 
case  of  those  inquiries  about  disease  and  fertility  which  we 
have  just  examined — several  scores  or  hundreds  of  observers 
and  thinkers  are  employed  for  years  in  ascertaining,  with  a 
much  lesser  degree  of  certainty,  that  which  a  single  thinker  may 
deduce  in  two  minutes  from  known  and  admitted  truths.  "  These 
are  but  samples  of  the  errors  frequently  committed  by  men  who, 
having  made  themselves  familiar  with  the  difficult  formulae  which 
algebra  affords  for  the  estimation  of  chances  under  suppositions  of 
a  complex  character,  like  better  to  employ  those  formulae  in 
computing  what  are  the  probabilities  to  a  person  half  informed 
about  a  case,  than  to  look  out  for  means  of  being  better  informed. 
Before  applying  the  doctrine  of  chances  to  any  scientific  purpose, 
the  foundation  must  be  laid  for  an  evaluation  of  the  chances,  by 
possessing  ourselves  of  the  utmost  attainable  amount  of  positive 
knowledge."  2  Experimental  observers,  whose  evidence  we  shall 
consider  next,  have  formulated  hypotheses  which  have  seemed 
fundamentally  wrong  to  biometricians.  The  latter,  or  some  of 
them,  were  induced  to  employ  their  method  mainly,  I  believe,  in 
order  to  demonstrate  the  erroneousness  of  the  conclusions  reached 
by  their  opponents.  But,  if  these  conclusions  are  mistaken,  and 
I  think  there  are  entirely  conclusive  grounds  for  believing  that 

1  Mill,  Logic,  III.  xviii.  4  2  Op.  cit.,  III.  xviii.  4. 


BIOMETRY  AND  EXPERIMENT  141 

they  are  mistaken,  the  truth  would  have  been  all  the  more 
thoroughly  proved  had  a  completer  use  been  made  of  the  biometric 
data — had  the  biometric  conclusions  (of  which  the  principal  is  the 
hypothesis  that  evolution  is  founded  on  small  variations,  '  fluctua- 
tions '  as  they  are  called,  not  on  mutations  or  sports)  been  linked 
up  with  and  tested  by  conclusions  which  are  disputed  by  nobody 
and  are  founded  on  facts,  also  undisputed,  gathered  by  simple 
observation. 


CHAPTER   VII 
MENDEL'S  LAWS 

Sexual  dimorphism — Cross-fertilization — Parthenogenesis — Self-fertilization — 
The  effect  of  conjugation — Sex  an  adaptation — Sexual  characters — Alternative 
and  blended  inheritance — Theories  of  the  function  of  sex — The  theory  of  continuous 
evolution — The  theory  of  discontinuous  evolution — The  Mendelian  theory — 
Dominance  and  recessiveness — Unit  segregation  and  gainetic  purity — Exceptions 
to  the  Mendelian  doctrine — Latency,  temporary  and  permanent — Compound 
allelomorphs — Interpretations  of  Mendelian  phenomena. 


T 


232.  f  |  ^HE  higher  animals  are  all  dimorphic,  that  is,  each 
species  is  divided  into  two  groups  which  differ  widely 
in  physical  and  mental  characters.  In  the  one  group 
are  the  males ;  in  the  other,  the  females.  Obviously,  the  sexual 
differentiation  is  connected  with  reproduction.  The  mental 
peculiarities  of  the  two  sexes  are  such  as  to  impel  to  a  series  of 
actions  which  eventually  result  in  a  union  of  sperm  with  ovum 
under  conditions  advantageous  to  the  development  of  the  future 
cell-community,  to  which  end  also  the  physical  characteristics  of 
the  parents  are  fitted.  In  all  species  the  physical  and  mental 
sexual  characters  furnish  beautiful  examples  of  co-adaptation. 

233.  Reproduction  through  the  union  of  germs  from  two  dis- 
tinct individuals  is  so  familiar  that  we  are  apt  to  accept  it  as 
*  natural '  and  so  dismiss  it  from  our  thoughts.  Conjugation,  how- 
ever, is  not  a  necessary  antecedent  of  reproduction.  Even  in  the 
higher  animals  it  occurs  only  once — when  sperm  and  ovum  con- 
jugate— during  the  production  of  the  millions  or  the  billions  of  the 
cell-community.  The  somatic  cells  never  conjugate,  and  the 
germ-cells  only  when  a  new  cell-community  is  about  to  be  pro- 
duced, and  then,  in  most  cases,  only  with  a  cell  from  another  body. 
In  the  case  of  some  plants  and  animals,  for  instance  Cypris  reptans 
reproduction  is  apparently  entirely  parthenogenetic,  no  males 
having  ever  been  observed.  Since  these  organisms  retain  their 
sexual  organs,  they  are,  of  course,  descended  from  types  in  which 
reproduction  was,  at  least,  sometimes  preceded  by  conjugation. 
In  aphides  reproduction  is  parthenogenetic  during  warm  weather 
when  food  is  plentiful,  but  the  winter  eggs  are  fertilized,  Queen 

142 


SPERMS  AND  OVA  143 

and  worker  bees  are  derived  from  fertilized,  drones  from  unfertil- 
ized eggs.  There  are  thus  gradations  between  complete  partheno- 
genesis and  conjugation  occurring  at  the  start  of  every  cell- 
community.  The  reproduction  of  unicellular  forms  has  been 
imperfectly  studied.  Possibly  in  some,  or  many,  or  most  cases 
conjugation  never  occurs.  Even  where  it  has  been  noted  there  are 
always  long  intervals  of  asexual  multiplication.  In  paramcecium, 
for  example,  at  lengthy  but  seemingly  more  or  less  fixed  intervals, 
conjugant  individuals  appear  which  differ  somewhat  from  the  rest 
of  the  population  in  appearance.  They  correspond  to  the  germ- 
cells  of  multicellular  organisms,  and  their  descendants,  which 
intervene  between  one  act  of  conjugation  and  the  next,  to  the 
generations  of  the  cell-community.1 

234.  The  ovum  is  usually  a  large  and  passive  cell,  more  or  less 
laden  with  nutriment  for  the  earliest  needs  of  the  new  cell-com- 
munity.    The  sperm  is  small  and  mobile,  and  is  thus  enabled  to 
reach  and  penetrate  the  ovum.     But,  as  already  noted,2  we  have 
every  reason  to  believe  that  these  differences  of  size,  shape,  and 
function  imply  nothing  as  far  as  the  germ-plasm  is  concerned. 
Apparently  the  germ-plasm  used  in  fertilization  is  situated  wholly, 
or  almost  wholly  in  the  nuclei  of  the  sex-cells,  and  the  nuclei  of 
sperm  and  ovum  seem  equivalent  as  bearers  of  heredity.     In  most 
cases,  conjugating  sperms  and  ova  are  derived  from  distinct  cell- 
communities  of  the  same  variety.     Conjugation  between  the  sex- 
cells  of  distinct  species,  and  in  a  lesser  degree  of  distinct  varieties, 
is  hindered  or  prevented  by  physical  or  physiological  incapacity,3 
and,  in  the  case  of  the  higher  animals,  by  mental  disinclination 
as    well.       On    the    other   hand,   nature    has    elaborated    many 
devices  to  prevent  conjugation  between  the  germs  of  the   same 
individual. 

235.  In  most  animal  species  only  sperms  or  ova  are  produced 
by  the  same  individual.     Some  low  animals,  however,  for  example 
snails   and    earth-worms,   and    many   plants   are   hermaphrodite, 
possessing  male  and  female  organs  of  generation,  and  producing 
both  sperms  and  ova.     In  such  cases,  self-fertilization  is  prevented 
by  the  ripening  of  the  sperms  and  ova  at  different  periods,  or  in 
other  ways.     The  prevention  is  usually  less  perfect  in  the  case  of 
plants  than  of  animals,  so  that  in  the  former  case  self-fertiliza- 

1  See  §  i.  2  See  §  2. 

3  Physical  disability  prevents,  for  example,  a  very  large  dog  mating  with  a 
very  small  one.  Physiological  disability  renders  mating  sterile.  In  the  latter 
case  the  sperms  do  not  fertilize  the  ova,  or,  as  is  probable  in  some  cases,  the 
embryos  do  not  develop  beyond  a  very  early  stage. 


144  MENDEL'S  LAWS 

tion  may  more  often  alternate  with  cross-fertilization.  Some 
plants,  and  some  plant-like  marine  animals  are  normally  self- 
fertilized.1  Thus  there  are  connecting  links  between  constant 
cross-  and  constant  self-fertilization. 

236.  The  normal  effect  of  conjugation,  then,  is  to  mix,  with 
a  degree  of  intimacy  which  is  in  dispute,  two  germ-plasms  which 
on  the  whole  resemble  one  another  somewhat  closely,  but  which 
differ  in  details.     The  difference  is  greatest  when  individuals  of 
different  species  cross,  and  least  when  there  is  self-fertilization. 
Indeed,    self-fertilization  is   an   approach   to   parthenogenesis   in 
which  there  is  no  mixture.     Another  approach  is  the  alternation 
of  parthenogenesis  with  conjugation  as  in  aphides.     Plainly,  then, 
conjugation  is  not  an  essential  part  of  reproduction,  which  may 
and  does  occur  without  it.     Indeed  it  is  precisely  the  partheno- 
genetic  types  that  reproduce  most  rapidly.     But  it  is  an  accom- 
paniment of  reproduction  so  nearly  universal  that  we  have  reason 
to  believe  that  it  must  possess  some  extremely  important  function. 
Presumably  it  is  an  adaptation  which,  like  other  adaptations,  has 
been  created  and  maintained  by  Natural  Selection — an  adaptation 
so  vastly  useful  that,  to  attain  it,  most  multicellular  species  have 
become  dimorphic  and  have  evolved  all  the  manifold  physical  and 
mental  peculiarities  of  sex,  including  the  keenest  and  fiercest  of 
instincts,  so   useful    that   to   possess   it   the   possible  number  of 
offspring  has  been  halved,  since  two  individuals  instead  of  one 
are  necessary  to  the  production  of  each  child.2     Thus  great  advan- 
tages are  lost  for  the  sake  of  what  is  probably  a  greater. 

237.  The  function  of  sex  (of  conjugation,   of  the  mixing  of 
germ-plasms)  has  been,  especially  of  recent  years,  one  of  the  most 
widely  and  acrimoniously  debated  of  all  the  problems  of  heredity. 
Too  often  in  these  discussions  has  the  great  probability  that  sex 
is  an  adaptation,  and,  therefore,  like  other  adaptations,  a  product 
of  Natural  Selection,  been  ignored.     Sex  is  so  widespread  and  is 
served  by  so  many  and  such  diverse  physical  and  mental  characters, 
that  to  doubt  that  it  has  utility,  to  suppose  it  is  a  mere  chance 
accompaniment  of  life,  is  the  very  madness  of  scepticism.       No 
theory  of  sex  is  likely  to  be  true  that  assigns  to  it  a  non-adaptive 
function.     What,  then,  is  the  function  of  sex  ?     In  what  way  is  it 
useful?     How  does  it  serve  to  adapt  species  to  their  environ- 
ments ?     Moreover,  how  is  it  that  some  types  are  cross-fertilized, 
others  self-fertilized,  and  others  parthenogenetic,  while  yet  others 
exhibit    gradations    between    cross-fertilization,    occurring    regu- 

1  Origin  of  Species,  p.  123.  2  See  §  336. 


INHERITANCE  AND  REPRODUCTION  145 

larly   at    the    genesis    of    every   cell-community,    and    complete 
parthenogenesis  ? 

238.  Before  we  attempt  to  solve  the  problem  of  sex  we  must 
study  for  a  space  the  phenomena  of '  inheritance.'     When  repro- 
duction is  parthenogenetic,  offspring  reproduce  parental  characters 
with  variations.     When  two  parents  are  concerned  in  reproduction 
the  process  is  more  complicated.     In  sexually  dimorphic  species 
the  two  parents  resemble  one  another  closely  in  some  particulars, 
for  example  in  blood,  muscles,  glands,  heart,  lungs,  liver,  nerves, 
and  the  like.     In  others,  the  sexual  characters,  they  differ  much 
more  widely.     The  child,  being  male  or  female,  develops  only  one 
set  of  the   sexual   characters.      The  other  set,   however,  is  not 
wholly  absent.     Its  items  are  merely  rudimentary  or  latent.     The 
male  breasts  in  man  are  examples  of  rudimentary  organs.     Of 
latency  there  is  unlimited  evidence :    for  example,   female  birds 
have   been   known    in  old   age  to  develop   the   plumage   of  the 
opposite  sex ;  elderly  women  occasionally  develop  to  some  extent 
beards  and  moustaches ;  haemophilia  and  colour-blindness,  which 
are  usually  male  characters,  are  transmitted  through  daughters  to 
grandsons,  and  the  good  milking  qualities  of  cows  through  sons  to 
granddaughters ;   the    female   characters   of  bees  are   apparently 
transmitted  through  the  drones,  and  the  male  characters  through 
the   queens  ;    doubtless,    however,    both    sets   of    characters    are 
transmitted  through  both  sexes.     The  male  characters  of  aphides 
are  transmitted  through  a  long  series  of  pathenogenetic  females. 
This  form  of  reproduction,  in  which  one  only  of  two  possible 
characters,     or    sets     of    characters,    is     developed,    is     termed 
1  alternative.' 

239.  The  development  (not  inheritance,  for  both  sets  are 
'  inherited  ' )  of  the  sexual  characters,  then,  is  alternative.  But  the 
term  '  sexual '  must  be  given  a  wide  meaning.  It  applies  not  only 
to  those  primary  differences  of  shape  and  function  which  are 
directly  concerned  in  reproduction,  but  also  to  those  secondary 
peculiarities  of  shape,  colour,  scent,  and  the  like  which,  being 
mostly  on  the  surface  of  the  body,  and  therefore  observable,  serve 
as  sexual  attractions,  as  well  as  to  the  other  physical  and  mental 
peculiarities  which  distinguish  the  sexes.  Most  of  the  sexual 
characters  tend  to  hang  together  in  sets,  a  male  set  and  a  female 
set ;  but  some  characters,  which  are  sexual  in  the  sense  that  their 
function,  in  whole  or  part,  is  to  attract  the  opposite  sex,  occur  in  both 
sexes  ;  for  example  in  human  beings  the  mane  on  the  scalp  and  the 
coloration  of  the  hair,  skin,  and  eyes.  But  even  in  the  case  of  those 
10 


146  MENDEL'S  LAWS 

characters  which  are  common  to  both  sexes  and  which  may  have 
other  functions  besides  sexual  attraction,  development  tends  to  be 
alternative.  Thus  the  child  of  parents,  one  of  whom  has  blue  eyes 
and  the  other  hazel,  usually  has  blue  eyes  or  hazel  eyes,  never  eyes 
that  are  a  blend  between  blue  and  hazel.  So  too,  in  a  lesser  degree, 
children  sometimes  reproduce  the  colour  and  texture  of  hair  of 
one  parent,  and  to  a  still  lesser  degree  the  colour  of  the  skin. 

240.  Obviously   the   alternative    development    of    the   sexual 
characters  is  an  adaptation,  a  product  of  evolution.     It  is  a  device 
by   which    cross-fertilization    is   secured.     Though   evolution   has 
caused  most  of  the  sexual  characters  to  hang  together  in  sets,  yet 
the  separation  of  male  and  female  characters  is  not  always  strictly 
preserved.     Occasionally  a  character,   usually  distinctive   of  one 
sex,  is  found  in  an  individual  of  the  opposite  sex.     Thus,  a  man 
may  possess  well-developed   female   breasts,  or  a  woman   a  full 
beard.     Sometimes  the  male  and  female  characters  may  be  found  so 
intermixed,  as  for  example  in  the  so-called  human  hermaphrodites,1 
that  an  individual  of  one  sex  may  present  every  external  appear- 
ance of  belonging  to  the  other.     Or  the  male  and  female  characters, 
instead  of  being   inherited   alternatively,  may  blend  in   varying 
degrees — as  when  a  woman  is  partially  bearded  or  has  a  mascu- 
line pelvis. 

241.  Selection,  natural  and  sexual,  however,  must  always  have 
tended  to  eliminate  these  abnormalities  and  so  preserve  the  purity 
of  the  sexual  characters,  their  alternative  development,  and  their 
aggregation  in  distinct  sets.     Selection  is,  of  course,  more  stringent 
as  regards  the  primary  sexual   characters,  which   are   the    more 
essential  part  of  the  machinery  of  reproduction,  than  as  regards 
the  secondary  characters.     Consequently  blending  or  displacement 
from  the  set  in  which  they  are  normally  found  is  rarer  in  the  case 
of  the  former  than  the  latter.  Thus  men  may  have  female  breasts  and 
women  beards,  but  never,  as  far  as  I  am  aware,  have  testes  been 
found  associated  with  a  uterus.     By  artificial  selection  man  has 
more  than  once  succeeded  in  transferring  secondary  sexual  char- 
acters from  one  sex  to  the  other.     Thus  formerly  only  the  female 
Polish  fowl  had  the  domed  skull  and  cerebral  hernia  which  now 
characterizes  both  sexes,2  and  the  male  Sebright  bantam  has  the 

1  A  real  hermaphrodite  is  an  individual  in  whom  both  sets  of  sexual  characters, 
the  male  and  the  female,  are  patent ;  for  example,  snails  and  most  flowering 
plants.  A  '  so-called  '  hermaphrodite  is  an  individual  in  whom  the  male  and 
female  characters  have  blended,  or  one  in  whom  some  male  and  some  female 
characters  are  patent. 

1  Animals  and  Plants,  vol.  i.  p.  269. 


THE  FUNCTION  OF  CONJUGATION  147 

same  hackles,  saddle,  and  stickle  feathers  as  the  female.     "  Conse- 
quently the  tail  is  short  and  truncate  as  in  a  hen." 

242.  Manifestly  the  differentiation  and  the  alternative  develop- 
ment of  the  sexual  characters  is  not  in  itself  an  end.     A  male  has 
patent  one  set  of  characters  and  a  female  another,  and  males  and 
females  are  reproduced  alternatively,  not  because  the  individual  is 
thereby  brought  into  closer  adaptation  to  the  general  environment 
and  his  or  her  life  more  surely  preserved,  but  to  afford  facilities  for 
mixing  the  germ-plasm,  a  process  which,  for  some  reason,  we  have 
yet  to  discuss    and  if  possible   discover  is  of  advantage  to   the 
species.     Therefore  it  is  likely  that  the  sexual  characters   have 
come  into  existence  because  the  non-sexual  characters  are,  in  some 
way,    beneficially   affected   by   the   intermixture  of  the   parental 
germ-plasms.     When,  therefore,  we  have  discovered  how  the  non- 
sexual  traits  are  thus  usefully  affected  by  conjugation,  we   shall 
have  discovered  the  function  of  sex. 

243.  Formerly,  because,  in  the  higher  animals,  young  individuals 
come  into  existence  only  after  acts  of  conjugation,  the  'obvious 
inference'   was  drawn  that  the  function   of  sex  is  to  invigorate, 
revitalize,  or  rejuvenate  aged  and  debilitated  germ-plasms.     But, 
as  indicated  by  Weismann,  it  is  difficult  to  understand  how  the 
union  of  two  outworn  and  enfeebled  things  can  result  in  rejuve- 
nescence.    Moreover,  parthenogenetic  species,  and  plants  which  are 
propagated  by  slips,  retain  their  vitality  perfectly. 

244.  Next  Weismann,  followed  by  the  majority  of  biologists, 
believed  that  the  special  function  of  the  intermixture  of  somewhat 
dissimilar  germ-plasms  which  occurs  in  conjugation  is  to  provide 
the   spontaneous   variations   which   are   the   materials   on  which 
Natural     Selection    works,      He    concluded     consequently    that 
parthenogenetic  species  vary  little  if  at  all,  and,  therefore,  are 
incapable  of  adapting  themselves  to  changes  in  the  environment. 
He  supposed  that   they  secured  survival,  not  by  close  adaptation 
but  only  by  a  very  rapid  rate  of  reproduction.     But  rapid  repro- 
duction is  an  adaptation  which  can  have  arisen  only  through  the 
Natural  Selection  of  favourable  variations.     Therefore  variations 
must  have  occurred  even  after  conjugation  was  abandoned.    Besides, 
it   has  been   proved  directly  that  he  was  mistaken.     Variations 
occur  in  abundance  when  reproduction  is  parthenogenetic.     Thus 
Weismann   himself   discovered    evidence   of  variations  occurring 
in   the   absence   of  sexual   reproduction,1  and   as   a   result   of  a 
biometric    inquiry   conducted    on    the   parthenogenetic   Daphnia 

1  The  Germ-Plasm,  Eng.  Trans.,  pp.  344-6. 


148  MENDEL'S  LAWS 

magna^  Dr  E.  Warren  found  "  on  measuring  the  offspring  it  was 
obvious  that  the  children  of  the  same  brood  exhibited  considerable 
variability." 1  A  more  extended  inquiry  on  Aphides  led  him  to 
suppose,  however,  that  variability  in  asexual  reproduction,  though 
considerable,  is  less  than  when  offspring  have  two  parents.  We 
shall  see  that  this  relative  paucity  of  variations  is  due,  probably, 
to  a  comparative  lack  of  retrogressive  variations.  Lastly,  it  is  a 
well-established  fact  that  parthenogenetic  species,  for  example 
dandelions  and  hawkweeds,  are  particularly  rich  in  varieties,  a  fact 
implying  abundant  variations.2 

245.  Variability,  then,  can  occur  apart  from  conjugation.  We 
saw  that  the  evidence  is  strong  that  spontaneous  variability  is  an 
adaptation  controlled  and  maintained  by  Natural  Selection,  on 
which  account  every  species  and  organ  tends  to  be  variable  in  the 
right  degree.3  The  least  variable  types  and  structures  are  those 
which  are  closely  adapted  to  the  environment  by  stringent  selection. 
The  more  variable  types  and  structures  are  those  which  are  less 
closely  adapted  and  in  which  therefore  variability  is  encouraged  by 
Natural  Selection,  or  those  which  are  not  stringently  selected  for 
the  reason  that  very  close  adaptation  is  not  necessary.  Thus  men 
and  garden  plants  are  exceptionally  variable  because  they  are  so 
circumstanced  that  individuals  that  have  varied  largely,  for 
example  in  colour,  have  survived  in  considerable  numbers  and 
have  transmitted  their  increased  variability  to  descendants.  Thus 
again  the  squirrel's  tail  is  more  variable  than  its  head  and  forefoot 
because  there  is  a  greater  need  for  close  adaptation  in  the  latter. 
Since,  then,  spontaneous  variations  occur  in  parthenogenetic 
reproduction,  the  materials  are  present  for  the  work  of  Natural 
Selection,  and  that  agency  is  able  to  increase  or  decrease  the 
variability  of  the  species  to  any  useful  extent.  Bi-parental  repro- 
duction is  not  necessary  for  the  purpose ;  and  it  is,  at  the  very 
least,  most  improbable  that  species  can  have  been  burdened  with 
sex  to  produce  that  which  was  already  present,  and  which, 
apparently,  is  kept  within  bounds  only  by  selection.  Undoubtedly, 

1  Proc.  Roy.  Soc.  London,  1899,  vol.  Ixii.  p.  154. 

*  See  De  Vries,  Species  and  Varieties,  pp.  59-61.  "  Thousands  of  forms  (of 
dandelion  and  hawkweed)  may  be  cultivated  side  by  side  in  the  Botanical  Gardens 
and  exhibit  slight  but  undoubted  differentiating  features,  and  reproduce  them- 
selves truly."  I  follow  De  Vries  in  supposing  that  dandelions  and  hawkweeds 
are  parthenogenetic.  I  know  nothing  of  the  matter  personally.  There  seems, 
however,  to  be  some  doubt  (see  Bateson,  Mendel's  Principles  of  Heredity,  p.  247). 
At  any  rate  it  appears  clear  that  these  plants,  if  they  do  conjugate,  do  so  com- 
paratively rarely. 

3  See  §  163. 


ALTERNATION  AND  BLENDING  149 

therefore,  Professer  Karl  Pearson  is  right  in  declaring  that  "  Varia- 
bility is  not  a  product  of  bi-parental  inheritance ;  .  .  .  whatever  be 
the  physiological  function  of  sex  in  evolution,  it  is  not  the 
production  of  greater  variability." l 

246.  At  the  present  day  I  think  most  biologists   who  have 
given  any  thought  to  the  question  believe  that  the  function  of  sex 
is   (through   the   mixing   of  germ-plasms)   to   mix   the  parental 
qualities.     There  are,  however,  great  differences  of  opinion  as  to  the 
nature  and  effect  of  this  mixing.     Suppose  a  man  with  black  eyes 
and  six  digits  on  each  hand  mates  with  a  woman  with  blue  eyes 
and  the  normal  number  of  digits  ;  then  experience  demonstrates  that 
each  of  the  descendants  of  such  a  pair  will  have  black  eyes  or  blue 
eyes  (or  perhaps  grey  or  hazel  eyes,  as  in  some  ancestor)  :  never, 
or  hardly  ever,  eyes  that  are  intermediate ;  and  six  digits  or  five 
digits,  not  five  and  a  half  digits.     But  one  or  more  of  the  children 
may  develop  the  father's  eyes  in  combination  with  the  mother's 
hands,  or  the  mother's  eyes  with  the  father's  hands.     In  such  a 
child  the  parental  characters  are  mixed  ;  but  they  are  mixed  as 
black  and  blue  marbles  in  a  bag,  not  as  black  and  blue  colours 
are  blended  on  a  painter's  palate.     On  the  other  hand,  the  offspring 
of  a  white  man  and  a  negress  actually  does  blend  the  parental  skin 
colours  ;  the  descendants  are  not  black  or  white,  but  of  a  colour 
that  is  more  or  less  intermediate. 

247.  Here,  then,  we  have  two  distinct  types  of  '  inheritance,'  the 
alternative  and  the  blended,  both  of  which  undoubtedly  occur. 
Since  in  the  first  type  the  father's  or  the  mother's   character  is 
reproduced,  not  a  blend,  and  since  the  grandchild  may  have  patent 
the  character  which  was  latent  in  the  parents,  the  resemblance  to 
the  method  by  which  the  sexual  characters  are  *  transmitted '  is 
evident,  the  main  difference  being  due  to  the  fact  that  whereas  the 
various  sexual  characters  tend  strongly  to  hang  together  in  distinct 
patent  or  latent  sets,  the  non-sexual  characters,  the  reproduction 
of  which  is  alternative,  tend  to  mix  and  so  form  new  combinations. 
Now  the  question  we  shall  have  to  decide  is  whether  the  function 

1  Grammar  of  Science,  pp.  473-4,  ed.  1900.  In  my  Work,  The  Principles  of 
Heredity  (p.  49),  I  controverted  Professor  Pearson's  statement,  and  pointed  out 
that  a  mulatto,  for  instance,  the  offspring  of  a  white  man  and  black  woman, 
varies  from  both  parents  in  a  definite  way.  I  must  now  confess  that  I  seem 
to  have  mistaken  Pearson's  meaning.  Conjugation  is  certainly  a  cause  of  some 
variations,  in  that  the  offspring  when  they  blend  parental  characters  vary  from 
both; parents.  But  variations  and  variability  are  different  things.  A  partheno- 
genetic  species  may  be  as  variable  or  more  variable  than  one  the  reproduction 
of  which  is  bi-parental. 


ISO  MENDEL'S  LAWS 

of  sex  is  to  mix  non-sexual  parental  characters  as  colours  are 
blended,  or  to  mix  them  as  marbles  are  mixed.  What,  then,  is  the 
rule  in  nature?  Is  blended  'inheritance'  the  normal  for  non- 
sexual  characters  and  alternative  *  inheritance '  abnormal  ?  Or  is 
alternative  *  inheritance '  the  normal  ?  Or  are  they  both  normal  in 
the  sense  that  nature  has  evolved  both  as  adaptations — in  the 
sense  that  both  have  utility  ?  This  question  is  being  very  sharply 
debated  at  the  present  time.  Formerly  it  was  universally  believed 
— by  Darwin  for  example — that  offspring  tend,  as  a  rule,  to  blend 
parental  characters,  and  this  view  is  now  upheld  by  most  biologists, 
and  in  particular  by  the  biometric  or  statistical  school.  The 
experimental  or  *  Mendelian '  school,  on  the  other  hand,  insist 
that  the  non-sexual  characters  of  parents  are,  as  a  rule,  not  blended 
in  offspring.1 

248.  Naturally  these  divergent  views  of  heredity  have  led  to, 
or   are    associated    with,   equally   divergent    views   of    evolution. 
Speaking   generally,    biometricians   maintain   that   variation   and 
evolution  are  both  continuous ;  in  other  words,  they  suppose  that 
nature  causes  evolution  by  gradually  and  continuously  raising  the 
specific  mean  through  the  selection  of  '  normal '  or  '  fluctuating ' 
variations. 

249.  On  the  other  hand,  experimental  workers,  who  are  usually 
'  Mendelians '  and  '  Mutationists,'  insist  that  there  are  two  distinct 
kinds  of  variations,  the  continuous  and  the  discontinuous.     The 
former,  they  maintain,  fluctuate  about  a  mean  to  which  they  tend 
to  return  so  strongly  in  succeeding  generations,  that  they  cannot 
be  made  the  foundation  of  permanent  racial  divergence  by  any 
stringency  of  selection.     In  other  words,  they  suppose  that,  owing 

1  It  is  interesting  to  note  how  the  different  methods  by  which  the  rival  schools 
pursue  their  inquiries  have  tended  to  lead  to  divergent  theories  of  heredity. 
We  shall  see  presently  that  blended  '  inheritance  '  is  the  rule  when  parents  differ 
comparatively  little,  that  is,  when  their  differences  are  of  degree  rather  than 
of  kind  ;  and  that  alternative  '  inheritance  '  is  the  rule  when  parental  differences 
are  greater,  that  is  when  they  are  of  kind  rather  than  of  degree.  The  statis- 
tician dealing  with  aggregates  of  individuals,  and  noting  that  even  when  parental 
differences  are  great,  offspring  tend  to  '  regress  '  towards  the  parental  and  specific 
mean,  is  impressed  by  the  fact  that  extreme  plus  and  minus  deviations  from  the 
average  type  of  the  race  are  rare  and  are  connected  by  lesser  variations.  He  is 
inclined,  therefore,  to  lay  stress  on  the  truth  that  the  vast  majority  of  variations 
are  '  continuous,'  and  to  believe  that  offspring  tend,  as  a  rule,  to  blend  parental 
characters.  The  experimental  worker,  on  the  other  hand,  deals  with  individuals 
more  than  with  aggregates,  and  naturally  chooses  as  materials  for  study  sharply 
contrasted  parental  qualities,  the  inheritance  of  which  can  be  more  easily  observed 
in  offspring  than  mere  shades  of  difference.  He  tends,  therefore,  to  lay  stress  on 
'  discontinuous  '  variations,  and  to  believe  that  alternative  inheritance  is  the  rule. 


FLUCTUATIONS  AND  MUTATIONS  151 

to  the  tendency  to  reversion,  or  rather  regression,  these  fluctuating 
variations  cannot  be  accentuated  or  piled  on  one  another  by 
selection  continued  through  any  number  of  generations.  Accord- 
ing to  them  evolution  is  founded  solely  on  discontinuous  variations 
('  mutations '),  which,  though  they  may  not  always  differ  from  con- 
tinuous variations  in  magnitude,  yet  differ  totally  in  kind  and  in 
that  they  are  absolutely  stable.1  It  is  thought  that,  if  an  individual 
in  whom  one  of  these  discontinuous  variations  appears  has  mated 
with  an  individual  who  has  it  not,  then  a  proportion  of  the 
descendants  inherit  it  and  a  proportion  do  not ;  there  is  rarely  a 
blend.  If  it  is  unfavourable,  the  descendants  that  are  of  the  new 
type  are  eliminated,  and  it  disappears  from  the  race ;  if  it  is 
favourable,  the  ancestral  type  may  be  eliminated  in  the  struggle  for 
existence  and  the  new  type  established  in  its  place  ;  if  the  variation 
is  neither  favourable  nor  unfavourable,  the  two  types  exist  side  by 
side.  According  to  the  Mendelian  and  mutationist  view,  therefore, 
evolution  does  not  proceed  continuously  (along  a  smooth  incline, 
as  it  were),  but  by  a  series  of  steps  of  varying  but  usually  con- 
siderable magnitude.  The  theory  of  evolution  by  discontinuous 
variations  finds  its  strongest  advocate  in  Professor  Hugo  de  Vries, 
the  distinguished  Dutch  botanist.  His  opinions  differ,  however,  in 
some  very  important  particulars  from  those  of  the  more  extreme 
Mendelians.2 

250.  The   theory   of  continuous  evolution    (that    is,  evolution 
founded  on  ordinary  '  fluctuating '  variations)  is  sometimes  termed 
the  *  selection '  theory,  that  of  discontinuous  evolution  the  *  muta- 
tion '  theory.     Both  theories,  however,  are  doctrines  of  evolution 
by  the  selection  of  favourable  variations.     They  differ  in  that  they 
attribute  evolution  to  the  piling  up  of  different  classes  of  variations. 
It  is  true,  however,  that  mutationists  often  lay  much  less  stress 
on  selection  and  adaptation  than  selectionists. 

251.  Sir  Francis  Galton,  who  may  be  said  to  have  founded  the 
biometric  school,   distinguishes    three    kinds    of  inheritance:    (i) 
Particulate,  or  inheritance  "  bit  by  bit,  this  element^from  one  pro- 
genitor that  from  another,"  3  as  when  black  and  white  poultry  are 
crossed  and  the  offspring  have  in  varying  degrees  some  feathers 
black   or   barred,   and    others   white.      (2)   Exclusive,    when    the 
character  of  only  one  parent  is  reproduced  to  the  total  exclusion 
of  the  other,  as  when  the  plumage  of  the  offspring  of  black  and 

1  Doubtless  the  opinion  that  discontinuous  variations  are  absolutely  stable 
is  not  held  by  all  mutationists.  Apparently,  however,  it  is  held  by  many  of 
them.  See  §  285. 

*  See  §  282.  3  Natural  Inheritance,  p.  7. 


152  MENDEL'S  LAWS 

white  fowls  is  wholly  black  or  wholly  white.  Particulate  inherit- 
ance may  be  regarded  as  exclusive  inheritance  occurring  in  patches. 
(3)  Blended  inheritance,  as  in  the  skin  colour  of  a  mulatto. 
Blended  inheritance  i  may  be  regarded  as  particulate  inheritance 
occurring  in  a  very  fine  mosaic.  Galton  thinks,  "  There  are  pro- 
bably no  heritages  that  perfectly  blend  or  that  absolutely  exclude 
one  another,  but  all  heritages  have  a  tendency  in  one  or  the  other 
direction,  and  the  tendency  is  often  a  strong  one." l  There  can  be 
no  doubt,  however,  that  small  progressive  variations  (fluctuations) 
present  in  one  parent,  but  absent  in  the  other,  tend  to  disappear 
absolutely  in  the  offspring.  In  such  cases,  therefore,  there  is  no 
blending.2 

252.  The  greater  part  of  modern  experimental  work  follows 
the  lines  laid  down  by  Gregor  Mendel,  a  monk  who  became  Abbot 
of  Briinn,  and  who  about  the  middle  of  the  last  century  crossed 
many   varieties   of  the   edible    pea — Pisum   sativum.      Peas   are 
normally  self-fertilized,  the  pollen-grains  and  ovules  of  the  same 
flower  uniting.     But  the  plants  have  conspicuous  flowers,  which, 
presumably,  underwent  evolution  because  they  attracted  insects 
and  so  secured  cross-fertilization.    We  must  suppose,  therefore,  that 
peas  have  descended  from  ancestors  that  interbred.     If  the  anthers 
of  a  flower  be  amputated  before  the  pollen  is  ripe,  and  pollen  from 
another  plant  be  conveyed  to  the  pistil,  it  is  still  possible  to  secure 
cross-fertilization. 

253.  Mendel  worked  with  a  number   of  strongly  contrasted 
varieties — 'tall'   and    'dwarf    plants,    for    example.      From   the 
mongrel  seeds,  thus  obtained,  only  tall  plants  developed.     They 
were  allowed  to  self-fertilize  themselves,  as  were  their  descendants. 
About   one-quarter   of  the   offspring — the   grandchildren   of  the 
original  cross — developed  as  dwarfs  and  three-quarters  as  tall  plants. 
No  plants  were  intermediate.     Thereafter  the  dwarfs  continued  to 
breed  '  true '  as  long  as  the  experiments  were  continued,  producing 
no  tall  plants  in  succeeding  generations.     It  seemed  evident  that 
the  race  was  purged  of  the  influence  of  the  tall  variety.     On  the 
average,  a  similar  number  of  tall  plants  behaved  in  like  manner, 
producing  only  tall  descendants.     Their  race,  also,  had  become 
'  pure.'     But  the   remaining  plants  (fifty  per  cent,  of  the  whole) 
behaved  like  their  cross-bred  parents,  producing  tall  and  dwarf 
offspring  in  the  old  proportion,  the  dwarfs  being  all  pure,  and  the 
tall  plants  pure  and  impure.     This  process,  also,  continued  until 
the  experiments  ceased. 

I0p.  cit,,p.  iz.  8See  §  194. 


DOMINANTS  AND  RECESSIVES  153 

254.  Mendel  supposed  that  the  'tall 'and  'dwarf  characters 
were  represented  by  units  in  the  substance  we  now  call  germ- 
plasm.     He  thought  that  each  pollen  grain  and  unfertilized  ovule 
(gamete,  or  germ-cell)  contained  one  unit  for  stature,  and  therefore 
that  each  fertilized  ovule  (zygote)  contained   two.1     One  only  of 
these  units  directed  development,  and  the  character  which  resulted 
from  its  influence  he  termed  the  *  dominant.'     The  latent  character 
was  termed  the  '  recessive.' 

255.  He  supposed  further  that  before  the  development  of  the 
germ-cells  of  the  mongrel  plant  which  sprang  from  the  zygote,  the 
units  multiplied  and  separated,  so  that  in  each  of  its  pollen  grains 
and  ovules  only  one  unit  was  present,  a  dominant  unit  or  a  reces- 
sive unit.     When  the  plant  flowered  and  self-fertilization  again 
took  place,  it  was  a  matter  of  chance  whether  these  units  paired 
with  their  own  kind  in  the  zygote,  or  with  units  of  the  opposite 
type.     If  a  dominant  unit  met  another  dominant  the  result  was  a 
'pure  '  dominant  plant,  which  never  had,  nor  could  have  a  recessive 
descendant  so  long  as  self-fertilization  continued.     In  like  manner, 
if  a  recessive  unit  met  another  recessive  the  line  became  exclusively 
recessive.     But,  if  a  dominant  met  a  recessive,  the  resulting  plant 
was  an  l  impure*  dominant,  which  looked  like  the  pure  dominant,  but 
was  really  different  in  that  it  was  a  hybrid  having  descendants  of 
the  three  types,  pure  dominants,  recessives,  and  impure  dominants. 
Every  plant  which  displayed  the  recessive  character  was  pure  of 
course,  for  otherwise  the  dominant  element  would  have  been  patent. 

256.  If  the  reader  will   shake  together  in   a   bag   a   hundred 
black  and  a  hundred  white  buttons,  representing  dominant  and 
recessive  units  respectively,  and  then  withdraw  them  at  hazard  in 
pairs,  he  will  find  that,  on  the  average,  half  the  buttons  will  be 
paired  with  their  own  kind  and  half  with  the  opposite  kind.     He 
will  then  have  approximately  twenty-five  black  pairs  representing 
pure  dominants,  twenty  -  five  white  pairs  representing  recessives, 
and  fifty  black-and-white  pairs   representing  impure   dominants. 
The  proportion  of  pure  dominants,  recessives,  and  impure  domi- 
nants, therefore,  is  supposed  to  be  regulated  by  the  law  of  chance. 

257.  It   was    found   that   peas   possessed    several    Mendelian 
characters  besides  length  of  stem,  for  example  colour  of  cotyle- 
dons (yellow  or  green),  colour  of  seed  skins  (brownish  or  white), 
colour  of  flowers  (purple  or  white),  shape  of  ripe  pods(  inflated  or 
constricted),  colour  of  unripe  pods  (green  or  yellow),  position  of 
flowers  (axial  or  terminal),  and  shape  of  seeds  (round  or  wrinkled). 

1    See  Bateson,  Mendel's  Principles  of  Heredity,  pp.  338-9. 


154  MENDEL'S  LAWS 

One  of  each  of  these  characters  is  always  dominant  over  its 
alternative,  for  example  yellow  in  the  cotyledons  is  dominant  over 
green,  purple  in  flowers  over  white,  round  shape  over  wrinkled 
shape  in  seeds. 

258.  But,  if  a  variety  has  one  character  which  is  dominant  over 
its  alternative  in  another  variety,  it  does  not  follow  that  the  rest 
of  its  characters  are  also  dominant     One  or  more  characters  in  the 
second  variety  may  be  dominant.     Consequently,  if  two  varieties 
are  crossed,  the  first  mongrel  generation  (all  impure  dominants]  may 
exhibit  some  of  the  characters  of  one  variety  and  some  of  the  other. 

259.  Moreover,  if  a  variety  having  a  certain  set  of  Mendelian 
characters  is  crossed  with  a  variety  having  another  set,  then  the 
descendants  are  apt  to  exhibit  the  characters  in  new  combinations 
even   after  they   have   become  c  pure.'     Thus,   if  a  variety   with 
inflated    pods,  wrinkled  seeds,  and  green  cotyledons  be  crossed 
with    one    having    constricted    pods,    round    seeds,    and    yellow 
cotyledons,  the  '  pure  '  descendants  may  exhibit  every  combination 
of  the  alternative  characters,  for  example  contracted  pods  with 
round  seeds  and  yellow  cotyledons,  or  inflated  pods  with  wrinkled 
seeds  and  yellow  cotyledons.     It  appears,  therefore,  that  unlike 
sexual  characters,  the  alternative  or  Mendelian  characters  do  not 
necessarily  hang  together  in  sets,  but  are  '  inherited '  independently 
of  one  another.     When,  therefore,  we  study  heredity  in  terms  of 
the  Mendelian  theory,  we  must  think,  as  always,  not  of  the  in- 
dividual as  a  whole,  but  of  his  characters  separately.     Obviously, 
the  hypothesis  that  characters  are  represented  in  the  germ-plasm 
by   units,  which  pair  in  the  fertilized  ovum  but  separate  in  its 
germinal  descendants,  is  an  inference,  not  an  observed  fact.     These 
units  cannot  be  seen  in  the  germ-plasm,  or,  if  seen,  recognized. 
It  is  this  inference  which  is  especially  the  Mendelian  hypothesis 
and  on  which  stress  is  laid.1 

260.  The  points   to  be   especially  noted   when    studying   the 
Mendelian  theory  are  (i)  the  alternative  units  are  supposed  not  to 
blend  or  unite  in  the  fertilized  ovum  (zygote)  with  their  *  opposite 
numbers,'  but  to  remain  distinct  and  ultimately  to  segregate,  so  that 
the  gerrn-cells  (gametes)  of  the  individual  that  arises  from  the 
zygote  contain  each  only  one  unit  for  each  character ;  hence  the 
terms  '  unit  segregation  '  and  '  gametic  purity.'     (2)  The  different 

1  "  This  purity  of  the  germ-cells  and  their  inability  to  transmit  both  of  the 
antagonistic  characters  is  the  central  fact  proved  by  Mendel's  work;  We  thus 
reach  the  conception  of  unit  characters  existing  in  antagonistic  pairs."  (First 
Report  to  the  Evolution  Committee  of  the  Royal  Society,  by  Miss  Sanders  and  Mr 
Bateson,  p.  126,  1902.) 


QUALIFICATIONS  OF  MENDEL'S  LAWS  155 

units  of  a  set  are  supposed  not  to  hang  together  but  to  be  inherited 
independently  of  one  another  so  that  new  combinations  may  be 
formed.  They  have  been  termed  *  allelomorphs/  alternative 
inheritable  units,  each  of  which  in  one  set  of  allelomorphs  is 
capable  of  displacing  its  opposite  number  in  another  set.  (3)  One 
unit  of  every  pair  tends  to  be  dominant  over  its  alternative,  so 
that  when  both  are  present  in  a  zygote  the  individual  which  springs 
from  it  displays  the  dominant  character  only.  Such,  at  any  rate, 
were  the  chief  points  of  the  Mendelian  theory  as  originally  pro- 
pounded, and  as  held  very  recently. 

261.  More  extended   study,  however,  has  rendered  it  evident 
that  in  all  points  the  Mendelian  doctrine  needs  more  or  less  qualifica- 
tion.    Dominance  is  seldom  if  ever  complete.     As  regards  any 
Mendelian  character,  the  hybrids  of  the  first  generation  (all  impure 
dominants)  usually  resemble  the  dominant  parent  more  nearly  than 
the  recessive  ;  but  the  influence  of  the  latter  may  be  observed,  at 
least  very  often.     "  Even  in  the  pea  it  is  not  the  case  that  the 
heterozygote  [mongrel]  always  shows  the  dominant  allelomorph  as 
clearly  and  in  the  same  intensity  as  the  pure  dominant,  and,  speak- 
ing generally  heterozygotes,  though  in  numerous  instances  readily 
referable  to  one  or  other  of  the  allelomorphic  types,  exhibit  these 
types  in  a  more  or  less  modified  form."1     Frequently  indeed  a 
combination  of  parental  qualities  amounting  to  particulate,  mosaic, 
or  even  blended   inheritance  is  observable  in  offspring.     Thus  a 
cross  between  black  and  white  plumage  in  poultry  may  result  in 
barred  offspring,  as  often  happens  when  the  white  Leghorn  fowl 
is  crossed  with  the  black  Cochin  ; 2  or  in  a  minute  patchwork,  as 
in  the  case  of  the  blue  Andalusian  fowl  which  results  from  crossing 
a  black  bird  with  a  '  splashed '  white ;  or  there  may  be  complete 
blending,  as  in  the  offspring  of  a  white  man  and  negress.3 

262.  Sometimes     the    usually    recessive     character     may    be 
dominant.4     Again,  instead  of  one  type  being  dominant  over  the 
other,  the  character  of  neither  parent  is  reproduced,  but  a  common 
ancestral  form    reappears.     For  example,  when  albino  mice  are 
crossed   with   black-and-white   Japanese  waltzing  mice   "a   grey 

1  First  Report  to  Evolution  Committee,  p.  129. 

2  Davenport,  Inheritance  in  Poultry,  p.  40. 

3  Adherents  of  the   Mendelian  doctrine   sometimes   maintain   that  blended 
inheritance  is  nothing  other  than  a  fine  mosaic.     Doubtless  they  are  right ;   but 
I  imagine  their  opponents  mean  nothing  more  by  blended  inheritance  than  that 
it  is  a  very  fine  mosaic — a  mosaic  as  fine,  perhaps,  as  the  mixture  of  colours  in  a 
painter's  brush.     All  blending,  for  example  a  mixture  of  alcohol  and  water,  is  a 
mosaic,  even  if  one  of  chemical  molecules. 

4  First  Report  to  Evolution  Committee,  p.  120, 


156  MENDEL'S  LAWS 

house-mouse  resembling  in  size,  colour,  and  wildness  the  wild 
house-mouse  " 1  is  produced  ;  when  yellow-grey  Belgian  rabbits  are 
crossed  with  white  (albino)  Angoras  the  offspring  have  "  wild-grey 
coats  indistinguishable  from  those  of  the  wild-grey."  2  When  Mr 
Hurst  crossed  Black  Hamburgh  with  Buff  Cochin  poultry,  "in  the 
first  plumage  the  two  sexes  are  quite  distinct.  The  cockerels  had 
golden-brown  hackles,  red-brown  saddles,  black  and  brown  tails  and 
wings,  and  buff-brown  breasts  regularly  spangled  with  black.  The 
pullets  were  as  dull  and  sober  in  colour  as  the  cockerels  were 
brilliant,  being  black  intermixed  with  light  and  dark  brown,  with 
darker  tails  and  heads  and  spangled  breasts.  It  seems  rather 
curious  that  a  cross  between  two  breeds,  each  of  which  has  normally 
similar  plumage  in  both  sexes,  should  produce  offspring  in 
which  the  two  sexes  are  so  distinctly  differentiated."3  Among 
domesticated  pigeons  the  plumage  of  the  wild  blue-rock,  and 
among  poultry  that  of  the  ancestral  Gallus  bankiva  may  reappear 
when  domesticated  breeds  are  crossed.  When  the  horse  is  crossed 
with  the  Burchell  zebra,  which  has  a  few  broad  stripes,  the  offspring 
present  the  narrower  and  more  numerous  stripes  of  a  remote 
ancestor.4  Similar  instances  of  'reversion'  are  common  amongst 
plants  ;  for  example,  if  a  jonquil  be  crossed  with  a  daffodil,  Narcissus 
odorus  results.5 

263.  Dominance  may  be  influenced  by  the  environment,  as  in 
the    case   of    Ewart's   pigeons,   whose  offspring   reproduced   the 
characters  of  the  English  parent  when  the  Indian  parent  was  ill, 
but  those  of  the  latter  when  its  health  was  good.6 

264.  Dominance   may  be  affected  by  the  sex  of  the   parent. 
Thus,  when  white  Leghorn  and  Indian  Game  poultry  are  crossed, 
"  all  male  cross-breds  and  female  cross-breds  from  Indian  Game 
mother  almost  always  have  the  ground  colour  white,  but  female 
cross-breds  from  white  Leghorn  mothers  have  the  ground  colour 
more  or  less  dingy-brownish  white." 7     "  Booting  (feathered  foot)  is 
always  dominant  when  the  feathered  form  is  the  mother,  no  matter 
what  the  race."  8     "  The  canary  has  two  forms  which  are  both  in  a 
sense  albino,  the  yellow  and  the  cinnamon.     When  green  (viz.  non- 

1  Fust  Report  to  Evolution  Committee,  p.  145. 

2  C.  C.  Hurst,  Experimental  Studies  on  Heredity  in  Rabbits,  p.  301. 

3  Second  Report  to  Evolution  Committee,  p.  135. 

4  Ewart,  The  Penicuick  Experiments,  p.  92. 

5  Vernon,  Variations  in  Animals  and  Plants,  p.  169. 

6  See  §  132. 

7  First  Report  of  Evolution  Committee,  p.  99. 

8  Davenport,  Inheritance  in  Poultry,  p.  86. 


GAMETIC  PURITY  157 

albino)  females  are  crossed  with  cinnamon  males,  both  greens  and 
cinnamons  are  invariably  female.  When  cinnamon  females  are 
crossed  with  green  males  the  young  are  always  green."1  The 
instance  "  most  familiar  amongst  animals  is  perhaps  that  of  the 
Mule  (Mare  and  Jackass)  and  the  Hinny  (She-ass  and  Stallion) 
and  amongst  plants  the  hybrids  of  Digitalis."  2 

265.  Dominance  may  be  influenced  by  race.     "  While  long  tail 
and  crest  feathers  are  dominant  in  poultry,  long  hair  (equally  due 
to  the  prolonged  life  of  the  follicle)  is  recessive  in  mammals  (Castle, 
1903,    1905;    pp.   64-7,  73-4;    Hurst,    1904).      White   is   usually 
recessive   to   pigment   in   flowers   and    mammals,  but   is   usually 
dominant  to  pigment  in  poultry."  3    "  Yellow  (beak  and  foot  colour) 
of  the  white  Leghorn  dominates  over  black  of  the  Minorca,  but 
yellow  of  the  dark  Brahma  is  dominated  by  the  Minorca."  4 

266.  Dominance  may  be  affected  by  the  idiosyncrasies  of  the 
parent.     "  In  all  cases  as  yet  investigated  (in  poultry)  individuals 
differ  greatly  in  the  results  they  give,  and  we  can  only  suppose  that 
these  differences  represent  different  proportions  in  the  number  of 
effective  dominant  and  recessive  germs  which  they  produce."  5 

267.  Lastly,  in  some  cases  it  is  difficult  to  say  which  of  a  pair 
of  characters  is  dominant,  since  both  are  patent  in  about  equal 
numbers  in  the  first  mongrel  generation,  as  in  the  case  of  a  sixth 
digit  in  man  or  a  fifth  toe  in  poultry.     Even  when  a  character  is 
usually  strongly  dominant  over  its  alternative,  recessive  individuals 
sometimes  appear  in  the  first  mongrel  generation.6 

268.  To  sum  up :    it   is  very  evident  that  "  Dominance   is   a 
matter  of  degree,  not  of  kind  ;  " 7  "  Dominance  is  a  phenomenon 
presenting  various  degrees  of  intensity."  8 

269.  We  have  next  to  consider  the  hypothesis  of  gametic  purity 
— a  hypothesis  which  implies  that  the  pure  dominants  and  recessives 
which  spring  from  impure  dominants  of  the  first  and  succeeding 
mongrel  generations,  extracted  pure  dominants  and  recessives  as 
they  are  called,  inherit  only  one  kind  of  unit  out  of  each  pair  of 
alternative  units,  and  therefore  (as  regards  each  separate  character) 
are  in  effect  derived  from  only  one  of  the  crossed  ancestral  lines. 

1  Second  Report  to  Evolution  Committee,  p.  128. 
z  First  Report  to  Evolution  Committee,  p.  132. 

3  Davenport,  Inheritance  in  Poultry,  p.  132. 

4  Ibid.,  p.  87- 

5  First  Report  to  Evolution  Committee,  p.  106. 

8  First  Report  to  Evolution  Committee,  pp.  119  et  seq. 

7  Inheritance  in  Poultry,  p.  85. 

8  First  Report  to  Evolution  Committee,  p.  126. 


158  MENDEL'S  LAWS 

In  order  to  understand  the  ensuing  discussion  with  ease  the  reader 
is  advised  to  familiarize  himself  with  the  following  :  (i)  According 
to  the  Mendelian  hypothesis  from  a  cross-bred  individual,  if  self- 
fertilized  or  mated  with  another  impure  dominant,  should  arise 
pure  dominants,  recessives,  and  impure  dominants  in  the  average 
proportion  of  one  pure  dominant  and  one  recessive  to  two  impure 
dominants,  this  proportion  being  due  to  the  circumstance  that  the 
dominant  and  recessive  units  should  be  present  in  the  germ-cells  of 
the  cross-bred  in  about  equal  numbers.  If  the  three  kinds  of 
offspring  depart  much  from  the  stated  proportions,  it  is  evident  that 
something  besides  pure  chance  is  at  work.  The  impure  dominants 
of  the  next  and  succeeding  generations  should  behave  in  a  similar 
manner.  (2)  Since  an  impure  dominant  produces  an  equal  number 
of  dominant  and  recessive  gametes,  therefore,  if  such  an  individual 
of  any  generation  be  crossed  with  a  pure  dominant  (which  produces 
only  dominant  gametes),  half  the  offspring,  on  the  average,  should 
be  pure,  and  half  impure  dominants.  If  crossed  with  a  recessive 
half  the  offspring  should  be  impure  dominants  and  half  recessives. 
(3)  Pure  extracted  dominants,  mated  together,  should  produce  only 
pure  dominants,  extracted  recessives  only  recessives,  and  extracted 
recessives  crossed  with  pure  extracted  dominants  only  impure 
dominants  in  the  first  cross.  (4)  With  respect  to  each  separate 
character,  then,  pure  extracted  dominants  and  recessives  are  not, 
from  the  Mendelian  point  of  view,  hybrids  at  all ;  they  are  believed 
to  be  gametically  pure,  having  reverted  wholly  to  one  or  other  of 
the  types  that  were  crossed,  the  other  type  being  quite  eliminated 
from  them.  They  should  exhibit,  therefore,  no  tincture  of  the 
alternative  characters. 

270.  In  all  points,  however,  the  doctrine  of  unit  segregation  and 
gametic  purity  needs  qualification.  Thus,  when  Mendel  crossed 
round  with  wrinkled  peas,  he  obtained  in  the  second  mongrel 
generation — when  the  proportion  of  dominants  (pure  and  impure) 
to  recessives  should  have  been  as  three  to  one — in  one  case  forty- 
three  dominants  to  two  recessives,  and  in  another  fourteen  domi- 
nants to  fifteen  recessives  ;  and,  when  he  crossed  yellow  with  green 
peas,  he  got  in  one  case  twenty  dominants  to  nineteen  recessives, 
and  in  another  thirty-two  dominants  to  one  recessive.1  In  some 
cases  extracted  recessives  (presumably  pure)  when  crossed  with 
pure  recessives  gave  dominant  offspring  instead  of  only  recessives. 
In  one  such  case  ninety-four  dominants  and  a  single  recessive 
resulted.2  In  other  cases  only  pure  dominants  producing  only 

1  First  Report  to  Evolution  Committee,  p.  128.  a  Op.  cit.}  p.  79. 


PATENCY  AND  LATENCY  159 

pure  dominant  offspring  resulted  in  the  first  hybrid  generation.1 
Millardet's  '  false  hybrids '  are  celebrated.  He  "  found  that  when 
certain  varieties,  especially  of  strawberry,  are  crossed  together, 
(i)  the  cross-breds  may  precisely  reproduce  the  maternal  type, 
without  any  indication  of  the  paternal  characters  ;  (2)  in  other  cases 
the  cross-bred  individuals  may  show  either  the  maternal  characters 
pure  (save  in  one  case  the  colour  of  fruits)  or  the  paternal  characters 
pure.  Seeds  from  plants  thus  exclusively  reproducing  one  parental 
type  themselves  gave  plants  again  exclusively  of  that  type.  To 
such  forms  he  gives  the  name  'faux  hydrides'  or  ' hydrides  sans 
croisement!  "  2  Other  similar  cases  might  be  mentioned.3 

271.  All    these   facts    are    inconsistent  with    the    Mendelian 
doctrine.     For  example,  if  unit  segregation  and  gametic  purity  are 
realities,  how  is  it  possible  (i)  that  only  pure  dominants,  having 
only  dominant  descendants,  can  occur  in  the  first  hybrid  genera- 
tion, or  (2)  that  recessives  can  ever  produce  dominant  offspring  and 
descendants  ?     We  may  indeed  adopt  the  far-fetched  hypothesis 
that  in  the  first  case  recessive  units  or  gametes  were  not  produced, 
or  perished,  leaving  only  dominants  to  continue  the  race,  and  in 
the  second  the  more  probable  conjecture  that  the  recessives  were 
in  reality  impure  dominants  in   which   the   recessive   units   had 
temporarily  become  dominants. 

272.  But  another    explanation    not  only   inherently   more  pro- 
bable,   but    supported    by     evidence     that    appears     massive     and 
conclusive,    is   possible.       We    saw    that    the    development,    not 
inheritance,   of   the   sexual   characters   is   alternative.     In    every 
individual,  for  example  man  or  woman,  one  of  each  pair  of  sexual 
characters  is  as  a  rule  entirely  dominant  over  its  alternative.     The 
alternative,    however,    is   present   in    a   latent   condition,    that   is 
every  individual  is  an  impure  dominant.     Thus,  in  man  bearded- 
face  is  dominant  over  smooth-face,  whereas  the  latter  is  dominant 
in  a  woman  ;  but  the  man  transmits  the  latent  female  character  to 
his  daughters  and  the   woman  the  latent  male  character  to  her 
sons.     Here  the  inheritance,  so-called,  is  alternative  in  a  completer 
sense  than  in  the  case  of  Mendelian  characters  ;  for  each  character 
is  in  turn  dominant  over  its  alternative.     But  in  some  cases  male 
characters  may  become  latent  for  prolonged  periods,  as  in  aphides 
during  the  summer.     Female  characters  are  seemingly,  permanently 
recessive  in  the  ova  of  the  queen  bee,  for  unfertilized  eggs  produce 

1  Op.  cit.,  p.  80.  *  Op.  cit.,  p.  154. 

*Op.cit.,p.  8 1.     See  also  Bateson,  Mendel's  Principles  of  Heredity,  chapter 


160  MENDEL'S  LAWS 

only  drones  ;  while,  presumably,  male  characters  are  permanently 
latent  in  such  species  as  propagate  only  by  parthenogenesis. 

273.  Now  the  presumption  is  that  the  inheritance  of  the  Men- 
delian  characters  is  of  the  same  type  as  that  of  the  sexual  characters, 
and  therefore  that,  instead  of  segregation  and  gametic  purity,  what 
really  occurs  is  patency  and  latency}-  If  that  be  the  case  the 
recessive  character,  which  is  temporarily  latent  in  the  *  impure ' 
dominant,  is  permanently  latent  in  a  line  of  *  pure '  dominants, 
whereas,  on  the  other  hand,  the  dominant  is  permanently  latent  in 
the  recessives — permanently  latent,  that  is,  until  the  conditions 
which  bring  about  such  latency  are  disturbed  in  much  the  same 
way  as  when  the  conditions  of  latency  of  the  female  characters  in 
the  ova  of  the  bee  are  disturbed  by  fertilization,  or  those  which 
bring  about  the  latency  of  the  male  characters  in  the  summer  ova 
of  aphides  are  disturbed  by  the  advent  of  winter.  If  this  be  true, 
the  independent  inheritance  of  characters  on  which  Mendelians 
insist  is  a  myth.  There  is  only  independent  development,  inde- 
pendent patency  and  latency.  When,  therefore,  one  variety  is 
crossed  with  another  and  the  descendants  show  the  varietal 
characters  in  new  combinations,  all  the  alternative  characters  of 
both  varieties  are  present,  but  only  a  half  of  them  are  patent,  and 
this  half  includes  characters  from  both  species. 

274.  Evidence  more  direct  than  that  furnished  by  analogy  is 
not  lacking.  Contrary  to  what  was  formerly  believed,  the  { ex- 
tracted '  pure  dominants  and  recessives  of  the  second  and  succeeding 
generations  are  rarely  without  traces  of  the  alternative  characters. 
They  are  in  truth  real  mongrels  (not  only  as  regards  the  whole 
individual,  but  as  regards  each  separate  character)  in  which  one  or 
more  of  the  characters  of  one  of  the  crossed  varieties  predominates 
more  or  less,  the  degree  of  this  predominance  varying  from  an 
absolute,  or  almost  absolute  completeness  that  approaches  the 
commonly  complete  dominance  of  the  sexual  characters,  to  a 
blend  intermediate  between  the  crossed  varieties.  Thus  in  the 
case  of  poultry,  "  very  frequently,  if  not  always,  the  character  that 
has  once  been  crossed  has  been  affected  by  its  opposite  with  which 
it  was  mated  and  whose  place  it  has  taken  in  the  hybrid.  It  may 
be  extracted,  therefrom,  to  use  in  a  new  combination,  but  it  will  be 
found  altered.  This  we  have  seen  to  be  true  for  almost  every 
character  sufficiently  studied — for  the  comb  form,  the  nostril  form, 

1 1  made  this  suggestion  in  the  second  edition  of  The  Principles  of  Heredity 
(Appendix  B) ;  I  find,  however,  I  was  anticipated  by  Professor  T.  H.  Morgan 
(Science,  xxii.,  1905). 


COMPOUND  ALLELOMORPHS  161 

cerebral  hernia,  crest,  muff,  tail  length,  vulture  hock,  foot-feathering, 
foot-colour,  earlobe,  and  both  general  and  special  plumage  colour. 
Everywhere  unit  characters  are  changed  by  hybridizing."  1  Clearly, 
then,  as  is  sometimes  the  case  with  the  sexual  characters,  especially 
the  less  stringently  selected  secondary  sexual  characters  (e.g.  in 
human  'hermaphrodites'),  the  allelomorph,  which  is  supposed  by 
Mendelians  to  be  absent,  very  often,  indeed  almost  always  makes 
its  presence  felt.  We  must  assume,  therefore,  that  before  separat- 
ing— if  they  do  separate — the  alternative  units — if  there  are  any 
units — infect  one  another  (i.e.  blend)  so  as  to  form  hybrid  units ;  or 
else  we  must  assume  that  they  do  not  blend,  but  remain  together, 
and  that  one  (but  not  always  the  same  one)  dominates  more  or 
less  completely  over  the  other.  In  any  case,  "  construed  in  the 
strictest  sense  the  doctrine  of  gametic  purity  is  untenable."2 

275.  Now  ample  evidence  exists  that  allelomorphs  sometimes 
combine  to  form  compound  allelomorphs.  When  two  varieties 
are  crossed,  one  or  other  form  may  dominate,  or  the  type  may 
blend,  or  the  ancestral  type  may  appear.  When  this,  the  first 
mongrel  generation,  is  self-fertilized  or  bred  together,  it  sometimes 
happens  that  there  is  no  return  in  the  offspring  to  the  grandparents 
(the  types  that  were  crossed).  On  the  contrary  the  descendants 
break  up  into  two  or  more  forms  distinct  from  the  grandparents, 
one  or  more  of  which  may  breed  true.  For  example,  if  the  Stanley 
sweet-pea,  which  has  dark  maroon  petals  (standards  and  wings), 
be  crossed  with  the  Giant  White,  the  offspring  are  Giant  Purple 
Invincibles  with  maroon  standards  and  blue  wings.  "  These  first- 
crosses,  self-fertilized,  gave  Giant  White,  Giant  Purple  (without 
blue  wings),  Mars  (a  well-known  red  variety),  Her  Majesty  (a  full 
magenta,  well-known),  and  a  form  like  Her  Majesty,  but  flaked 
with  white.  One  plant  of  each  was  saved  and  its  self-fertilized  seed 
sown.  Mars  and  Her  Majesty  came  true.  The  Giant  White  was 
tested,  and  it  came  true  also.  The  Her  Majesty  flaked  with  white, 
however,  gave  Whites,  Her  Majesty,  and  Her  Majesty  flaked  white 
again.  The  Giant  Purple  gave  Giant  White,  Her  Majesty,  Giant 
Purples,  and  two  plants  of  a  streaky  cream  colour.  .  .  .  We  are 
then  led  to  the  conclusion  that  the  allelomorph  transmitting  the 
coloration  of  Stanley  is  compound,  and  that  it  can  be  broken  up 
into  simpler  and  possibly  component  elements."  3 

1  Inheritance  in  Poultry,  p.  80. 

2  Castle  and  Allen,  The  Heredity  of  Albinism.     Proceedings  of  the  American 
Academy  of  Arts  and  Sciences,  vol.  xxxviii.  No.  21,  p.  615. 

3  First  Report  to  Evolution  Committee,  pp.  142-3.     See  also  Bateson,  Mendel's 
Principles  of  Heredity,  pp.  60  et  seq. 

II 


1 62  MENDEL'S  LAWS 

276.  It    is    admitted,    then,    that    two    or    more    dissimilar 
allelomorphs    sometimes  unite   permanently   to    form    compound 
allelomorphs  which  are  transmitted  to  descendants  as  units.     In 
the  case  quoted  above,  the  component  characters  are,  I  believe, 
supposed   to   have   been  more  or   less  patent,  and   therefore  the 
Stanley  presented  an  appearance  different  from  any  of  the  types 
from  which  it  was  obtained  by  cross-breeding.     But,  if  compound 
allelomorphs  in  which  each  component  unit  is  patent  may  occur, 
it   is   not  unreasonable   to  suppose  that  allelomorphs,  supposing 
they  exist,  may  sometimes  combine  to  form  more  or  less  permanent 
compounds  in  which  one  (or  more)  of  the  components  is  patent 
and   the  other   (or   others)   latent.     That   this   has  happened   at 
least  very  frequently  there  can  be  no  possible  doubt.     We  see  it 
in  aphides,  in  which  the  allelomorphs  for  the  male  characters  are 
latent  all  the  summer.     Every  case  of  the  reappearance  of  a  latent 
ancestral  character  (at  any  rate  in  a  pure-bred  race) l  is  an  instance 
of  it. 

277.  If  we  cross   a  Japanese  waltzing  mouse  with  an  albino 
mouse,  then  the  ancestral  wild-grey  colour  reappears  in  a  large 
proportion  of  the  offspring.     It  is  supposed,  doubtless  correctly,  by 
Mendelians,  that  the  special  characters  of  the  two  domestic  breeds 
arose  originally  as  mutations  from  the  wild  type.     Since  it  is  very 
improbable  that  two  animals  varied  discontinuously  in  the  same 
way  and  at  the  same  time  and  place,  the  mutants  (as  the  individuals 
that  underwent  mutation  are  termed)  were  crossed  with  the  wild 
type.2     The  reproduction  was  Mendelian,  and  artificial  selection 
established  a  race  of  *  pure '  recessives  amongst  the  descendants 
— Japanese  waltzing  mice  in  the  one  case  and  albinos  in  the  other. 
According   to   the    Mendelian    doctrine   of  unit  segregation  and 
gametic  purity  the  grey   colour  should  have  been    quite  absent 
(not   latent)  from  both  varieties.3     It  was  only  latent,  however. 
It  follows  that  in  this  case   there  was  no  unit  segregation    nor 
gametic  purity.     What  really  occurred  was,  not  the   elimination 
of  the   '  grey   allelomorph '    but   the   formation    of  a   compound 

1  See  §  280. 

2  "  Mendel's  discovery,  it  will  be  understood,  applies  only  to  the  manner  of  trans- 
mission of  a  character  already  existing.     It  makes  no  suggestion  as  to  the  manner 
in  which  such  a  character  came  into  existence.     The  facts,  however,  leave  no  room 
for  doubt  that  at  least  one  character  of  each  pair  of  simple  allelomorphs  has  arisen 
discontinuously.     The  fact  that  the  gametes  of  the  cross  transmit  each  member 
of  the  pair  pure,  is  as  strong  an  indication  as  can  be  desired  of  the  discontinuity 
between  them."     First  Report  to  Evolution  Committee,  p.  151.     See  §  290. 

3  See  §255. 


LATENT  ANCESTRAL  CHARACTERS  163 

allelomorph  in  which  the  grey  was  permanently  latent.  It 
would  appear,  therefore,  that  the  essential  features  of  Mendelian 
inheritance  are,  not  segregration  and  gametic  purity,  but  the  perma- 
nent dominance  of  one  alternative  character  and  the  permanent  latency 
of  the  other. 

278.  Any  number  of  similar  instances  might  be  quoted.     Thus 
when    Mr    A.    D.    Darbishire   crossed    fawn-and-white   Japanese 
waltzing  mice  v/ith  albinos,  the  descendants  exhibited  a  number 
of  colours  which  he  classified  as  yellow,  fawn  colour,  grey  (pale 
and  dark,  the  colours  of  the  wild  mouse),  black,  lilac  (pale  and  blue- 
grey),  and  chocolate.1     In  this  as   in   many  other  instances  (e.g. 
Stanley  sweet-pea,  quoted  above)  the  allelomorphs  from  both  the 
crossed  varieties  were  evidently  highly  compound,  several  latent 
characters  being  revealed.     The  appearance  of  the  black  coloration 
is  particularly  interesting.     It  has  appeared  also  when  pigmented 
guinea-pigs   and  rabbits   were    crossed   with   an    albino   variety. 
Thus  Mr  C.  C.  Hurst  crossed  Belgian  rabbits  which  have  yellow- 
grey  fur   with   angoras  which  are  albinos.2     Both   varieties   had 
been  pure-bred  for  at  least  eight  and  probably  many  more  genera- 
tions.    The  offspring  all  displayed  "  grey  coats  like  that  of  the 
common    wild   rabbit."     Bred    together   the   mongrels   produced 
wild    greys,    albinos,    Dutch-marked,    and    black   offspring.     The 
three   latter  types   bred  true  when  mated  with   their  own  kind. 
They   were   pure   recessives.     The  greys  were  pure  and  impure 
dominants,  with  albino,  black,  or  Dutch  markings  as   the  latent 
element.     There  was  never  a  return  to  the  yellow-grey  Belgian 
coloration.      A    further   series    of  experiments    proved    that   the 
black  coloration  as  well  as   the  grey  and   Dutch    markings  had 
been  introduced  by  the  various  albinos  of  the  original  cross.     Now 
albinism  is  a  typical  recessive  character  which,  according  to  the 
doctrine  of  unit  segregration,  should  always  be  pure.     Yet  we  see 
that  in  mice,  rabbits,  and  guinea-pigs  it  may  be  associated  with 
latent  grey,  black,  or  Dutch  coloration.     Plants  furnish  evidence 
similar  in  kind,  and  even  greater  in  quantity.     Thus  if  two  white- 
flowered  varieties  of  garden  plants  be  crossed  the  offspring  may 
have  coloured  flowers. 

279.  The   reproduction    of  ancestral    traits    seems   to    afford 
evidence  that  is  decisive  in  favour  of  the  hypothesis  of  alternate 

1  "  On  the  Result  of  Crossing  Japanese  Waltzing  with  Albino  Mice"  Biometrika, 
Jan.  1904. 

*"  Experimental  Studies  on  Heredity"  Linnean  Society's  Journal,  Zoology, 
vol.  xxix. 


1 64  MENDEL'S  LAWS 

latency  and  patency,  and  fatal  to  the  hypothesis  of  segregation. 
Nevertheless,  Professor  Cuenot  has  attempted  to  surmount  the 
difficulty.1  He  supposes  that  colour  depends,  not  on  a  single 
unit  or  hereditary  tendency,  but  on  two,  a  colour  factor  and  a 
colour  determiner.  According  to  him,  if  the  one  or  the  other  be 
absent,  the  individual  is  an  albino.  As  a  fact,  it  is  the  factor 
that  is  supposed  to  be  absent  from  the  albino,  which,  it  appears, 
usually  carries  one  determiner  and  may  carry  more.  According 
to  the  latest  views  the  factor  is  always  the  same  for  all  the  colours 
of  a  species,  but  the  determiners  (which  Bateson  has  surmised 
are  ferments  2)  may  be  as  many  as  there  are  differently  coloured 
varieties.3  Colours  (i.e.  ferments)  vary  in  dominance,  the  ancestral 
colour,  for  example  '  wild-grey  '  in  rabbits  and  mice,  often  being  the 
most  dominant  of  all.  Consequently,  if  an  albino  rabbit  or  mouse 
be  crossed  with  some  coloured  domestic  variety  (e.g.  Belgian 
rabbit  or  Japanese  waltzing  mouse),  then,  since  the  albino  races 
seem  always  to  carry  the  grey  determiner,  and  the  coloured  variety 
carries  the  factor,  the  offspring  are  all  grey.  If  more  determiners 
are  carried  by  the  albino,  the  descendants  are  not  only  grey  and 
white,  but  other  colours  as  well.  In  this  way  the  reappearance 
of  ancestral  traits  when  varieties  are  crossed  is  accounted  for  in 
terms,  not  of  latency,  but  of  segregation. 

280.  Cuenot's  hypothesis  of  factors  and  determiners  has  been 
used  to  interpret,  not  only  the  reproduction  of  ancestral  colours  but 
also  that  of  all  other  ancestral  peculiarities,  for  example  shape  and 
instinct.  Presumably  these,  also,  are  due  to  ferments.  But,  since 
both  Cuenot's  hypothesis  and  the  hypothesis  of  segregation,  which 
it  is  intended  to  support,  are  merely  founded  on,  not  tested  by 
experiment,  the  repetition  of  the  explanation  in  any  number  of 
instances  does  not  prove  them  to  be  true.  Apparently,  however, 
mere  repetition  is  all  their  adherents  consider  necessary.  The  facts 
fit  the  hypothesis  of  simple  latency  and  patency  at  least  equally  well. 
Indeed  they  fit  the  latter  better  ;  for,  if  we  hold  it,  we  have  no  ex- 
ceptions, such  as  those  I  have  summarized  in  paragraphs  271  and 
284,  to  explain  away.  Here  then  we  have  two  rival  hypotheses, 
two  interpretations  of  the  same  facts.  Both  of  them  remain  simple 
guesses,  utterly  valueless  to  science,  unless  they  can  be  tested.  "  In 
such  a  case  it  is  necessary  to  look  for  some  instance  which  can  be 

1  La  loi  de  Mendel  et  V  hdrdditi  de  la  pigmentation  chez  les  souris  (2me  note). 
Arch,  de  ZooL,  exp.  et  gen  (4),  Notes  et  revue,  pp.  xxxiii.-xli. 

1  Mendel's  Principles  of  Heredity,  pp.  226-9. 

3  The  Progress  of  Genetics  since  the  Rediscovery  of  Mendel's  Papers,  by  W. 
Bateson. 


CRUCIAL  INSTANCES  165 

explained  on  one  only  of  these  rival  hypotheses ;  .  .  .  such  a  test 
case  is  called  a  Crucial  Instance" *  "  One  single  circumstance, 
which  admits  of  one  explanation  only,  is  more  decisive  than  a 
hundred  others  which  agree  in  all  points  with  one's  own  hypo- 
thesis, but  are  equally  well  explained  on  an  opposite  hypothesis."  2 
Now,  as  regards  the  rival  hypotheses  of  segregation  and  latency, 
any  number  of  cases  have  been  recorded  which  furnish  quite 
decisive  crucial  instances  ;  but,  though  the  experimental  school 
has  piled  one  untested  interpretation  on  another,  though  they  have 
explained  alternative  reproduction  by  segregation,  segregation  by 
factors  and  determiners,  and  determiners  by  ferments,  never  yet 
has  any  appeal  been  made  to  them.  Ancestral  traits  may  be 
awakened  experimentally  by  crossing  domesticated  varieties ;  but 
these  are  not  the  only  occasions  when  they  appear.  Their  reproduc- 
tion by  pure-bred  individuals  is  far  from  uncommon.  "Thus  we 
see  that,  in  purely  bred  races  [of  pigeons]  of  every  kind  known  in 
Europe,  blue  birds  occasionally  appear  having  all  the  marks  which 
characterize  C.  livia" 3  The  following  is  a  very  striking  instance 
of  the  reappearance  of  long  latent  ancestral  characters  in  an 
individual  which  not  only  reproduced  them,  but  had  previously 
reproduced  those  of  her  own  variety  as  well.  Several  like  instances 
have  been  recorded.  "  Mr  Hewitt  possessed  an  excellent  Sebright 
gold-laced  bantam  hen,  which,  as  she  became  old,  grew  diseased  in 
her  ovaria,  and  assumed  male  characters.  In  this  breed  the  males 
resemble  females  in  all  respects  except  in  their  combs,  wattles, 
spurs,  and  instincts ;  hence  it  might  have  been  expected  that  the 
diseased  hen  would  have  assumed  only  those  masculine  characters 
which  are  proper  to  the  breed ;  but  she  acquired,  in  addition,  well- 
arched  tail  sickle-feathers  quite  a  foot  in  length,  saddle-feathers  on 
the  loins,  and  hackles  on  the  neck — ornaments  which,  as  Mr  Hewitt 
remarks,  '  would  be  held  as  abominable  in  this  breed.'  The 
Sebright  bantam  is  known  to  have  originated  about  the  year  1800 
from  a  cross  between  a  common  bantam  and  a  Polish  fowl, 
recrossed  by  a  hen-tailed  bantam,  and  carefully  selected ;  hence 
there  can  hardly  be  a  doubt  that  the  sickle  feathers  and  hackles 
which  appeared  in  the  old  hen  were  derived  from  the  Polish  fowl 
or  common  bantam  ;  and  we  thus  see  that  not  only  certain  masculine 
characters  proper  to  the  Sebright  bantam,  but  other  masculine 
characters  derived  from  the  first  progenitors  of  the  breed,  removed 

Welton,  Manual  of  Logic,  vol.  ii.  p.  102. 
Ueberweg,  Logic,  Eng.  Trans.,  p.  513. 
Animals  and  Plants,  vol.  i.  p.  206. 


166  MENDEL'S  LAWS 

by  a  period  of  above  sixty  years,  were  lying  latent  in  this  hen-bird, 
ready  to  be  evolved  as  soon  as  her  ovaria  became  diseased." l 
Here  there  can  have  occurred  no  reunion  of  previously  divorced 
factors  and  determiners.  The  only  conceivable  interpretation  of  the 
facts  is  that  the  ancestral  characters  were  latent',  and  if  they  are 
latent  in  the  pure-bred  varieties,  we  have  no  right  to  assume  that 
they  segregate  in  the  mongrel.  "  Entia  non  sunt  multiplicanda 
pr&ter  necessitatem" 

281.  Very  obviously  Cue"not  and  his  followers  have  not  taken 
all  the  evidence  into  account.     His  hypothesis  merely  complicates 
the  problem  and  confuses  the  issues  by  introducing  the  entirely 
gratuitous  assumption  that  the  production  of  characters  depends, 
not  on  a  single  unit  or  hereditary  tendency  in  the  germ-plasm,  but 
on  two,  a  factor  and  a  determiner.     It  must  be  understood  that 
there  is  no  real   evidence  in  favour  of  this  hypothesis.     It  was 
invented  only  because  without  some  such  supposition  the  reproduc- 
tion   of  ancestral   traits  rendered  the   hypothesis  of  segregation 
untenable.      It  is  unnecessary,  therefore,  to  consider  what  have 
been  euphoniously  termed  the   *  later   refinements '  of  the  Men- 
delian  hypothesis,  such  as  negative  '  elements '  in  which  apparently 
*  absence '  constitutes  the  alternative  allelomorph.     As  I  say  the 
reproduction    of  ancestral  traits   by   pure-bred   races   constitutes 
decisive  proof  that  the  Mendelian  phenomena  are  due  to  alternate 
patency  and  latency,  not  to  segregation. 

282.  De  Vries  offers  yet   another   explanation   of  Mendelian 
phenomena.2     According  to  him  a  new  species  differs  from  the 
parent  stock  by  the  addition  of  a  fresh  progressive  character  (a 
mutation)  to  the  sum-total  of  ancestral  characters.     A  new  variety, 
on  the  other  hand,  differs  from  the  parent  stock  in  that  it  has 
latent  or  patent  a  character  which  is  in  the  opposite  condition  in 
the  parent  stock.     When,  therefore,  species  cross  they  tend  to  be 
more  or  less  sterile,  for  the  character  is  unpaired ;  or  if  the  union 
is  fertile  there   tends   to   be   more   or   less   of  blending.     When 
varieties  cross  with  the  parent  type  the  patent  character  is  dominant 
over  the  latent  character,  and  there  is  Mendelian  inheritance,  with 
segregation  of  patent  and  latent  units  in  succeeding  generations. 
But,  if  this  theory  be  correct,  the  albino  rabbit  must  have  been 
latent  in  the  yellow-grey,  the  yellow-grey  in  the  albino,  and  the 
black,  wild-grey,  and  Dutch  colorations  in  both.     The  ancestors 
of  both  races,  therefore,  must  have  been  all  these  colours  in  turn 

1  Animals  and  Plants,  vol.  ii.  p.  29. 

1  Species  and  Varieties.    Their  Origin  by  Mutation.     Lectures  IX  and  X. 


SUMMARY  167 

at  one  time  or  another,  which  is  very  improbable.  Again,  since 
the  inheritance  of  polydactylism  in  man  and  the  lower  animals  is 
alternative,  Professor  de  Vries'  theory  involves  the  corollary  that 
mammals  have  descended  from  ancestors  which  possessed  six 
digits,  one  of  which  has  become  latent,  which  also,  to  say  the  least, 
is  very  improbable. 

283.  Taking  all  the  facts  into  consideration,  I  think  there  can 
be  no  doubt  that  reproduction  of  at  least  many  mutations  is  alter- 
native from  the  first.     The  only  matter  open  to  doubt  (and  even 
that,  as  we  see,  is  not  open)  is  whether  the  alternation  involves 
alternative  inheritance  (unit   segregation  and  gametic  purity)  or 
merely  alternative  development  (alternative  patency  and  latency). 
Great  stress  is  often  laid  on  the  frequency  with  which  alternative 
characters  are  reproduced  in  the  second  mongrel  generation  in  what 
are  known  as  the  Mendelian  proportions.     Thus,   if  round    and 
wrinkled  peas  are  crossed,  the  average  proportions  in  the  second 
mongrel  generation  are  three  round  peas  to  one  wrinkled  ;  if  rose 
comb  is  crossed  with  pea  comb,  the  proportions  are  nine  walnut 
combs,  three  rose,  three  pea,  and  one  single.     These  proportions 
are  certainly  very  interesting  and   remarkable.      Beyond    doubt 
they  suggest  segregation  rather  than  patency  and  latency.     But 
suggestion  is  not  the  same  thing  as  demonstration.     The  latter 
must  depend  on  surer  evidence,  such  as  that  furnished  by  pure- 
bred varieties.     Here,  as  I  say,  we  have  positive  testimony  that  the 
Mendelian  phenomena  do  not  indicate  segregation. 

284.  To   sum    up :  we  have    a    choice    between   two   possible 
explanations  of  Mendelian  phenomena.     On   the  one  hand  is  the 
orthodox  Mendelian  doctrine  of  dominance  (patency  and  latency)  in 
the  first  hybrid  generation,  and  segregation  and  gametic  purity  in 
the  pure  dominants  and  recessives  of  succeeding  generations  ;  on 
the  other  hand  is  the  theory  of  temporary  patency  and  latency  in 
the  first  generation  and  more  perfect  and  permanent  patency  and 
latency  in  the  pure  dominants  and  recessives  of  succeeding  genera- 
tions.    I  am  hot  aware  of  any  fact  in  the  whole  range  of  Mendelian 
literature  that  contradicts    the   second    theory.     But   the   first   is 
contradicted  by  the  facts  (i)  that  pure  dominants  and  recessives 
may  occur  in  the  first  hybrid  generation  •  (2)  that  apparently  pure 
dominant  races  may  produce  recessives,  and  recessive  races  domi- 
nants ;  (3)  that  dominants  and  recessives  may  occur  in  altogether 
disproportionate  numbers  in  any  generation  succeeding  the  first ; 
(4)    that    extracted7  dominants     and     recessives      nearly    always 
bear  traces   of  their  hybrid    origin  (i.e.  display  some    degree   of 


1 68  MENDEL'S  LAWS 

patency  of  the  latent  allelomorph) ;  and  (5)  that  in  a  very 
great  number  of  cases  (i.e.  in  pure-bred  varieties)  it  has  been 
actually  proved  that  pure  dominants  and  recessives  carry  the 
alternative  unit  in  a  latent  condition.  Moreover,  the  analogy  of 
the  sexual  characters  points  clearly  to  latency  rather  than  to 
segregation. 


CHAPTER  VIII 
THE  MUTATION  THEORY 

The  nature  of  mutations — The  impossibility  of  distinguishing  between 
fluctuations  and  mutations  by  means  of  experiment — The  alleged  immutability 
of  mutations — Our  power  of  studying  smaller  variations — Human  inter-varietal 
crossings — Latent  characters  are  common  when  domestic  varieties  cross  ;  they  are 
rare  when  natural  varieties  cross — The  effects  of  Natural  and  Artificial  selection 
are  not  identical — Objections  to  the  mutation  theory — The  distinction  between 
inheritance  and  reproduction — The  modes  in  which  mutations  are  inherited  and 
reproduced. 

285.  "\~lt  THETHER  due  to  unit  segregation  and  gametic 
^y\/  purity,  or  to  patency  and  latency  of  the  components 
of  compound  allelomorphs,  there  can  be  no  doubt 
of  the  actual  occurrence  of  the  Mendelian  phenomena.  We  must 
endeavour,  therefore,  to  estimate  the  part  played  by  them  in  nature. 
The  more  extreme  section  of  the  experimental  school  insists  that 
all  those  differences  (even  minute  differences)  between  parents  and 
children  which  we  have  defined  as  variations  (innate  or  germinal 
differences,  differences  in  hereditary  tendencies)  are  mutations, 
that  the  inheritance  of  all  mutations  is  Mendelian,  and  that  muta- 
tions are  permanent  changes  which  "  selection  alone  can  eliminate," 
whereas  '  continuous,'  *  normal/  or  '  fluctuating  '  variations  are  mere 
modifications  due  to  changes  in  the  action  of  the  environment.  Con- 
sequently, according  to  them,  all  evolution,  at  any  rate  all  permanent 
and  considerable  evolution,  is  founded  solely  on  mutations.  It 
follows  if  this  hypothesis  be  true,  that  the  stability  of  racial 
characters  is  due,  not  to  their  long-continued  selection,  but  to  the 
circumstance  that  they  have  arisen  through  the  accumulation  of 
mutations,  all  of  which  were  stable  from  the  first.1 

1  "  Doubtless  some  of  the  so-called  fluctuations  are  in  reality  small  mutations, 
whilst  others  are  due  to  environmental  influence.  The  difficulty  of  distinguishing 
between  the  two  is  very  great.  The  simultaneous  existence  of  small  mutations 
and  large  fluctuations  leads  to  the  disguising  of  the  former  by  the  latter.  Only 
careful  and  laborious  analysis  will  avail  us  here,  and  such  analysis  is  precisely 
what  is  at  present  lacking.  The  position  is  roughly  as  follows.  Of  the  inheritance 
of  mutations  there  is  no  doubt.  Of  the  transmission  of  fluctuations  there  is  no 
very  strong  evidence.  It  is  therefore  reasonable  to  regard  the  mutation  as  the 
main,  if  not  the  only  basis  of  evolution.  And  the  great  service  which  Mendel  has 

169 


THE  MUTATION  THEORY 

286.  The  word  mutation  is  one  of  the  loose,  ill-defined  terms 
so  common  in  biology  and  the  bane  of  it.  Thus,  to  Mr  Punnett 
it  implies  a  variation,  large  or  small,  which  is  stable  because  the 
inheritance  of  it  is  Mendelian.  To  Professor  de  Vries  it  implies 
a  '  sport/  1  a  change  "  of  wide  amplitude,"  2  the  inheritance  of  which 

rendered  to  this  branch  of  philosophy  is  the  demonstration  of  the  fact  that  the 
mutation  when  once  it  has  arisen  is  not  likely  to  be  swamped  by  interbreeding 
with  the  normal  form,  provided  that  it  is  not  injurious  to  the  species.  We  now 
recognize  discontinuity  in  inheritance  as  well  as  in  variation.  The  new  character 
which  arises  as  a  mutation  has  its  representative  in  the  gamete.  Once  it  has 
arisen  selection  alone  can  eliminate  it.  Mendel's  discovery  then  has  led  us  to 
materially  alter  our  ideas  of  the  evolutionary  process.  The  small  fluctuating 
variations  are  not  the  materials  on  which  selection  works.  Such  fluctuations  are 
often  due  to  conditions  of  the  environment,  to  nutrition,  correlation  of  organs, 
and  the  like.  There  is  no  indisputable  evidence  that  they  can  be  worked  up  and 
fixed  as  a  specific  character  "  (Mr  R.  C.  Punnett,  Mendelism,  ed.  ii.,  pp.  72-3). 
"  Modification  of  characters  by  selection,  when  sharply  alternative  conditions  (i.e. 
mutations)  are  not  present  in  the  stock,  is  an  exceedingly  difficult  and  slow  process, 
and  its  results  of  questionable  permanency.  Even  in  so-called  '  improved  ' 
breeds,  which  are  supposed  to  have  been  produced  by  this  process,  it  is  more 
probable  that  the  result  obtained  represents  the  summation  of  a  series  of  mutations 
rather  than  that  of  ordinary  fluctuating  variations.  For  mutations  are  per- 
manent ;  variations  are  transitory.  A  moment's  reflection  will  indicate  the 
probable  reason.  Variations  which  are  distributed  symmetrically  about  a  modal 
condition,  so  as  to  produce  when  graphically  expressed  a  frequency  of  error  curve, 
represent  the  result  of  a  number  of  causes  acting  independently  of  each  other. 
These  causes  are  principally  external,  consisting  in  varying  conditions  of  food 
supply,  temperature,  density,  moisture,  light,  etc.  These  conditions  alter  from 
generation  to  generation,  and  so  do  effects  dependent  upon  them.  Mutations, 
on  the  other  hand,  have  an  internal  origin,  in  the  hereditary  substance  itself. 
They  are  relatively  independent  of  the  environment,  being  affected  only  by  such 
causes  as  affect  the  nature  of  the  hereditary  substance  itself,  one  of  which  ap- 
parently is  cross  breeding  "  (Professor  M.  E.  Castle,  "  The  Mutation  Theory  of 
Organic  Evolution,  from  the  Standpoint  of  Animal  Breeding."  Science,  April  7, 
1905).  "  Lop-eared  rabbits  have  ears  two  or  three  times  as  long  and  as  wide 
as  those  of  ordinary  rabbits.  A  cross  between  lop-eared  rabbits  and  ordinary 
ones  produces  offspring  with  ears  of  intermediate  size,  which  sometimes  stand  erect 
and  sometimes  lop.  The  ear  characters  which  were  so  distinct  in  the  parents  have 
in  this  case  lost  their  identity  in  the  offspring,  and  apparently  cannot  be  recovered 
again  in  the  original  condition,  for  the  offspring  transmit  to  their  young  the  blended 
character  rather  than  the  extreme  conditions  found  in  their  respective  parents  " 
(Castle,  "  Recent  Discoveries  in  Heredity"  Popular  Science  Monthly,  pp.  194-5). 
Professor  Castle  refutes  himself  in  a  very  interesting  way.  Probably  no  one  will 
deny  that  the  lop-eared  condition  has  an  "  internal  origin  in  the  hereditary 
substance  itself."  Certainly  it  is  quite  permanent  in  the  race  and  has  no  appear- 
ance of  depending  on  "  varying  conditions  of  food-supply,  temperature,  density, 
moisture,  light,"  etc.  But  it  blends  with  the  ordinary  ear.  Therefore  it  cannot 
have  resulted  from  a  mutation  the  inheritance  of  which  was  Mendelian  ;  for 
if  it  blends  now,  it  must  have  blended  formerly.  Therefore  it  must  have  resulted 
from  the  selection  of  fluctuations  the  inheritance  of  which  was  blended. 

1  Species  and  Varieties,  p.  191. 

*Op.  cit.,  p.  715. 


THE  INADEQUACY  OF  EXPERIMENT  171 

is  not  alternative,  which  tends  to  be  stable  because  it  involves 
the  acquisition  of  a  new  unit1  by  the  germ-plasm,  but  which  is 
necessarily  stable  only  when  the  individual  possessing  it  mates 
with  a  similar  individual.2 

287.  A   little   thought   renders   it   evident   that   none   of  the 
problems  raised  by  the  Mendelian  and  Mutation  hypotheses  can 
be  solved  on  the  data  furnished  by  experiment  alone.     Experi- 
mental evidence  lacks  minuteness  and  precision.     It  is,  besides,  far 
too   fragmentary.      Thus   experiments  which   cover   only  a   few 
generations    are   absurdly    inadequate   to   decide    the    questions 
whether  or  not  mutations  are  permanent  and  whether  evolution 
can  or  cannot  be  founded  on  the  continued  selection  of  fluctuations. 
If,  however,  we  turn  to  the  more  ample  and  conclusive  evidence 
afforded  by  the  life-history  of  species,  we  see  at  once  that  of  the 
two  deductions  that  evolution  is  founded  on  mutations  and  that 
mutations   are   permanent,  one   must  be   wrong,  for,  with   mere 
cessation  of  selection,  every  character  (e.g.  eyes  and  limbs)  tends 
to  retrogress  till  it  disappears.     The  statement  that  mutations  are 
immutable  is  a  very  good  example  of  the  mistaken  judgments 
which  tend  to  follow  too  exclusive  a  reliance  on  the  meagre  results 
obtainable  by  a  single  method  of  inquiry.     The  observer  is  con- 
stantly under  the  temptation  to  draw  inferences  larger  than  are 
warranted  by  the  scanty  data  at  his  command.     It  is  interesting 
to  note  that,  since  mutations  may  be  small,  what  Darwin  and  his 
followers  call  variations  (changes  "  which  have  an  internal  origin 
in  the  hereditary  substance  itself"),  some  members  of  the  experi- 
mental school  term  mutations ;  and  what  the  former  call  acquire- 
ments (due  to  "varying   conditions  of  food-supply,  temperature, 
density,  moisture,  light,"  etc.),  the  latter  term  variations.     Except 
that  we  are  told  that  mutations  do  not  blend  or  retrogress,  nothing 
more  is  done  than  to  change  the  names  and  conduct  the  argument 
on  that  basis. 

288.  Again,  the  question  as  to  whether  the  larger  variations 
(i.e.  the  mutations  of  de  Vries)  are  more  permanent  than  smaller 
variations  (i.e.  fluctuations  and  the  small  mutations  of  Punnett), 
and   whether   the   inheritance   of  small    mutations   tends    to   be 
alternative,  cannot  be  decided  by  the  mere  experimental  observer. 
He  has  no  special  knowledge  of  the  lesser  variations,  for  the  study 

1  "  We  may  assume  that  these  units  are  represented  in  the  hereditary  substance 
of  the  cell-nucleus  by  definite  bodies  of  too  small  a  size  to  be  seen,  but  constituting 
together  the  chromosomes."     Op.  cit.,  p.  306. 

2  Op.  cit.,  Lecture  IX. 


172  THE  MUTATION  THEORY 

of  which  his  method  is  unsuited.  The  whole  literature  of  experi- 
mental inquiry  may  be  ransacked  and  not  a  single  observation 
on  the  smaller  variations  will  be  found.  "  For  almost  always 
the  points  which  tell  are  too  fine  to  be  dealt  with  in  our  analysis." 1 
Probably  domesticated  poultry,  owing  to  the  number  and  diversity 
of  the  varieties  and  the  ease  with  which  they  may  be  bred,  and 
the  offspring  compared  with  the  parents  and  with  one  another, 
have  been  the  subject  of  more  exhaustive  experimental  study  than 
any  other  type.  The  method  of  study  in  this  case,  as  in  all  others, 
has  always  been  to  cross  the  more  dissimilar  varieties — a  rumpless 
fowl  with  one  possessing  a  rump,  a  long-tailed  fowl  with  a  short- 
tailed  one,  a  white  individual  with  a  black,  and  so  on.  The 
following  is  a  fairly  complete  list  of  the  characters  studied  : — 

Comb  form.  Uropygium.  Ear-lobe  colour. 

Nostril  form.  Tail  length.  General  plumage 

colour. 

Cerebral  hernia.         Vulture  hock.  Colour  of  hackles. 

Crest.  Booting.  Wing  bars. 

Muff.  Extra  toe.  Shafting. 

Beard.  Colour  of  mandible  and  Body  lacing. 

foot. 

Frizzling.  Iris  colour.  Pencilling.2 

Obviously  we  do  not  study  the  smaller  variations,  the  *  fluctuations,' 
when  we  cross  any  one  of  these  characters  with  its  opposite. 
They  are  great  differences  which  have  arisen  as  sports  or  been 
established  by  generations  of  careful  selection,  not  those  small 
variations  which  commonly  distinguish  mating  individuals  when 
the  breeding  is  **/tti-varietaL 

289.  Our  power  of  observing  small  differences  is  proportionate 
to  our  familiarity  with  the  object  of  study.  Thus  the  shepherd  is 
able  to  distinguish  between  the  individuals  of  his  flock  and  even 
to  note  a  good  deal  when  he  sees  a  strange  flock ;  but  the  ordinary 
observer  can  hardly  distinguish  one  variety  of  sheep  from  another 
unless  they  display  some  glaring  differences  of  size,  shape,  or  colour. 
To  the  Englishman  landing  in  China  the  natives  seem  as  much 
alike  as  peas — as  in  fact  they  are.  He  becomes  trained  in  time  to 
distinguish  Chinamen,  but  not  peas.  But  from  earliest  infancy  we 
are  forced  to  observe  very  closely  the  human  beings  among  whom 
we  are  reared.  Indeed  it  is  a  main  business  of  our  lives  to  do  so. 

1  Bateson,  Mendel's  Principles  of  Heredity,  p.  vii. 

8  Quoted  from  Inheritance  in  Poultry,  by  Mr  C.  B.  Davenport,  p.  81. 


THE  INADEQUACY  OF  EXPERIMENT  173 

So  acute  does  our  observation  become  that  when  we  have  once  seen 
and  noted  a  face  we  are  usually  able  to  distinguish  it  again  even  after 
the  passage  of  months  or  years.  Here  our  power  of  discrimination 
far  surpasses  our  power  of  expression  in  words.  Nevertheless,  so 
confusing  is  the  effect  of  modifications  and  spontaneous  variations 
that,  even  in  the  members  of  our  own  families,  we  are  unable  to 
note  clearly  the  effect  produced  by  the  crossing  of  parental 
differences,  though  these  are  often  considerable.  No  experimental 
observer,  no  matter  to  what  an  extent  a  recluse  and  a  student,  is  as 
familiar  with  any  type  of  animal  or  plant  as  he  is  with  human 
beings,  for,  at  least,  he  is  always  more  intimate  with  himself,  a 
human  being,  than  with  anything  else.  Much  less,  therefore,  is 
his  power  of  observing  the  inheritance  of  small  differences  in  other 
types.  When,  therefore,  relying  on  experimental  evidence,  he 
states  that  the  inheritance  of  the  smaller  mutations,  like  that  of 
'  sports,'  is  alternative,  or  when  he  declares  that  all  true  variations 
are  mutations,  and  therefore  extremely  stable,  he  is  guessing.  He 
has,  as  I  say,  no  data  on  which  to  found  a  judgment.  Unless  we, 
also,  are  content  merely  to  guess,  we  must  test  his  hypotheses  by 
the  ordinary  scientific  procedure  of  making  a  rigorous  deductive 
inference  of  consequences  followed  by  an  appeal  to  nature,  to 
ascertain  whether  these  consequences  accord  with  reality.  The 
reader  must  bear  in  mind  that  the  experimental  evidence  is  not 
neglected  when  more  is  added  to  it,  and  the  thinking  not  the 
less  likely  to  be  correct  because  we  use  our  best  endeavours  to 
ensure  its  accuracy.  I  do  not  think  it  will  be  possible  to  contest  a 
single  fact  of  this  added  evidence  which  I  shall  adduce  ;  and,  if  it 
is  incontestible,  then,  as  far  as  I  am  able  to  judge,  the  conclusions 
we  shall  reach  follow  as  necessary  consequences. 

290.  When  we  cross  two  varieties  of  fowls  or  any  other 
domestic  animals  or  plants,  then,  as  regards  the  differences  we  are 
able  to  note — the  larger  differences — the  development  is  often 
alternative.  There  is  usually  some  blending  observable  both  in 
the  first  and  in  the  succeeding  hybrid  generations ;  but  it  is  not 
the  conspicuous  feature.  The  conspicuous  feature  is  alternative 
reproduction  ;  the  resemblance  to  one  parent  type  is  much  closer 
than  to  the  other;  there  is  seldom  such  blending  that  both  the 
opposing  parental  characters  are  equally,  or  nearly  equally  repre- 
sented. Now  races  of  men  differ  among  themselves  in  size, 
shape,  colour,  and  so  on,  almost  as  much  as  do  varieties  of  poultry. 
If  human  varieties  cross,  and  almost  every  human  variety  has 
crossed  repeatedly  with  almost  every  other,  the  inheritance  of 


1/4  THE  MUTATION  THEORY 

parental  differences  is  never  alternative.  As  regards  a  few 
features — I  can  think  only  of  eye-colour — the  characters  of  a  dark 
race  may  dominate  over  those  of  a  light-coloured  one;  but  the 
dominance  is  permanent ;  it  is  transmitted  to  all  the  members  of 
all  succeeding  generations  that  breed  together.  Therefore  the 
reproduction  is  not  Mendelian.  But  as  regards  the  great  majority 
of  characters  the  blending  is  perfect  and  often  nearly  equal,  and 
as  such  is  transmitted  to  the  latest  descendants.  A  race  of  per- 
manent and  patent  mongrels  is  formed.  If  three  or  four  races  are 
crossed  together,  as  has  happened  in  South  America,  each 
contributes  its  quota  in  perpetuity  to  the  blend.  It  is  a  common 
belief  amongst  experimental  workers  that  "  a  fusion  of  characters 
is  rather  a  rare  phenomenon.  Human  skin-colour  is  the  one 
striking  case."  But  really  that  is  very  wrong.  Fusion  is  very 
much  the  general  rule,  not  the  exception.1  The  fact  that  the 
gametes  of  the  cross  blend  "  is  as  strong  an  indication  as  can  be 
desired  of  the  '  continuity '  between  them."  2  When  the  negro,  for 
example,  crosses  with  a  white  race,  the  offspring,  the  mulatto,  is 
conspicuously  a  blend  in  all  except  eye-colour.  His  hair,  it  is  true, 
more  closely  resembles  in  texture  the  African  than  the  Caucasian 

1  Strange  as  it  may  appear  to  people  who  have  travelled  in  Asia,  Africa, 
America,  Australasia,  or  Polynesia,  experimental  workers,  or  some  of  them, 
express  doubts  as  to  whether  human  races  really  blend.  "  It  would  be  extremely 
interesting  to  students  of  genetics  to  learn  upon  what  evidence  Dr  Archdall  Reid 
bases  his  positive  statement  that  there  is  no  segregation  in  the  case  of  the  Mulatto  " 
(Mr  R.  H.  Lock,  Nature,  Oct.  i/th  1907;  see  also  Bateson,  Mendel's  Principles  of 
Heredity,  pp.  208-9).  "  The  evidence  on  which  I  base  my  assertion  that  there  is 
no  segregation  in  the  mulatto  is  that  of  my  own  eyes.  Mulattos  vary  amongst 
themselves,  but  the  blend  is  usually  very  obvious  and  is  reproduced  in  subsequent 
generations  when  the  breeding  is  inter  se.  With  every  infusion  of  European  blood 
the  negro  type — skin  colour,  hair  texture,  shape  of  features,  and  [the  like — grows 
fainter  until  at  length  the  '  touch  of  the  tar  brush '  is  hardly,  if  at  all,  perceptible  ; 
and  this  blending,  as  far  as  I  am  aware,  occurs  not  only  in  all  crossed  human 
varieties,  but  in  other  natural  varieties  as  well.  There  may  be  exceptions,  in 
fact  I  believe  there  are ;  but  blending  appears  to  be  the  rule  in  the  vast  majority 
of  instances  "  (G.  Archdall  Reid,  Nature,  Oct.  jist  1907).  "  If  Dr  Archdall  Reid 
will  produce  authenticated  pedigrees  showing  the  repeated  crossing  of  the  mulatto 
with  pure  white  blood  and  pure  black  blood  respectively,  together  with  a  detailed 
account  of  all  the  offspring  produced,  he  will  make  a  very  substantial  contribution 
to  our  knowledge  of  heredity  in  the  human  race,  and  one  which  will  be  examined 
with  very  great  interest  by  Mendelians  "  (Mr  R.  H.  Lock,  Nature,  Nov.  i4th). 
"  Since  Mr  Lock  is  probably  the  only  human  being  who  doubts  the  blending  of  the 
black  and  white  races  in  Mulattos  and  their  descendants,  it  would  be  well  if  he, 
rather  than  I,  undertook  the  collection  of  pedigrees.  He  would  feel  himself  on 
the  track  of  a  great  discovery  which  would  enlighten  even  Mulattos,  whereas  I 
should  feel  I  was  wasting  time  "  (G.  Archdall  Reid,  Nature,  Nov.  2ist). 

*  See  footnote,  §  277. 


WHERE  DORMANT  TRAITS  ARE  ABSENT          175 

type,  but  proof  of  blending  is  furnished  by  the  fact  that  continued 
infusion  of  white  blood  in  succeeding  generations  results  in  a 
gradual  change  of  type  till  at  last  the  hair  loses  all  traces  of 
woolliness.  In  these  later  generations  also  the  colour  of  the 
eye  may  suddenly  be  changed  to  a  lighter  hue.  This  last  fact 
affords  another  crucial  instance  which  demonstrates  that  Mendelian 
inheritance  implies,  not  segregation,  but  latency.  The  inheritance 
of  eye-colour  is  alternative  in  ordinary  intra-varietal  breeding. 
But  when  a  white  race  is  crossed  with  a  black  the  eye-colour  of 
the  former  becomes  permanently  latent,  or,  at  least,  as  long  as 
the  mongrels  breed  together.  But  the  latency  is  weakened  by 
successive  infusions  of  white  blood,  till  at  length  the  descendants 
may  have  blue  or  hazel  eyes.  If  there  were  segregation  of  units 
accompanied  by  the  destruction  or  the  non-reproduction  of  those 
for  light  colour,  the  latter  could  never  reappear,  no  matter  how 
often  the  infusion  of  white  blood  were  repeated. 

291.  In  addition  to  manifesting  nearly  complete  general  blend- 
ing, human  races  when   crossed   differ  from    crossed   varieties  of 
domestic  plants  and  animals  in  another,  an  equally  remarkable, 
and  a  very  important  way.     Never  in  human  crossings  is  a  latent 
ancestral  character  brought  to  light,  whereas  the  reappearance  of  such 
characters,  dormant  perhaps  for  many  generations,  is  one  of  the 
most   conspicuous   results  of  the  crossing  of  domestic  varieties. 
Now  what  is  the  significance  of  these  very  remarkable  differences 
of  inheritance  ?     How  is  it  that  in  the  one  case  blended  inheritance 
is  the  rule,  whilst  in  the  other  alternative  reproduction  combined 
with    a   frequent   development    of    hitherto   latent   characters   is 
general  ?     If  we  are  able  to  unravel  this  mystery,  I  think  we  shall  be 
able  to  solve  those  problems  of  heredity  which,  of  recent  years,  have 
especially  occupied  the  attention  of  experimental  workers,  and  indeed 
of  most  biologists. 

292.  The  majority  of  experimental   observers  claim  that  the 
inheritance  of  mutations  is  alternative.     If  we  substitute  'develop- 
ment '  for  *  inheritance,'  the  evidence  that   they  are  right  seems 
clear,  at  least  as  regards  many  mutations.     In  man  occur  polydacty- 
lism,  hypophylangia,  alkaptonuria  (a   dark-coloured  condition  of 
the   urine),  haemophilia,  colour-blindness,  deaf-mutism,  and  other 
large    variations,1   all    of    which   may   be   classed   as   mutations, 
and  the  development  of  which  is  alternative.     Again,  the  majority 
of  experimental  observers   declare   that  a   mutation  is   properly 
defined   as   a    large    discontinuous   variation,   one   which   is   not 

1  See  §§  769-71. 


i;6  THE  MUTATION  THEORY 

connected  by  intermediate  links  with  smaller  variations.  Doubt- 
less in  this  also  they  are  right.  The  mutations  which  have  been 
discovered  in  man  all  display  this  peculiarity.  Yet  again  they 
claim  that  domestic  varieties  of  plants  and  animals  have  arisen,  not 
through  the  fixation  of  fluctuating  variations  by  continued  selection, 
but  through  the  artificial  selection  of  mutations.  Here,  also,  there 
is  good  reason  to  believe  that  they  are  right,  at  least  in  large 
measure.  Breeders  of  plants  and  animals  are  no  more  able  than 
experimental  workers  to  distinguish  the  smaller  differences  between 
mating  individuals.  Moreover,  they  are  in  haste  to  get  good 
results.  Of  necessity  they  have  selected  large  mutations  rather 
than  small  fluctuations.1  This,  however,  has  not  always  been  the 
case.  For  example,  when  evolving  speed  in  the  American 
trotting  horse,  a  favourable  mutation,  involving  as  it  would  a 
co-adaptive  change  in  a  thousand  structures — that  is  a  thousand 
co-ordinated  mutations — would  be  an  exceedingly  rare,  indeed,  an 
almost  impossible  occurrence.  Therefore  the  breeder  must  depend 
on  fluctuations,  which  in  this  case,  though  imperceptible  to  the 
eye,  can  be  measured  by  the  test  of  speed.  It  is  admitted  that  the 
inheritance  of  fluctuations  is  blended,  and  that,  as  regards  them, 
offspring  display  a  strong  tendency  to  return  to  the  ancestral 
type.  For  this  reason,  according  to  Mendelians,  do  trotting  horses 
tend  to  retrogress  unless  carefully  selected,  and  when  crossed  with 
inferior  types  to  transmit  blended  characters  to  descendants. 

293.  Experiments  in  crossing  have  been  limited  in  great 
measure  to  domestic  plants  and  animals.  Wild  types  are  less 
accessible,  more  difficult  to  manipulate,  and  often  more  or  less 
sterile  when  crossed.  When,  however,  the  cross  is  fertile,  the 
hybrid,  like  man,  usually  blends  the  parental  characters  and 
transmits  the  blend  to  its  descendants.  In  hardly  a  single  instance 
has  the  crossing  of  natural  varieties  revealed  a  latent  ancestral 
character?  Darwin  noted  long  ago  that  "  Gartner  further  states 
that  reversions  rarely  occur  with  hybrid  plants  raised  from  species 
which  have  not  long  been  cultivated,  whilst,  with  those  which  have 

1  "  He  [Man]  often  begins  his  selection  by  some  half -monstrous  form,  or  at 
least  by  some  modification  prominent  enough  to  catch  the  eye  or  to  be  plainly 
useful  to  him."  Origin  of  Species,  6th  ed.,  p.  60. 

*  I  know  of  only  one  to  which  my  attention  was  called  by  Sir  William  Thiselton- 
Dyer.  When  Kalanchce  flammea  was  crossed  at  Kew  with  K.  Benin,  the  hybrid 
displayed  characters  which  can  hardly  have  been  other  than  ancestral  traits 
which  have  remained  latent  in  one  or  other  species  (see  Morphological  Notes,  by 
William  Thiselton-Dyer,  K.C.M.G.,  F.R.S.,  Annals  of  Botany,  vol.  xvii.  No.  Ixvi., 
March  1903,  pp.  435-41- 


NATURAL  AND  ARTIFICIAL  VARIETIES  177 

been  long  cultivated,  they  are  of  frequent  occurrence.  This  con- 
clusion explains  a  curious  discrepancy :  Max  Wichura,  who  worked 
exclusively  on  willows  which  had  not  been  subjected  to  culture, 
never  saw  an  instance  of  reversion ;  and  he  goes  so  far  as  to 
suspect  the  careful  Gartner  had  not  sufficiently  protected  his 
hybrids  from  the  pollen  of  the  parent  species.  Naudin,  on  the  other 
hand,  who  chiefly  experimented  on  cucurbitaceous  and  other  culti- 
vated plants,  insists  more  strenuously  than  any  other  author  on  the 
tendency  to  reversion  in  all  hybrids.  The  conclusion  that  the 
condition  of  the  parent-species,  as  affected  by  culture,  is  one  of  the 
proximate  causes  leading  to  reversion,  agrees  well  with  the  converse 
case  of  domesticated  animals  and  cultivated  plants  being  liable  to 
reversion  when  they  become  feral ;  for  in  both  cases  the  organiza- 
tion or  constitution  must  be  disturbed,  though  in  a  very  different 
way."  * 

294.  We  are   driven   then  to  the  conclusion  that  Natural  and 
Artificial  selection  are  essentially  unlike.     Nature  and  man  do  not 
select   the   same   class    of   characters.       Man,   perforce,    chooses 
mutations.    Nature,  with  finer  powers  of  discrimination  and  with 
unlimited  time  and  material  at  her  disposal,  chooses,  perhaps  with 
very  rare  exceptions,  fluctuating  variations.     In  no  other  way  is  it 
possible  to  account  for  the  striking  differences  revealed  when  natural 
and  artificial  varieties  are  crossed.     It  is  known  that  man  tends  to 
select  mutations,  and  that  the  reproduction  of  mutations  tends  to 
be  alternative.     It  is  clear  that  when  reproduction  is  alternative, 
characters  tend  to  become  latent,  and  when  latent  to  become  patent 
in  cross-breeding.     If,  then,  as  experimental  workers  suppose,  nature 
chooses  mutations,  how  does  it  happen  that  natural  varieties, when  crossed, 
not  only  blend  very  often,  but  hardly  ever  reveal  latent  characters  ? 2 

295.  The  fact  that  natural  varieties  often  blend  their  characters 

1  Animals  and  Plants,  vol.  ii.  pp.  24-5. 

2  Since  latent  characters  are  in  effect  found  only  in  domesticated  varieties,  it 
follows  that  Darwin,  who  drew  the  materials  on  which  his  conclusion  was  founded 
wholly  from  artificial  varieties,  formulated  too  wide  an  inference  when  he  declared 
that,  "  besides  the  visible  changes  which  it  [the  germ]  undergoes,  we  must  believe 
that  it  is  crowded  with  invisible  characters,  proper  to  both  sexes,  and  to  both  the 
right  and  left  side  of  the  body,  and  to  a  long  line  of  male  and  female  ancestors 
separated  by  hundreds  or  even  thousands  of  generations  from  the  present  time ;  and 
that  these  characters,  like  those  written  on  paper  with  invisible  ink,  lie  ready  to  be 
evolved  whenever  the  organization  is  disturbed  by  certain  known  or  unknown 
conditions  "  (Animals  and  Plants,  vol  ii.  pp.  35-6).     It  follows,  also,  that  Professor 
de  Vries  is  mistaken  in  defining  a  variety  as  a  type  which  has  patent  or  latent  a 
character  which  is  in  the  opposite  condition  in  the  parent  species.     A  type  which 
carries  a  latent  character  is  always  a  mongrel ;  for  it  is  only  when  varieties  possess- 
ing alternative  characters  cross,  that  latency  occurs.     Thus,  all  sexually  dimorphic 

12 


1 78  THE  MUTATION  THEORY 

when  crossed  is  decisive  proof  that  they  have  not  arisen  by  muta- 
tions, the  reproduction  of  which  is  alternative,  for  had  they  so 
arisen  the  cross-breds  would  also  display  alternative  reproduction. 
As  we  see,  artificial  varieties,  which,  admittedly,  have  arisen  by 
mutations,  display,  not  only  alternative  reproduction,  but  latent 
characters  in  abundance.  It  does  not  follow,  however,  that  all 
characters  which  alternate  in  cross-breeding  have  arisen  by 
mutation.  So  far  as  has  been  observed,  reproduction  is  alternative 
only  when  characters  are  sharply  contrasted ;  and  sharp  contrasts 
may  arise  as  well  by  the  piling  up  of  fluctuations  occurring  during 
many  generations  as  by  single  mutations.  It  would  seem,  however, 
that  alternative  reproduction  is  much  more  the  rule  when  the 
contrast  has  been  reached  by  mutation  than  when  it  has  resulted 
from  the  accentuation  of  fluctuations. 

296.  On  the  other  hand,  if  it  be  contended  that  mutations 
occurring  in  wild  nature  have  been  preserved,  not  because  their 
reproduction  was  alternative,  but  because  the  mutants  were  sterile 
with  the  parent  type  but  fertile  inter  se,  then  it  must  be  shown 
that  mutations,  not  only  useful  but  similar  in  kind,  occur  in  such 
numbers  that  physiological  isolation  l  without  extinction  is  possible. 
The  fact  that  human  races  are  fertile  when  crossed  is  proof  that 
physiological  isolation  can  have  played  no  part  in  their  differentia- 
tion. Unless,  then,  heredity  is  different  in  plants  and  lower 
animals  from  what  it  is  in  man,  we  must  believe  that  the  natural 
varieties  of  the  former  were  similarly  inter-fertile  at  their  origin, 
but  that,  in  many  of  the  cases  which  have  been  examined,  differen- 
tiation is  now  physiologically  greater  than  in  the  case  of  human 
races.  Doubtless  most  natural  varieties  are  more  ancient  than 
those  of  man  ;  for  few  species  can  have  so  quickly  invaded  diverse 
environments,  where  selection  differed,  as  the  human  being,  who 
is  omnivorous,  and  therefore  not  dependent  for  nutriment  on 

types  are  mongrels  (in  a  real  sense)  between  male  and  female.  Again,  the  human 
races  of  North- Western  Europe,  where  travel  and  interbreeding  have  been  so 
common,  and  which  in  the  past  has  been  so  often  invaded  by  alien  conquerors, 
are  mongrels  between  several  races,  as  is  shown  by  the  fact  that,  unlike  all  other 
animal  races,  they  have  variously  coloured  eyes.  Yet,  again,  the  albino  rabbit 
and  mouse  are  mongrels  between  the  white  and  the  ancestral  grey  types.  In 
this  connexion  it  matters  not,  of  course,  whether  a  variety  is  composed  of  many 
individuals,  or  of  only  a  single  individual  who  has  mutated  from  the  parent 
type.  De  Vries  states  that  latency  is  of  universal  occurrence  (Species  and 
Varieties,  p.  222),  but  he  gives  no  evidence.  He  mentions  instances  of  retrogres- 
sion in  plants,  and  assumes  (p.  631)  without  further  proof  that  it  implies,  not  total 
loss,  but  latency.  He  assumes,  in  effect,  that  while  the  germ-plasm  may  gain 
characters,  it  cannot  lose  them,  see  §  188. 
1  See  §  332. 


INUTILITY  OF  MUTATIONS  179 

special  plants  and  animals,  or  on  soil  or  climate,  and  who,  owing  to 
his  mental  powers,  is  otherwise  very  adaptable. 

297.  The  sole  warrant  for  the  belief  that  fluctuating  variations 
cannot  be  made  more  stable  by  continued  selection  is  furnished 
by  the  fact  that  recently  evolved  domestic  varieties,  such  as  the 
American  trotting-horse,  tend  to  retrogress  rapidly  when  no  longer 
selected.       We   have   already   discussed    this  question  in   part ; 1 
presently  we  shall  see  how  sex  is  instrumental  in  determining  the 
rapid  retrogression  of  characters  of  recent  origin.    The  sole  warrant 
for  the  hypothesis  that  the  organic  world  has  arisen  by  the  selection 
of  mutations  is  furnished  by  the  fact  that  some  mutations  have 
been  observed  in  wild  nature,  and  that  mutations  appear  excep- 
tionally stable.     Doubtless,  however,  they  are  common  enough. 
In  man,  the  only  natural  species  with  which  we  are  at  all  intimately 
acquainted,  they  are  very  common,  and  often  the  same  mutation 
is  repeated  in  many  individuals.     The  medical  profession  owes  its 
prosperity  largely  to  them  :  they  fill  our  hospitals ;  surgeons  are 
busy  every  day  rectifying  such  mutations  as  hare-lip  and    club- 
foot.     But  never  yet  has  a  mutation  been  recorded — neither  in  man, 
nor  in  lower  animals,  nor  in  plants — that  gave  its  possessors  an 
advantage    in  the   struggle  for   existence  so  overpowering   that 
it  enabled  them  to  supplant  the  ancestral   type.     And  hardly  a 
mutation  has  been  recorded  which  enabled  its  possessors  to  persist 
alongside  the  parent  variety,  at  any  rate  when  the  reproduction 
was  bi-parental.2 

298.  Mutationists  declare   that   the  general  failure   to   detect 

1  See  §  182. 

2  The  most  widely  discussed  mutations  are  those  of  (Enothera  lamarckiana,  an 
evening  primrose,  investigated  by  de  Vries.     Several  species  of  evening  primroses 
were  brought  to  Europe  from  America  during  the  seventeenth  and  eighteenth 
centuries.     It  is  not  known  when,  if  ever,  O.  lamarckiana  was  introduced.     It 
was  first  observed  by  Lamarck  at  the  beginning  of  the  last  century  in  a  garden  at 
Paris,  and  at  once  recognized  as  a  type  new  to  science.    The  fact  that  this  '  stately,' 
'  beautiful,'   and   noticeable  plant  was  previously  unknown   to  botanists,   the 
circumstances  under  which  it  was  discovered,  and  the  fact  that  it  is  not  known 
to  grow  wild  anywhere  in  America,  render  it  likely  that  it  originated  as  a  garden 
variety  in  Europe,  possibly  in  the  very  garden  in  which  Lamarck  found  it.     Most 
probably,  like  so  many  other  cultivated  varieties,  it  is  a  mongrel,  possessing  an 
unknown  number  of  latent  characters.     At  any  rate  it  is  a  descendant  of  a  wild 
American  plant,  which,  for  more  than  a  century,  had  been  cultivated  in  Europe, 
and  which,  presumably  owing  to  changes  in  selection  due  to  the  great  changes  in 
its  environment  and  possibly  to  crossing,  had  become  highly  variable.     The 
patch  of  plants  in  which  de  Vries  discovered  his  mutants  from  O.  lamarckiana 
had  escaped  from  cultivation  and  was  growing  wild  in  a  disused  potato  field. 
More  mutations  occurred  after  he  had  altered  the  environment  yet  again  by  re- 
moving specimens  to  his  garden,  where  he  cultivated  the  plants  on  a  large  scale. 


i8o  THE  MUTATION  THEORY 

favourable  discontinuous  variations  in  wild  nature  is  due  solely  to 
difficulties  of  observation.  But  there  are  no  such  difficulties  in 
observing  the  neglected  human  species  which  we  are  so  very  capable 
of  observing.  It  is  not  really  beneath  the  dignity  of  science  to  utilize 
familiar  facts.  Mankind  has  spread  over  the  whole  habitable 
globe ;  it  inhabits  very  diverse  environments ;  it  is  numbered  in 
millions,  and  has  hundreds,  if  not  thousands  of  stable  varieties. 
Some  races  such  as  the  Esquimaux  and  the  Tierra-del-Fuegians, 
are  apparently  as  '  pure '  as  natural  races  of  lower  animals ;  others 
are  simple  mongrels ;  yet  others  are  compound  mongrels. 
Some  mongrel  human  races  are  very  ancient ;  others  are  com- 
paratively new.1  Racial  changes  of  a  permanent  sort  there  have 

The  mutants,  which  were  of  at  least  seven  different  types,  were  comparatively 
few  in  number  in  the  field.  Most  of  the  types  were  weakly  and  perished.  In  the 
field  two  types  "  have  held  their  own  during  the  last  sixteen  years,  and  probably 
more,  without,  however,  being  able  to  increase  their  numbers  to  any  noticeable 
extent.  Others  perish  as  soon  as  they  make  their  appearance,  or  a  few  individuals 
are  allowed  to  bloom,  and  probably  leave  no  progeny.  But  perhaps  the  cir- 
cumstances may  change,  or  the  whole  strain  may  be  dispersed  and  spread  to  new 
localities  with  different  conditions.  Some  of  the  latter  may  be  found  favourable 
to  the  robust  gigas  or  rubrinervis,  which  requires  a  dryer  air,  with  rainfall  in  the 
spring-time  and  sunshine  during  summer  "  (Species  and  Varieties,  p.  574).  Muta- 
tions are  comparatively  few,  changes  of  climate  rare,  and  the  dispersal  of  most 
plants,  except  by  human  agency,  slow.  The  chance  of  these  mutations  surviving 
in  nature  seems,  therefore,  somewhat  remote.  It  is  significant  that  de  Vries 
"  made  experiments  with  some  hundred  species  that  grow  wild  in  Holland.  .  .  . 
No  real  mutability  could  be  discovered  "  (p.  520)  in  the  native  plants  growing 
in  their  ancestral  environment.  Or,  to  express  the  fact  in  other  and  probably 
more  correct  terms,  these  natural  varieties  revealed  no  latent  characters.  To 
account  for  the  fact  that  O.  lamarckiana  mutated  frequently  while  the  native 
Dutch  plants  mutated  not  at  all,  the  hypothesis  was  formulated  that  in  the  life- 
histories  of  species  periods  of  great  mutability  alternate  with  periods  of  stability. 
"  Of  course  this  mutable  state  must  have  had  a  beginning,  as  it  must  sometimes 
come  to  an  end.  It  is  to  be  considered  as  a  period  within  the  lifetime  of  the 
species,  and  probably  it  is  only  a  small  part  of  it  "  (p.  29).  Manifestly  this  de- 
duction, like  that  of  colour-factors,  is  a  pure  guess,  invented  to  bolster  up  another 
hypothesis  which  was  found  not  to  agree  with  reality.  We  may  predict 
with  entire  confidence  that  every  variety  which  has  evolved  under  artificial 
selection  and  has  been  frequently  crossed  is  an  '  eversporting  variety,'  whereas 
every  species  which  has  evolved  under  Natural  Selection  is  stable. 

1  "  In  the  case  of  a  problem  like  that  of  man,  complicated  as  it  is  by  the  fact 
that  he  has  '  crossed  more  often  than  any  other  animal,'  and  further  rendered 
intractable  by  the  circumstance  that  he  is  not  amenable  to  experiment,  a  great 
difficulty  arises  in  discovering  which  are  the  actual  allelomorphs  concerned  " 
(Mr  R.  H.  Lock,  Nature,  i/th  Oct.  1907).  "  How  can  the  fact  that  human  races 
have  crossed  more  often  than  any  other  animal  complicate  the  problem  ?  My 
statement  implied,  not  that  every  race  is  a  chaotic  mixture  of  types,  nor  even  that 
there  are  no  pure  types,  but  only  that  we  have  here  a  very  large  and  varied  mass 
of  material  on  which  to  found  our  judgments  "  (G.  Archdall  Reid,  Nature,  Oct. 
3ist  1907). 


HUMAN  RACIAL  DIFFERENTIATION  181 

been  in  plenty.  In  some  places,  as  in  parts  of  New  Guinea,  where 
war  is  nearly  perpetual  and  inter-marriages  between  tribes 
comparatively  rare,  the  inhabitants  of  almost  every  district,  like 
the  land  shells  of  Samoa1  display  stable  characters  which  clearly 
differentiate  them  from  their  neighbours.  Even  in  Great  Britain 
we  have  still  these  local  races,  as  in  the  Yorkshire  dales  and  High- 
land glens.  So  surely  as  a  human  race  separates  into  two  or  more 
sections  between  which  interbreeding  is  restricted,  just  so  surely 
does  differentiation  set  in.  The  section  that  remains  in  the 
ancestral  environment  continues  comparatively  stable ;  the  section 
that  migrates  undergoes  swifter  but  always  continuous  and  steady 
adaptive  change.  Evidently  there  has  been  no  lack  of  such  varia- 
tions as  contribute  to  stable  differentiation. 

299.  If,  then,  evolution  is  due  solely  to  mutations,  how  does  it 
happen  that  no  favourable  human  mutations  have  been  noted — 
neither  large  observable  mutations,  nor  those  which  render  mating 
physiologically  sterile  ?     The  latter  certainly  have  not  occurred,  for 
differentiated   human    races   are    perfectly    fertile   when   crossed. 
The  former  as   certainly  have  not  occurred  ;  for  written  human 
history  stretches  into  thousands  of  years,  and  men  are  fond  of 
recording  wonders,  and  none  of  this  kind  have  been  recorded. 
I    think  no   mutationist,   in    face   of  this  massive   evidence,   will 
venture  to  uphold  the  thesis  that  human  differentiation  has  resulted 
from    mutations.     And,    if  not   human   differentiation,   why    the 
differentiation  of  other  natural  species  and  varieties  ?     As  I  say,  we 
have  no  reason  to   suppose   that   heredity    in   the    animal   man 
differs  from  heredity  in  lower  animals  and  in  plants. 

300.  In  a  few — speaking  comparatively,  a  very  few — instances, 
mutations,   occurring   chiefly   in   self-fertilized   plants,  have  been 
known  to  persist  without  artificial  aid  for  several  generations.2     In 
every  such  case  the  mutation  has  been  comparatively  unimportant 
as  regards  the  function  of  the  part  that  has  undergone  change.     A 
leaf  or  a  flower  has  altered  its  shape  or  colour  or  texture,  a  flower- 
stem  has  grown  longer  or  shorter,  the   wing  of  a   butterfly  has 
grown  darker,  and  so  forth.     But  all  organs  are  not  on  the  surface 
of  the  body  ;  their  co-adaptations,  therefore,  are  not  always  so  few 
and  simple  as  those  of  leaves  and  flowers.     Consider  a  mutation 

1  See  §  332. 

*  The  only  mutation,  human  or  other,  if  mutation  it  can  be  called,  known  to 
have  been  persistent  under  natural  conditions  for  a  considerable  length  of  time, 
of  which  I  am  aware,  is  the  Hapsburg  lip,  an  ungainly  feature  of  the  reigning 
house  of  Austria.  I  imagine  it  would  have  disappeared  long  ago  if  the  faces  it 
marred  had  not  belonged  to  an  inbred  imperial  family* 


1 82  THE  MUTATION  THEORY 

occurring  within  that  immensely  complex  and  delicately  adjusted 
machine,  a  higher  animal.  To  be  useful  the  mutation  must 
not  only  be  an  improvement  in  itself,  but  it  must  be  correlated  to 
a  thousand  readjustments — a  thousand  co-adapted  mutations  in 
other  parts  of  the  machine.  Otherwise  it  will  be  positively  harm- 
ful.1 Indeed,  the  principal  difficulty  to  be  surmounted  by  the 
supporters  of  the  mutation  hypothesis  is  not  adaptation  to  the 
environment  but  co-adaptation  within  the  organism.  Suppose, 
however,  we  cede  the  point,  and  agree  that  the  miracle  may  happen 
and  a  thousand  co-adapted  mutations  may  occur  in  a  single  indi- 
vidual. Then,  either  the  reproduction  will  be  blended,  or  it  will  be 
alternative.  If  it  be  blended,  the  mutation  will  be  swamped  unless 
more  miracles  happen  and  many  other  individuals  mutate  in  the 
same  way  and  at  the  same  time  and  place.  If  it  be  alternative, 
the  co-adaptation  will  be  lost  in  succeeding  generations  through 
mixture  with  the  characters  of  individuals  who  have  not  mutated  ; 
for  Mendelian  observers  insist,  and  very  rightly,  that  the  alternative 
characters  are  reproduced  independently  of  one  another,  and 
that  all  the  characters  of  the  same  individual  are  not  necessarily 
patent  or  dormant  together. 

301.  It  must  be  noted,  morever,  that,  not  only  are  the  parts  of 
a  living  being  co-adapted,  but  that  different  species  of  animals 
and  plants  are  also  co-adapted  to  one  another.     Thus  the  plants 
which  herbivorous  animals  are  capable  of  using  as  food  possess 
great  powers  of  multiplying  themselves  and  of  reacting  to  the 
stimulus   of  injury,   of  regenerating   lost   parts.     Thus   also   the 
powers  of  pursuit  possessed  by  carnivora  are   closely  related  to 
the  powers  of  escape  possessed  by  their  prey.     If  evolution  were 
by  mutation,  then  a  mutation,  increasing  the  speed  of  one  species, 
could  only  be  met  by  a  mutation  occurring  at  the  same  time  and 
place,  increasing   the  speed   of  the  other.     For  example,  if  wild 
dogs  suddenly  mutated  in  this  way,  and  the  various  animals  they 
hunt  did  not,   the  inevitable  extinction  of  the  latter  would  soon 
be  followed  by  that  of  the  former. 

302.  It  is  possible  to  account  for  the  co-adaptation  of  parts 
and  species  to  one  another  on  the  theory  that  evolution  results 
from  the  continued  selection  of  constantly  occurring  small  fluc- 
tuations— from  the   constant   and   steady    change   of  species    in 
adaptation  to  changes  in  their  surroundings  ;  but  how  is  it  possible 
to  account  for  it  on  the  theory  of  large  and,  speaking  comparatively, 

1  De  Vries  (Darwin  and  Modern  Science,  p.  68)  insists  that  correlated  mutations 
are  common.     But  correlation  is  not  the  same  thing  as  co-adaptation. 


THE  ARRIVAL  OF  THE  FITTEST  183 

very  rare  mutations  ?  No  real  attempt  has  been  made  to  sur- 
mount all  these  difficulties.  Merely  because  some  mutations  have 
been  observed  it  has  been  assumed  that  all  evolution  proceeds 
by  steps  and  not  up  a  smooth  incline.  Merely  because  some 
mutations,  the  inheritance  of  which  is  alternative,  are  comparatively 
stable,  it  has  been  assumed  that  all  mutations  are  absolutely  stable. 
Merely  because  fluctuations  cannot  be  fixed  by  a  short  course  of 
experimental  selection,  it  is  assumed  that  they  cannot  be  fixed  by 
the  age-long  selection  of  nature.  Merely  because  varieties  which 
have  been  evolved  under  artificial  selection  display  when  crossed 
alternative  reproduction  in  widely  divergent  characters,  it  has  been 
thought  that  all  inheritance  is  alternative.  All  these  inferences  are 
illegitimate  expansions  of  single  inductions — illegitimate,  because 
there  has  been  no  rigorous  deductive  inference  of  consequences, 
and  no  appeal  to  reality  for  confirmation. 

303.  It  is  not  to  be  maintained,  of  course,  that  no  mutation  has 
ever  been  selected  by  nature.     It  is  maintained  merely  that  species 
are   so  accurately  adapted  to  their  environments,  including  one 
another,  and  that  their  structures — nervous,  circulatory,  alimentary, 
bony,  muscular,  glandular,  etc. — are  so  closely  co-adapted  that  a 
favourable  mutation  must  be  an  extraordinarily  rare  thing — so  rare 
that  as  factors  in    evolution   mutations  are  negligible.      We  are 
told  sometimes  that,  whilst  Natural  Selection  may  account  for  the 
survival  of  the  fittest,  it  does  not  account  for  the  arrival  of  the 
fittest.     This  jingle  of  words  implies,  of  course,  that  fluctuations  are 
too  small  to  have  selection  value.1       But  we   shall   see  in  later 
chapters,  when  we  study  the  recent  evolution  of  man,  who,  as  I 
say,  is  the  wild  type  we  are  best  able  to  observe,  that  fluctuations 
have  so  real  a  survival  value  that,  according  as  men  fluctuate  favour- 
ably or  unfavourably — solely  on  that  account — they  survive  and  see 
their  grandchildren,  or  perish  in  youth.     The  arrival  of  the  fittest, 
owing  to  the  necessary  co-adaption  of  parts  and  species,  is  an  im- 
mensely greater  difficulty  for  the  mutationist  than  for  the  selectionist 

304.  We  have  noted  that  living  beings  are  bundles  of  adapta- 
tions.    No  phenomenon  of  life  is  more  universal  than  the  occurrence 
of  fluctuations.     Presumably,  therefore,   fluctuating  variability   is 
an  adaptation,  and  a  highly  useful  character.      It  has  a  function. 
Mutationists — at  any  rate  many  of  them — admit,  for  example  in 
the  case  of  trotting-horses,  that  fluctuations  are  transmissible  to 
some  extent,  and  may  be  the  sources  of  some  temporary  evolution. 
But  we  are  asked  to  believe  that  opulent  but  parsimonious  nature, 

1  See  §'4826  (footnote). 


1 84  THE  MUTATION  THEORY 

that  prolific  creator  of  wonderful  adaptations,  has  so  contrived  that 
directly  this  evolution  becomes  of  importance  as  a  factor  in  survival 
it  is  brought  to  a  standstill ;  the  species  must  wait  for  that  rarest 
of  phenomena,  an  adaptive  mutation. 

305.  To    sum    up,   the    Mendelian    doctrine — the   notion   that 
inheritance  is  alternative,  that  allelomorphs  meet  in  the  zygote  but 
separate    in  the   descendant  gametes — is  founded  on  experiment. 
It  has  not  been  tested  by  experiment.     Experimental  tests  reveal 
the  existence  of  blending  when  natural  varieties  are  crossed,  and 
of  latent  characters  when  artificial  varieties  are  crossed,  and,  there- 
fore, in  both  cases  negative  the  hypothesis  of  segregation.     The 
attempt  to  explain  away  latent  traits  by  the  hypothesis  of  factors 
and  determiners  is  founded  on  a  pure  guess  which  is  negatived  by 
their  occurrence  in  pure-bred  varieties.     The  mutation  hypothesis 
can  hardly  even  be  said  to  be  founded  on  experiment ;  for  most 
mutations  have  been  simply  observed.     In  any  case  the  notion  that 
evolution  depends  solely  or  mainly  on  mutations  neither  has,  nor  can 
be  tested  experimentally  ;  for  we  can  never  be  sure  that  we  have 
correctly  reproduced  '  natural '  conditions,  nor  can  we  continue  our 
experiments  long  enough.     But  both  the  Mendelian  and  Mutation 
hypotheses  may  be  tested  by  the  ordinary  and  necessary  scientific 
procedure  of  making  a  rigorous  deductive  inference  of  consequences 
and  appealing  to  reality  for  confirmation.     In  neither  case  have 
their  supporters  applied  the  test.     Both  hypotheses,  therefore,  are 
"  awful  examples  "  of  all  that  scientific  thinking  should  not  be. 

306.  The  reader  perceives  that  the  traits  which  mainly  dis- 
tinguish the  experimental  biological  school  from  all  other  schools 
in  all  other  branches  of  science  are  its  self-imposed  restrictions  in 
observing  and  thinking — restrictions  which  render  it  impossible  for 
the  experimental  worker  to  prove  his  hypotheses  to  the  satisfaction 
of  other  people,  or  for  others  to  disprove  them  to  his  satisfaction. 
With  the  exception  of  data  furnished  by  some  few  human  abnor- 
malities and  the  like,  almost  the  whole  of  the  facts  used  have  been 
drawn  from  experiment,  and  none  of  them  have  been  used  to  test 
the  thinking.    We  read  occasionally  in  the  literature  of  that  school 
such  pronouncements  as,  "  Evolution  became  the  exercising  ground 
of  essayists.  .  .  .  Genetic  experiment  was  first  undertaken,  as  we 
have  seen,  in  the  hope  that  it  would  elucidate  the  problem  of 
species.  .  .  .  The  time  has  now  come  when  appeals  for  the  vigorous 
prosecution   of  this  method    should    rather    be    based    on    other 
grounds." l     "  The  time  is  not  ripe  for  the  discussion  of  the  origin 

1  Bateson,  Mendel's  Principles  of  Heredity,  pp.  3-4. 


THE  ESSAYISTS  185 

of  species.  With  faith  in  evolution  unshaken — if  indeed  the  word 
faith  can  be  used  in  application  to  that  which  is  certain — we  look 
on  the  manner  and  causation  of  adapted  differentiation  as  still 
wholly  mysterious."1  The  "essayists"  were  such  men  as  Darwin, 
Wallace,  Huxley,  Ray  Lankester,  and  Thiselton-Dyer  in  England, 
Weismann  and  Osborn  abroad.  Some  of  them  did  not  them- 
selves experiment ;  but  it  is  possible  to  think  correctly,  even  about 
experiments,  without  first  having  personally  controlled  the 
breeding  operations  of  rabbits  and  guinea-pigs.  Moreover,  the 
quantity  of  data  already  in  hand  to  which  Darwin's  work  called 
attention  was  so  large  as  to  occupy  more  than  sufficiently  the  time 
of  the  most  industrious  thinker  who  was  capable  of  dealing  with 
complex  material.  The  method  of  the  essayists  was  not,  as  might 
be  gathered  from  the  words  I  have  quoted,  to  neglect  experimental 
work.  Some  of  them  constantly  experimented.  On  the  contrary, 
their  method  was  to  use,  not  only  the  experimental,  but  all  the 
materials  at  their  command,  and  to  test  their  thinking  in  every 
way  possible.  Therefore  their  writings  necessarily  took  the  form 
of  "essays."  It  is  only  when  we  use  isolated  fragments  of  evidence 
and  guess  about  it  that  we  are  able  in  biology  to  avoid — if  that  be 
a  merit — even  the  appearance  of  reasoning. 

307.  The  writings  in  which  the  Mendelian  and  mutation 
hypotheses  are  formulated  are  as  much  essays  as  those  which  are 
denounced  as  such.  They  are  distinguished  from  the  latter  only 
by  very  novel  conceptions  concerning  the  nature  of  science  and  of 
logical  proof.  It  would  not  be  surprising  were  a  section  of  the 
general  public,  which  has  only  the  vaguest  ideas  as  to  what  science 
is  and  how  it  has  been  created,  deluded  into  the  belief  that 
experiment  is  an  invariable  accompaniment  of  special  accuracy 
in  scientific  observation  and  thought.  For  experiment  is  an 
instrument  which  has  been  employed  almost  solely  by  men  of 
science.  But  that  a  whole  school  of  biologists  should  entertain 
that  notion,  apparently  in  complete  unawareness  that  the  question 
as  to  what  constitutes  evidence  and  what  proof  has  been  elabo- 
rately discussed  by  some  of  the  greatest  thinkers  of  the  past,  is 
certainly  very  remarkable.  It  is,  perhaps,  conceivable  that 
experimental  workers  are  right  in  neglecting  patent  facts  and  tests 
for  thinking ;  but  I  do  not  think  I  can  be  wrong  or  prejudiced 
when  I  insist  that  so  great  a  departure  from  established  scientific 
usage  should  be  vindicated  by  at  least  some  formal  attempt  at 
justification.  But  never  yet  has  this  been  done.  As  matters 
1  Bateson,  Darwin  and  Modern  Science,  p.  99. 


1 86  THE  MUTATION  THEORY 

stand,  appeals  that  we  shall  vigorously  prosecute  the  experimental 
method  and  abstain  from  controversy  mean  little  more  than  that 
we  shall  ignore  all  material  gathered  otherwise  than  by  experiment, 
and  abstain  from  testing  the  correctness  of  guesses — that  we  shall 
permit  biology  to  become  a  tumbling-ground  for  irresponsible 
whimsies.  Declarations  that  the  time  is  not  ripe  for  the  discussion 
of  the  origin  of  species,  and  that  the  manner  and  causation  of 
adapted  differentiation  are  still  wholly  mysterious,  imply  nothing 
more  than  that  it  has  been  found  impossible  to  bring  the  Mendelian 
and  mutation  hypotheses  into  accord  with  the  fact  that  living  beings 
exist  and  are  fitted  to  their  surroundings.  The  denial  (based  on 
the  supposed  inutility  of  structures,  the  uses  of  which  have  not 
been  ascertained)  that  living  beings  are,  in  a  wonderfully  complete 
degree,  adaptational  forms,  has  precisely  the  same  origin. 


CHAPTER    IX 
THE   FUNCTION   OF   SEX 

Most  Mendelian  characters  are  sexual  characters — The  parallel  between 
Mendelian  and  sexual  characters — It  has  been  said  that  the  inheritance  of  sexual 
characters  is  Mendelian — The  truth  is  that  the  inheritance  of  Mendelian  char- 
acters is  sexual — The  function  of  sex  if  (i)  the  Mendelian  hypothesis  is  true, 
(2)  if  the  mutation  hypothesis  is  true,  (3)  if  evolution  is  founded  on  fluctuations  and 
inheritance  is  blended. 


M 


308.  ~|\  yfUTATIONS  and  Mendelian  reproduction  are 
realities.  If,  then,  the  organism  is  a  bundle  of 
adaptations,  and  evolution  builds  on  fluctuating 
variations  which  blend,  how  is  their  presence  to  be  accounted  for  ? 
We  have  considered  several  great  problems  of  heredity  and 
evolution,  for  example  the  nature  of  the  distinction  between 
classes  of  characters,  the  mode  in  which  the  individual  develops, 
the  mode  in  which  species  evolve,  the  causation  of  variations, 
and  the  like.  Obviously  the  mutation  hypothesis  is  concerned 
with  none  of  these  except  evolution.  But  evolution  is  merely 
another  name  for  the  adaptation  which  results  from  progression 
and  retrogression  ;  and,  as  we  have  seen,  it  is  not  believable  that 
mutations,  which  occur  only  rarely  and  which,  speaking  practically, 
are  never  adaptive,  can  have  furnished  the  materials  for  the 
multitudinous,  the  perpetually  changing,  the  infinitely  complex 
and  delicate  adjustments  of  living  beings.  We  are  driven,  then, 
to  the  conclusion  that  they  are  nothing  other  than  abnormalities, 
extreme  variations  which  arise  only  because  evolution  (and  there- 
fore the  regulation  of  variations)  is  never  perfect — just  that  class  of 
variations  which  nature  checks  by  the  weeding  out  of  the  exception- 
ally variable  individuals,  but  which  human  breeders  encourage  and 
preserve,  that  class  on  which  surgeons  expend  the  resources  of  their 
art  to  eliminate  in  the  individual  but  to  perpetuate  in  the  race. 

309.  We  have  to  delve  deeper  before  we  can  account  for  the 
Mendelian  phenomena.  Experimental  workers  assume  that  in 
Mendel's  laws  they  have  acquired  a  master-key  to  all  or  most  of 
the  problems  of  heredity.  But,  if  we  consider  the  question  closely, 
it  becomes  evident  that  Mendel's  laws  are  concerned  with  nothing 

187 


1 88  THE  FUNCTION  OF  SEX 

more  than  the  effect  or  function  of  conjugation)-  Manifestly  they 
have  no  bearing  on  such  problems  as  progression,  retrogression, 
recapitulation,  variability,  the  causation  of  variations,  the  dis- 
tinction between  characters,  and  the  rest  we  have  discussed. 
They  merely  attempt  to  describe  the  way  in  which  parental 
characters  are  distributed  amongst  offspring  and  descendants 
under  conditions  of  conjugation.  To  parthenogenesis  they  do  not 
apply  ;  for  here,  since  no  allelomorphs  meet,  none  can  be  dominant 
or  recessive,  none  can  segregate.  In  fact,  they  apply  to  no 
problem  that  is  presented  in  common  by  parthenogenetic  and 
conjugating  species.  At  any  rate  I  can  think  of  none ;  and  though 
I  have  inquired  industriously  amongst  the  adherents  of  "  the  new 
science  of  genetics,"  I  have  quite  failed  to  secure  enlightenment.2 

310.  It  has  been  said,  indeed,  that  since  "the  rule  that  all 
organisms  pass  through  a  sexual  cycle  at  some  period  of  their 
existence  has  extremely  few  exceptions,"  3  all  problems  of  biology 
are  problems  of  conjugation.     It  would  be  as  reasonable  to  declare 
that,  since  all  organisms  die,  therefore  all  problems  of  biology  are 
problems  of  death.     Such  a  statement  is  merely  equivalent  to  a 
declaration  that  the  universe  is  a   unity,  the  facts  and  laws  of 
which  are  related.     Again,  it  has  been  said,  "  It  is  the  claim  of  the 
Mendelians  that  they  have  discovered  in  certain  cases  some  of  the 
fundamental  characters  of  an  organism — the  units  of  hereditary 
transmission,  which  are  represented  in  the  reproductive  cells  by 
definite  entities  known  as  allelomorphs."  4     But,  obviously,  if  there 
is  no  segregation,  but  merely  patency  and  latency,  the  discovery 
has  not  been  made.     In  this  instance,  also,  it  would  be  well  if  the 
reader  paused  and  asked  himself,  not  whether  Mendelism  solves 
any  problems,  but  whether  it  has  a  conceivable  bearing  on  any 
problem  save  that  of  conjugation — of  sex. 

311.  We  saw  that  individuals  of  sexually  dimorphic  species 
have   two   sets    of    sexual    characters,    one   of    which    is    patent 
and  the  other  latent,  one  of  which  is  dominant  and  the   other 

1  Of  course  every  effect  is  not  necessarily  a  function.  A  function  is  that  which 
bestows  utility.  One  effect  of  sex  is  to  halve  the  possible  number  of  offspring. 
But  no  one  will  believe  that  this  halving  is  the  function  of  sex.  Besides,  nature 
is  able  by  the  selection  of  fertility  to  increase  the  number  of  offspring  produced  by 
a  pair  up  to  any  useful  limit,  and  so  obviate  this  effect.  On  the  other  hand,  if, 
as  Mendelians  suppose,  bi-parental  reproduction  mixes  parental  characters  as 
marbles  are  mixed,  but  leaves  them  otherwise  unchanged,  it  would  seem  we  have 
no  alternative  but  to  suppose  that  such  mixing  is  both  the  effect  and  the  actual 
function  of  sex.  I  think  it  is  impossible  to  imagine  any  other  function. 

8  See,  for  example,  Nature,  3rd  Oct.  1907  to  Jan.  23rd  1908. 

3  R,  H.  Lock,  Nature,  Nov.  I4th,  1907.  4  Op.  cit,,  Nov.  I4th,  1907. 


SEXUAL  AND  MENDELIAN  REPRODUCTION        189 

recessive.  Every  individual  is  in  fact  an  'impure  dominant' 
The  non-sexual  characters,  on  the  other  hand,  are  all  patent. 
When  the  breeding  is  intra-varietal,  as  it  normally  is  in  nature, 
mating  individuals  (apart  from  their  sexual  characters)  differ, 
with  rare  exceptions,  only  to  the  extent .  of  fluctuations,  the  in- 
heritance of  which,  admittedly,  is  blended.  The  exceptions  are 
mutations  which,  like  the  sexual  characters,  tend  not  to  blend,  but 
to  become  patent  or  latent  in  descendants.  We  saw  also  that 
when  natural  varieties,  which  have  arisen  through  the  selection  of 
fluctuations,  cross,  they  tend  to  blend  their  characters ;  but  when 
artificial  varieties,  which  have  arisen  through  the  selection  of  muta- 
tions, cross,  the  reproduction  of  the  characters  in  which  they  differ 
tends  to  be  alternative.  Evidently,  then,  the  mode  in  which  muta- 
tions are  reproduced  by  offspring  and  descendants  presents  a  close 
parallel  to  the  mode  in  which  the  sexual  characters  are  reproduced. 
312.  The  parallelism  between  the  two  sets  of  phenomena,  the 
sexual  and  the  Mendelian,  grows  clearer  the  more  we  study  it. 
We  have  already  noted  many  of  the  likenesses,  but  it  will  be  useful 
to  bring  them  together,  (a)  Of  necessity  some  of  the  sexual  char- 
acters, especially  the  primary  characters,  are  developed  in  distinct 
sets — a  male  set  and  a  female  set — which  are  kept  separate  by 
selection.  Most  of  the  Mendelian  characters,  on  the  other  hand, 
are  developed  indifferently  by  both  sexes.  But  many  characters 
the  functions  of  which  are  sexual  (in  that  they  serve  as  attractions), 
though  not  exclusively  sexual,  are  reproduced  in  the  latter  way ; 
for  example,  colour  of  eyes,  and,  to  some  extent,  colour  of  skin  and 
hair  in  the  intra-varietal  matings  of  man,  and  colour  of  plumage 
and  hair  in  the  inter-varietal  matings  of  many  birds  and  mammals. 
(b}  Sometimes  characters  peculiar  to  one  sex  are  transferred  to  the 
other,  as  in  the  cases  of  the  bony  cranial  protuberance  of  the  Polish 
fowl 1  and  the  plumage  of  the  Sebright  bantam.  Some  Mendelian 
characters  are  transmitted  sexually,  as  colour-blindness  and  haemo- 
philia in  man.  They  would  be  termed  sexual,  not  Mendelian,  were 
they  more  common.  Deaf-mutism  appears  to  furnish  a  further 
connecting  link,  for  the  condition  tends  to  affect  the  males  in  some 
families  and  the  females  in  others.2  Moreover,  the  dominance  and 
recessiveness,  the  patency  and  latency  of  Mendelian  characters 
is  sometimes  affected  by  the  sex  of  the  parents,  the  offspring  of 
reciprocal  crosses  being  unlike.3 

1  Animals  and  Plants,  vol.  i.,  p.  269. 

*  C.  J.  Bond,  British  Medical  Journal,  Oct.  28th  1905. 

3  See  §  264;  see  also  Bateson,  Mendel's  Laws  of  Heredity,  chapter  x. 


THE  FUNCTION  OF  SEX 

313.  (c)  The  alternative  development — the  alternative  patency 
and  latency — of  sexual  characters  is  more  perfect  than  that  of  most 
Mendelian  characters,  but   this   is   only  what   might   have   been 
expected  ;  for  it  has  been  secured  by  selection,  just  as  the  less 
perfect,  or  rather  the  different  alternation  in  aphides,  and  bees  has 
been  similarly  secured,    (d)  When  Mendelian  characters  are  crossed, 
one  of  each  pair  is  usually  the  dominant  in  the  first  hybrid  genera- 
tion.    Thus  colour  is  usually  dominant  over  white  in  mammals 
and  flowers,  whereas  the  contrary  is  the  case  in  poultry.     In  the 
case  of  sexual  characters  one  or  other  alternative  dominates  in  any 
individual.     But   sometimes   the   offspring   of  a    single   pair   are 
wholly  of  one  sex,  a  phenomenon  not  very  rare  in  human  families ; 
whilst,  on  the  other  hand,  in  the  case  of  some  Mendelian  alterna- 
tives, both  types  tend  to  appear  in  the  first  hybrid  generation — for 
example,  normal  and  extra  toes  in  poultry,      (e)  As  might  have 
been  expected  also,  the  sexual  characters  show  a  lesser  tendency  to 
blend  than  Mendelian  characters  ;  but  some  degree  of  blending  is 
not  uncommon  in  the  former,  as  when  women  have  masculine  pelves 
and  partially  bearded  faces.      (/)  The  crossing  of  varieties  may 
bring  to  light  long  dormant  Mendelian  characters — for  example, 
wild-grey  in  mice  and  rabbits ;  it  may  also  reveal  strictly  sexual 
characters  which  have  long  been  latent ;  for  example,  broodiness 
and  sexual  peculiarities  of  plumage  in  fowls ;  and  sometimes  the 
lost   sexual   characters   may   reappear   in   connection  with  traits 
properly   belonging  to  the  opposite  sex.1       (g)  As  Ewart2   and 
others  have  shown,  the  dominance  of  both  sexual  and  non-sexual 
alternative   characters    is    capable   of    being    influenced    by   the 
environment. 

314.  (k)  If  the  characters  of  crossed  varieties  blend  or  are  lost, 
there  is  a  very  general  tendency  to  sterility,  as  is  the  case  when 
natural  varieties  interbreed  ;  but  if  they  alternate  so  that  the  char- 
acters are  unchanged,  as  when  artificial  varieties  cross,  fertility  is 
perfect.     "  We  know  no  Mendelian  case  in  which  fertility  is  im- 
paired." 3     We  have  here  a  very  clear  indication  of  the  parallelism 
between  sexual  and  Mendelian  characters,  for  under  such  conditions, 
as  in  mules,  sexual  characters  also  tend  to  blend  or  be  lost  with  con- 
sequent sterility,    (z)  Mendelian  characters  which  segregate  in  later 
generations  are  sometimes  blended  in  the  first  hybrid  generation — 
for  example,  in  the  case  of  Andalusian  fowls ;   or  there  may  be 
particulate  inheritance  in  the  first  generation  and  more  complete 

i  See  §280.  2  See  §132. 

3  First  Report  of  Evolution  Committee,  p.  148. 


SEXUAL  AND  MENDELIAN  TRAITS  191 

separation  subsequently.1  In  like  manner,  when  varieties  are 
crossed,  a  pseudo-hermaphroditism  is  not  uncommon,  that  is,  the 
1  inheritance  of  male  and  female  characters  is  then  particulate,  the 
separation  into  male  and  female  sets  is  not  preserved ;  there  is  on 
the  contrary  Mendelian  independence  of  characters.  (/)  As  we 
have  seen,  there  is  no  real  segregation  of  Mendelian  any  more 
than  of  sexual  characters.  There  is  only  patency  and  latency. 
(k)  Sometimes  both  alternative  Mendelian  characters,  for  example, 
extra  toe  and  normal  foot  in  poultry,  appear,  like  the  sexual 
characters,  in  the  different  individuals  of  the  first  hybrid  genera- 
tion, and  would  -continue  to  appear  in  each  succeeding  generation 
were  they  like  the  sexual  characters  crossed  in  each  generation. 
(/)  In  other  instances,  the  Mendelian  traits  are  long  latent,  like  the 
sexual  characters  in  aphides ;  but  like  them  reappear  at  length,  as 
in  cases  of  reversion  in  pure-bred  varieties.2  (m)  In  another  pecu- 
liarity, and  that  a  very  striking  and  important  one,  Mendelian 
and  sexual  characters  display  a  suggestive  resemblance.  Both 
are  traits  in  which,  unlike  fluctuations,  the  mating  individuals  are 
strongly  contrasted ;  for  the  Mendelian  characters  are  usually 
mutations  or  characters  which  originated  by  mutation  in  ancestors. 

315.  Plainly,    the    parallel    between    sexual   and    Mendelian 
reproduction    is   very   close.      It   is   so   close   that   experimental 
workers,  though  they  have  not  by  any  means  perceived  all  the 
likenesses,  have  surmised  that  the  inheritance  of  sexual  characters 
accords,  in  many  instances  at  least,  with  Mendel's  laws.3     Indeed, 
they  have  supposed    that   the  inheritance  of  sex   is   merely  an 
example  of  Mendelian   inheritance,4  and  that  continued  investi- 
gation will  eliminate  any  apparent  contradictions  and  anomalies. 
But  another  interpretation  of  the  facts  is  conceivable.    Examine  any 
list  of  Mendelian  characters^  for  example  those  of  poultry  5  or  peas.*  A 
glance  shows  that^  as  a  rule>  the  majority  of  the  items  in  such  a  list  are 
sexual  in  the  sense  that,  as  attractions  or  otherwise^  they  are  concerned 
with  reproduction.     It  is  possible,  then,  that,  so  far  from  it  being 
a  fact  that  the  reproduction  of  sexual  characters  is  an  example  of 
reproduction  of  Mendelian  characters,  the  reverse  may  be  the  case. 

316.  The  question  we  are  now  in  a  position  to  ask  ourselves 
is,  Which  mode  of  reproduction,   the  sexual  or  the   Mendelian, 
contains  the  other  ?    Which  is  a  variety  of  the  other  ?    In  deciding 

1  Inheritance  in  Poultry,  p.  85.  a  See  §  280. 

3  See  Bateson,  Mendel's  Laws  of  Heredity,  chapter  x. 

4  See  Castle,  Heredity  oj  Sex. 

6  See  §  288.  •  See  §  257. 


192  THE  FUNCTION  OF  SEX 

this  problem,  we  must  bear  in  mind  that  sexual  reproduction  is 
almost  universal;  whereas,  to  judge  by  facts  that  have  been 
actually  observed,  not  merely  imagined,  Mendelian  reproduction 
is  one  of  the  rarest  things  in  nature.  Speaking  practically,  it 
occurs  only  when  mutations  are  reproduced ;  and  all  the  evidence 
indicates  that  mutations  occur  relatively  seldom,  and,  even  then, 
are  very  seldom  preserved,  except  when  the  selection  is  artificial. 
Mendelian  reproduction,  therefore,  is,  in  effect,  unknown  in 
normal — that  is,  z>z/nz-varietal — breeding.  Natural  varieties  very 
rarely  cross,  and  only  rarely  display  Mendelian  traits  when  man 
crosses  them.  Such  traits  are  common  only  when  artificial 
varieties,  in  which  mutations  have  been  accumulated  by  man,  are 
crossed  by  man.  They  seem  common  to  experimental  workers 
only  because  the  materials  for  thought  to  which  they  have  limited 
themselves  have  been  obtained  almost  exclusively  in  this  latter 
way.  I  think,  therefore,  that  no  one  who  has  been  accustomed 
to  found  his  judgments,  not  on  the  exception  but  the  rule,  will 
hesitate  to  conclude  that  Mendelian  reproduction  is  a  variety  of 
sexual  reproduction,  and  that  the  converse  is  as  absolutely  untrue 
as  if  we  had  declared  that  mammals  are  a  variety  of  dogs. 

317.  If  we  found  our  judgments  on  verified  evidence  alone, 
the  conclusion  seems  irresistible  that  Mendelian  '  inheritance '  is 
a  human  creation,  and  that  the  right  interpretation  of  the  facts 
appears  to  be,  that  nature  treats  mutations,  when  man  interferes 
and  presents  them  to  her,  as  sexual  characters.  She  is  not  a 
conscious  selecting  agency,  and  they  resemble  the  sexual  characters 
and  differ  from  the  fluctuations  which  she  normally  meets,  in  that 
they  constitute  wide  differences  between  mating  individuals.  But 
her  treatment  of  them  is  more  or  less  uncertain ;  hence,  as 
compared  to  sexual'  traits,  their  imperfect  alternation  and  their 
tendency  to  blend  in  greater  or  lesser  degree.  It  appears,  then, 
that  Mendelian  characters  are  nothing  other  than  non-sexual  or 
semi-sexual  characters  abnormally  reproduced  in  the  mode  that 
sexual  characters  are  normally  reproduced.  It  follows  that  experi- 
mental workers  have  been  engaged  in  investigating,  not  heredity 
in  general,  not  even  the  function  of  sex,  but  only  certain  anomalies 
of  sexual  reproduction  which  occur  under  conditions  of  artificial 
selection  and  crossing.  They  are  the  unhappy  victims  of  a  vast 
practical  joke  unconsciously  played  by  the  human  breeder. 

"  The  earth  hath  bubbles,  as  the  water  has, 
And  these  are  of  them." 1 

^'Macbeth,"  i.  3. 


.     .  . 

MENDELISM  AND  SEX  193 

They  furnish  examples  of  the  disasters  which  tend  to  befall  us 
when  we  limit  the  area  whence  we  draw  the  materials  for  thought, 
and  fail  to  test  our  thinking  in  every  way  possible,  when,  in  fact, 
our  attitude  is  sectarian,  not  scientific. 

318.  The    question    of    the    relation    between    sexual    and 
Mendelian   characters   cannot,  however,    be   disposed    of  in   this 
summary  fashion.    At  any  rate,  since  the  reader  may  still  consider 
it  a  matter  of  opinion  whether  the  inheritance  of  sexual  characters 
is  Mendelian  or  the  reproduction  of  Mendelian  characters  sexual, 
it  ought  not  to  be  so  disposed  of.     It  is  necessary  to  make  the 
usual  deductive  inference  of  consequences,  and  then  to  compare 
these  consequences  with  reality.     It  is  an  indisputable  truth  that 
living   beings    exist   and   have   undergone  evolution.      Does  the 
hypothesis  that  the  inheritance  of  characters,  including  the  sexual, 
is  Mendelian  accord  with  this  truth,  or  is  it  incompatible  with  it? 
Or,  on  the  contrary,  does  the  hypothesis  that  inheritance  tends 
to  be  blended,  and  that    Mendelian  traits  are  abnormalities  of 
sexual    reproduction    introduced   by   man,    accord   with   it?      In 
brief,  we  have  now  to  investigate   the   function   of  conjugation, 
of  sex. 

319.  If  the  Mendelian  theory  is  true,  the  effect  and,  therefore, 
presumably,   the   function   of    conjugation    is    to    mix    parental 
characters  as  marbles  are  mixed,  not  to  blend  them  as  colours 
are  blended.     Now  suppose,  for  example,  that  a  tall  man  mates 
with  a  short  woman  and  offspring  are  born  to  them.     This  means 
that  both  parents  have  been  so  well  adapted  to  the  environment, 
and  their  characters  so  well  co-adapted  to  one  another,  that  they 
have  been    enabled   to   survive   till  they   were    mature.       But  if 
characters  are  transmitted  independently  of  one  another,  the  '  tall ' 
and    '  short '    characters   of    the    parents   will    be   mixed   in    the 
offspring.     This  is  not  what  happens  in  nature.     It  is  not  even 
what  happens  when  artificial  varieties  are  crossed  by  man  ;  for 
only  a  very  few  of  the  characters  (e.g.  colour  of  plumage  and  extra 
toe)  of  such  varieties  have  been  established  by  him  through  the 
selection  of  mutations.     But  it  is  what  is  implied  in  the  Mendelian 
doctrine.     It  must  be  remembered  that  tallness  and  shortness  in 
human  beings  and  other  animals  depend,  not  on  a  single  character 
like  internodal  length  in  the  pea,  but  on  a  multitude  of  structures, 
all  of  which  are  supposed  to  be  inherited  independently  of  one 
another.1     Moreover,  relative  tallness  and  shortness  are  not  neces- 
sarily fluctuations,  for  there  are  stable  tall  and  short  human  races 

1  Bateson,  Mendel's  Principles  of  Heredity,  p.  209. 

'3 


194  THE  FUNCTION  OF  SEX 

which,  as  it  happens,  are  able  to  cross  successfully.  On  the 
Mendelian  theory,  however,  the  effect  of  bi-parental  reproduction 
should  be  calamitous  ;  and  one  is  left  to  wonder  how  it  happened 
that  this  form  of  reproduction  replaced  parthenogenesis,  in  which 
such  a  disastrous  mingling  of  incongruous  elements  would,  at 
least,  not  occur.  Moreover,  self-fertilization  is  not  uncommon,  and 
is  a  product  of  evolution.  Here,  since,  almost  invariably,  only 
like  characters  meet,  there  can  be,  speaking  practically,  no  mixing 
of  unlike  allelomorphs,  and  we  must  suppose  that  conjugation 
— that  sex,  which  has  burdened  living  beings  with  so  many 
characters — has  no  function  whatever.  It  is  surely  not  surprising, 
then,  that  Mendelians,  conscious  of  the  tangle,  should  feel  moved 
to  declare  that  they  "  look  on  the  manner  and  causation  of  adapted 
differentiation  as  still  wholly  mysterious,"  and  that  "we  can 
profitably  reject,  as  I  believe,  much  of  the  theory  of  Natural 
Selection,  and  more  especially  the  idea  that  adaptations  have 
arisen  because  of  their  usefulness."1 

320.  On  the  other  hand,  if  the  mutation  theory  as  conceived 
by  Professor  de  Vries  is  true,  that  is,  if  the  variations  on  which 
progressive  evolution  is  founded  are  large  discontinuous  mutations, 
and  if  mutants  tend  to  be  sterile  when  crossed  with  the  parent 
type,  or  if  fertile,  to  have  offspring  which  blend  the  parental  char- 
acters, then,  again,   one  is  left  to  wonder  at  the   extraordinary 
function  assigned  by  implication  to  sex.     When  reproduction  is 
parthenogenetic,  useful  mutations,  if  they  occur,  have  an  excellent 
chance  of  surviving.     But  when  reproduction  is  bi-parental,  they 
can  very  rarely,   if  ever,  escape  being  lost   through  sterility,  or 
swamped  through  blending.     According  to  this  hypothesis,  there- 
fore, it  would  appear  that  the  function  of  sex  is  to  render  nature 
powerless  to  produce  adaptive  changes.    And  yet  we  must  suppose 
sex  to  have  been  evolved  by  nature.     In  this  case  also  how  shall 
we  account  for  the  occurrence  of  self-fertilization  ? 

321.  Examine  now  the  theory  that  evolution  proceeds  through 
the  constant  selection  of  ' continuous,'  'normal,'  or  'fluctuating' 
variations,  the  inheritance  of  which  is  blended.2     As  we  have  seen, 

1  See  §  306. 

*  The  term  '  blended/  with  the  meaning  given  it  in  the  present  work,  is  not 
altogether  correct ;  but  it  is  convenient.  It  is  used  in  contradistinction  to 
'  alternative  '  and  includes  all  shades  of  blending  from  an  equal  mixture  of  parental 
characters  to  an  exclusive  reproduction  of  the  character  of  one  parent  with  total 
loss  of  the  character  of  the  other.  Exclusive  inheritance  in  this  sense  differs 
from  dominance  in  that  the  former  implies  the  complete  loss  of  the  character  of 
one  parent,  whereas  the  latter  implies  only  its  latency.  To  the  Mendelian 


THE  BLENDING  OF  PARENTAL  TRAITS  195 

every  species  which  is  sexually  dimorphic,  possesses  two  kinds  of 
characters.      In   some  characters    parents   resemble  one   another 
closely ;  that  is,  they  differ  normally  only  to  the  extent  of  fluctua- 
tions.    The  inheritance  of  these  characters  is  blended.     In  other 
characters  parents  differ  so  widely  that,  did  we  not  know  them  to 
be  male  and  female,  we  should  suppose  them  to  belong  to  different 
species.     The  inheritance  of  these  larger  differences  is  apparently 
alternative.     Really  it  is  blended ;  only  the  reproduction  is  alterna- 
tive ;  for  since  parents  transmit  their  characters  through  children 
of  the  opposite  sex  to  grandchildren  of  the  same  sex,  we  know 
that,  though  every  individual  possesses  only  one  set  of  non-sexual 
characters,  he  possesses  two  sets  of  sexual  characters,  one  of  which 
is  patent  and  the  other  latent.     If,  then,  similar  characters  blend 
(e.g.  the  ears  of  one  parent  with  the  ears  of  the  other,  and  so  on), 
there  can  be  no  doubt,  in  the  case  of  the  sexual  traits,  that  the 
patent  male  characters  of  the  father  blend  with  the  latent  male 
characters  of  the  mother,  while  the  paten \.  female  characters  of  the 
latter  blend  with  the  latent  female  characters  of  the  former.     The 
child,  however,  presents  a  deceptive  appearance  of  inheriting  only 
one  set  of  characters  in  which  there  is  no  blending.     Abnormally, 
the  patent  sexual  traits  of  the  one  sex  blend  with  those  of  the 
other  as  in  many  of  the  so-called  hermaphrodites  of  sexually  di- 
morphic species.     Except  in  the  case  of  mutants,  which  in  nature 
only  very  rarely  survive  and  have  offspring,  all  the  larger  differ- 
ences  between   mating    individuals   are  sexual.        But    in   some 
characters  mating   individuals   do   not   differ  widely.      Thus  the 
coloration  of  the  male  and  female  may  be  similar.     The  inherit- 
ance of  such  characters  is  admittedly  blended.    In  parthenogenesis 
there  is  neither  latency  nor,  of  course,  blending.      Latency  and 
blending  are  phenomena  of  bi-parental  reproduction  only. 

322.  The  only  real  exception  to  blended  inheritance  that  I  can 
think  of  occurs  when  a  mutation  first  arises,  If  the  mutant  (the 
individual  that  has  mutated)  be  crossed  with  a  normal  individual 
the  mutation  may  be  diminished,  in  which  case  the  inheritance  is 
blended  ;  or  it  may  be  quite  eliminated,  leaving  no  representative 
in  the  germ-plasm,  in  which  case  there  occurs  that  extreme  form 
of ' blended '  inheritance  which  we  have  termed  exclusive ;  or  the 
mutation  may  be  present  in  the  offspring  unchanged  by  conjuga- 
exclusive  inheritance  is  identical  with  gametic  purity,  but,  as  we  have  seen,  it  is 
certain  that  gametic  purity  does  not  occur  when  '  inheritance  '  is  alternative.  In 
such  cases  we  have  only  alternative  development.  The  term  prepotent  as  applied  to 
a  parent,  implies  that  his  or  her  character  predominates  in  the  blend  in  any  degree 
up  to  an  exclusive  inheritance.  To  the  Mendelian  prepotence  implies  dominance. 


196  THE  FUNCTION  OF  SEX 

tion  in  a  patent  or  latent  condition,  in  which  case  there  is  no 
blending  in  that  generation.  In  subsequent  generations  there  is 
blending  if  descendants  of  the  mutants  interbreed,  for  they  will 
have  the  character  in  a  patent  (dominant)  or  latent  (recessive) 
condition.  It  is  not  to  be  supposed,  however,  that  mutations  are 
reproduced  unaltered  in  offspring  and  descendants.  Presumably, 
like  other  characters,  they  are  subject  to  fluctuating  variations,  of 
which  the  general  trend  is  retrogressive.  They  disappear,  there- 
fore, in  time  by  sudden  mutation,  or  probably  more  usually  by 
gradual  retrogression,  unless  preserved  by  selection.  We  have  no 
reason  to  suppose  that  they  are  less  liable  to  retrogression  when 
latent  than  when  patent.  No  doubt,  numbers  of  latent  characters 
have  persisted  through  many  generations  in  domestic  species  ;  but, 
speaking  comparatively,  all  domestic  species  are  of  recent  origin, 
and  the  retrogression  of  some  useless  patent  characters  (e.g.  limbs 
when  they  have  become  useless)  is  very  slow.  Nature  is  parsi- 
monious of  her  materials  ;  it  is  improbable,  therefore,  that  the 
germ-plasm  is  burdened  for  ever  with  useless  dormant  characters. 
At  any  rate,  there  is  not  an  iota  of  evidence  that  it  is  so  burdened. 
An  interesting  point  in  connection  with  latent  traits  is  the  reap- 
pearance in  offspring  of  numerous  narrow,  rather  faint  stripes  when 
the  horse,  which  has  no  patent  stripes,  is  crossed  with  the  Burchell 
zebra,  which  has  a  few  broad  ones.  This  is  the  most  ancient 
latent  character  known  to  me.  It  is  commonly  believed  that  the 
narrow  stripes  are  due  to  reversion  to  a  common  ancestor.  This 
may  or  may  not  be  true ;  but  it  does  not  follow  that  the  dormant 
trait  is  carried  by  both  species.  Dormant  traits  are  practically 
unknown  in  natural  varieties  such  as  the  zebra ;  and  horses,  even 
when  pure  bred,  sometimes  display  traces  of  stripes.  It  is  pro- 
bable, therefore,  that  the  horse  is  the  carrier  of  them,  that  they 
were  rendered  dormant  in  the  ancestry  by  the  artificial  selection  of 
mutations,  and  that  they  have  grown  faint  through  retrogression. 

323.  Offspring  vary  'spontaneously'  from  their  parents  in  two 
ways.  First,  they  blend  parental  characters,  and  so  differ  from 
both  parents  ;  or,  if  there  is  exclusive  inheritance,  they  differ  from 
one  parent.  Second,  they  differ  from  both  parents  otherwise 
than  by  blending.  With  this  latter  sort  of  spontaneous  variations 
we  have  already  dealt.1  We  have  to  consider  the  variations 
which  result  from  blending.  Suppose,  now,  to  choose  a  homely 
example,  a  man  with  an  exceptionally  broad  nose  mates  with  a 
woman  with  an  exceptionally  high  nose.  Then,  if  the  result  be 

1  See  chapter  v. 


BLENDING  IMPLIES  RETROGRESSION  197 

a  blend,  the  offspring  approach  the  ordinary  specific  type  more 
nearly  than  either  parent ;  that  is,  there  is  retrogression  or 
*  regression  '  as  regards  the  progressive  variations  of  both  parents 
— a  retrogression  towards  the  specific  mean.  Again,  suppose 
there  is  exclusive  inheritance,  so  that  the  peculiarity  of  one  parent 
is  entirely  lost.  We  noted  that  this  very  often  happened  in  the 
case  of  those  numerous  small  redundancies,  those  small  progressive 
variations  which  offspring  invariably  display.1  Here,  again,  there 
is  return  to  the  specific  type  and  retrogression.  When  offspring 
inherit  exclusively  from  the  progressive  parent,  there  is,  of  course, 
no  retrogression  ;  but  this,  as  proved  by  the  general  tendency  to 
retrogression,  happens  comparatively  infrequently,  and,  in  any 
case,  there  is  no  progression. 

324.  Blended    inheritance,    therefore,    nearly   always    implies 
retrogression  when  parents  differ.     The  characters  in  which  they 
differ  tend  to  be  lost,  wholly  or  partially,  within  the  limits  of  the 
difference.      It    never   implies   progression.      When    progression 
occurs,  it  is   due,  not  to   blending,   not   to   the   intermixture  of 
parental  germ-plasms,  but  to  that  spontaneous  variability  which 
is  present  in  all  forms  of  life,  including  parthenogenctic  types. 
Notwithstanding  all  that  has  been  written  on  the  subject,  there  is 
absolutely  no  evidence  that  sex  is  ever  a  source  of  progressive 
variations.     Whenever  we  are  able  to  trace  its  influence  clearly, 
blending  (i.e.  retrogression)  is  what  we  observe.     It  is  true  that 
cross-breeding  may  reveal  latent  characters  in  a  domestic  species. 
But  this  apparent  progression  is  never  real.     Indeed,  it  frequently 
implies  retrogression.2      Again,  when  varieties   are   crossed   and 
their  constitution  'broken,'  as  it  has  been  termed,  the  increased 
variability  which  has  been  said  to  occur  in  descendants  may  well 
be  due  to  alteration,  through  retrogression,  of  that  tendency  to 
vary  only  within  narrow  limits,  which  was  imposed  by  Natural 
Selection  on  both  varieties  after  they  became  adapted  to  their 
surroundings — to  a  return  to  that  condition  of  wider  variability 
which  was  imposed  on  them  while  they  were  becoming  adapted. 
Varietal  crossing,  however,  is  a  rare  phenomenon  in  nature.     It  is 
one   of  the  abnormalities  which  especially   distinguish    artificial 
breeding. 

325.  The    function    of    sex,    therefore,    is    to    bring    about 
retrogression.      But   this    retrogression    does    not  occur   at   hap- 
hazard.    On  the  contrary,  sex,  a  principal  source  of  retrogression, 
does  its  work  with  as  much  discrimination  as  Natural  Selection, 

lSee  §  194.  a  See§  189. 


198  THE  FUNCTION  OF  SEX 

the  sole  source  of  progression.  For  example,  to  choose  another 
homely  instance,  suppose  a  human  race  inhabits  a  region  where 
malaria  is  prevalent,  but  where  tuberculosis  and  measles  are 
absent.  Then  offspring  will  vary  from  their  parents,  favourably 
and  unfavourably,  with  respect  to  all  three  diseases.  In  other 
words,  they  will,  as  compared  to  the  parents,  be  more  resistant 
or  less  resistant  to  each  disease — more  or  less  able  to  survive  if 
exposed  to  it.  It  does  not  follow,  however,  that  an  individual 
who  has  varied  favourably  as  regards  malaria,  will  also  have 
varied  favourably  as  regards  tuberculosis,  measles,  or  any  other 
disease.  Since  malaria  is  present,  those  who  have  varied  un- 
favourably in  relation  to  it  will  be  eliminated,  while  those  that 
have  varied  favourably  will  be  preserved.  Like  will  mate  with 
like,  and  therefore  little  or  no  retrogression  caused  by  blending 
will  occur  to  check  progression  caused  by  Natural  Selection.  On 
the  other  hand,  the  progressive  variations  with  respect  to  tuber- 
culosis and  measles  will  be  mere  useless  redundancies.  Since 
there  will  be  no  elimination  of  those  that  vary  unfavourably, 
unlike  individuals  will  mate.  The  result  will  be  retrogression.1 
Apply  this  reasoning  to  all  the  characters  of  the  individual,  and 
the  function  of  sex  becomes  apparent.  Natural  Selection  preserves 
or  causes  progression  in  useful  characters  by  eliminating  the 
individuals  that  do  not  possess  them  in  sufficient  degree.  On  the 
other  hand,  sex,  a  product  of  evolution  through  Natural  Selection, 
automatically  eliminates  useless  characters,  but  without  eliminating 
the  individuals  that  possess  them. 

326.  The  fact  that  races  undergo  protective  evolution  only 
1  When  two  dwarf  breeds  of  dogs  are  crossed  the  offspring  tend  to  be  larger 
than  either  parent.  This  would  seem  to  indicate  progression  as  a  result  of  crossing. 
But  such  breeds  have  resulted  from  the  artificial  selection  of  mutations.  In  them, 
presumably,  the  larger  size  is  latent.  Again,  inbred  artificial  varieties  tend  to  be 
delicate  ;  and  Darwin  noted  that,  when  two  such  varieties  are  crossed,  the  result 
is  often  an  increase  of  health  and  vigour.  It  seems  not  unreasonable  to  suppose 
that  the  apparent  progression  is  really  due  to  retrogression.  Nature  eliminates 
unfavourable  variations  in  all  directions  in  evolving  varieties.  But  man,  devoting 
his  attention  exclusively  to  one  or  two  points  (e.g.  speed  in  race-horses,  size, 
shape,  and  colour  in  flowers),  neglects  or  cannot  perceive  others  which,  though 
unfavourable,  are  not  eliminated  by  selection  because  the  individuals  are  pro- 
tected, nor  by  conjugation  because  the  individuals,  being  inbred,  are  much  alike. 
Crossing  unites  unlike  individuals  and  so  eliminates  the  unfavourable  redund- 
ancies ;  for  example,  it  tends  to  remove  the  traits  that  cause  '  delicacy  '  and  so  to 
restore  the  pristine  vigour.  It  performs  that  which  it  is  the  function  of  conjugation 
to  perform.  If  this  interpretation  be  mistaken  we  have  no  alternative  but  the 
hypothesis  of  rejuvenescence.  It  should  be  noted  that  the  traits  that  man  con- 
sciously selects  are  usually  mutations.  But  those  which  he  unconsciously  selects 
(e.g.  *  delicacy')  are  usually  fluctuations. 


THE  EVOLUTION  AGAINST  DISEASE  199 

against  the  diseases  to  which  they  are  exposed  is,  I  conceive, 
clear  proof  that  the  organic  world  has  not  arisen  by  mutations 
which  are  permanent  and  which  therefore  nothing  but  selection 
can  eliminate.  We  shall  see  in  the  next  section  of  the  present 
volume  how  great  that  evolution  has  been,  how  closely  it  adjusts 
each  variety  to  its  special  environment,  and  how  laden  it  is  with 
momentous  consequences.  Now,  since  all  races  evolve  against  all 
the  diseases  to  which  they  are  exposed,  it  is  evident  that  favour- 
able variations  against  every  disease  occur  in  every  race.  Unless 
disease  miraculously  evokes  these  variations,  they  are  spontaneous, 
and  therefore,  unlike  the  evolution  which  results  from  their  selec- 
tion, not  dependent  on  the  presence  of  the  disease.  Either  they 
are  fluctuations  which  retrogress  in  the  absence  of  selection,  or 
they  are  mutations  which,  it  is  said,  only  selection  can  eliminate. 
If  experimental  workers  are  right  and  they  are  mutations,  then, 
when  a  variation  which  increases  the  power  of  resisting  a  disease 
occurs  in  a  country  in  which  the  disease  is  not  present,  it  will  not 
be  eliminated  by  selection,  for  it  will  be  a  harmless  character. 
Since  such  variations  are  spontaneous  they  will  occur  as  abundantly 
when  the  disease  is  absent  as  when  it  is  present.  If,  then,  evolu- 
tion is  by  mutation,  how  does  it  happen  that  only  races  long  exposed 
to  a  disease  are  resistant  to  it,  so  that  whole  races  tend  to  die  out 
when  exposed  to  new  diseases  under  stringent  conditions — for 
example,  the  inhabitants  of  all  the  Western  world  when  exposed 
to  tuberculosis  ?  The  mutation  theory  is  not  complete  as  it  stands. 
The  fact  that  races  do  not  evolve  against  diseases  to  which  they 
are  not  exposed  demands  the  corollary  that  every  useless  mutation 
(e.g.  capacity  to  resist  measles)  is  also  so  harmful  that  nature 
eliminates  the  individual  possessing  it.  Otherwise  it  is  impossible 
to  account  for  the  fact — which  we  shall  be  in  a  position  to  perceive 
more  clearly  later — that  races  evolve  only  in  useful  directions.1 

327.  "  It  was  said  even  at  the  time  of  Drelincourt  that  no 
less  than  two  hundred  and  sixty-two  groundless  theories  of  sex 
had  been  suggested  ;  and  it  may  be  added  that  since  that  time 
there  has  been  no  falling  off  of  interest  in  the  sex  question  if  the 
number  of  new  theories  proposed  is  a  criterion."  The  latest  theory, 
that  which  I  venture  to  formulate,  is  sure,  therefore,  to  meet 
with  scepticism.  Nevertheless,  the  evidence  supporting  it  when 
gathered  together  appears  strong.  Whether  I  am  right  or  wrong, 
the  correct  interpretation  in  this  case,  as  in  other  instances, 
probably  lies  obvious  on  the  surface,  provided  we  do  not  allow 
1  See  chapter  xiii.  and  especially  §  435. 


200  THE  FUNCTION  OF  SEX 

ourselves  to  be  blinded  by  that  veil  of  familiarity  which  is  so  apt 
to  obscure  the  significance  of  common  facts.  To  me  it  seems 
likely  that  the  failure  to  discover  the  function  of  sex  is  due 
largely  to  the  circumstance  that  the  attention  of  biologists  has 
been  concentrated,  on  the  one  hand,  on  progressive  evolution,  and 
on  the  other  hand,  on  striking  abnormalities.  Retrogressive 
evolution,  which  is  every  wit  as  important,  every  wit  as  adaptive 
as  progressive  evolution,  has  received  scant  attention  ;  and 
biologists,  with  hardly  a  recent  exception,  have  attributed  it  to 
the  same  agency  (direct  selection)  as  produces  progression.  The 
fact  that  it  occurs  in  the  total  absence  of  direct  selection  has  not 
received  due  weight.  Presumably,  sex  has  some  function.  The 
two  theories  most  in  favour  with  biologists  at  preseut  are,  on  the  one 
hand,  the  hypothesis  that  it  renders  species  variable  and  so 
provides  materials  for  Natural  Selection,  and  on  the  other,  that  it 
mixes  parental  qualities  as  marbles  are  mixed.  We  have  already 
dealt  with  the  Mendelian  hypothesis.  No  one  not  a  Mendelian 
doubts  the  swamping  effect  of  sex  on  progressive  variations.  The 
function  of  sex,  therefore,  cannot  be  the  provision  of  progressive 
variations  as  materials  for  the  work  of  Natural  Selection.  Sex  itself 
must  have  been  evolved  by  the  prolonged  selection  of  pre-existing 
progressive  variations.1  Moreover,  it  has  been  proved  that  par- 
thenogenetic  species  display  such  variations  in  plenty.  Indeed,  a 
principal  part  of  the  work  of  Natural  Selection  seems  to  be  to 
confine  variations  within  useful  bounds. 

328.  Before  we  can  be  in  position  to  understand  the  effect  and 
the  function  of  conjugation,  we  must  study  normal  intra-varietal 
breeding.  We  are  quite  incapable  of  observing  its  effects  in  plants 
and  lower  animals.  Even  in  human  beings,  with  which  we  are  so 
familiar,  our  task  is  rendered  very  difficult  by  the  constant  presence 
of  spontaneous  variations  arising  independently  of  sex.  Modi- 
fications, due  to  the  action  of  the  environment  on  the  germ-cell 
as  well  as  on  the  soma,  also  complicate  matters.  However,  we 
have  no  reason  to  suppose  that  amongst  human  beings, 
members  of  a  natural  '  wild '  species,  the  effects  of  conjugation 
differ  greatly,  if  at  all,  when  the  breeding  is  inter-racial  from  what 
it  is  when  it  is  intra-racial.  Many  human  varieties  differ  so  widely 
that  when  they  cross  we  are  easily  able  to  note  the  effect  of  con- 

1  Possibly  it  originated  in  attempted  cannibalism  amongst  unicellular  organ- 
isms, an  attempt  which  resulted  in  beneficial  fusion.  Thence,  perhaps,  during  the 
evolution  which  adapted  species  for  conjugation,  arose  gradually  those  multi- 
tudinous sexual  differentiations  which  we  find  in  multicellular  animals  and  plants. 


STABILITY  OF  PARTHENOGENETIC  TYPES       201 

jugation.  In  every  instance  the  result  is  a  blend  which  persists 
in  subsequent  generations,  not  a  Mendelian  mixture.  Here, 
very  clearly,  the  effect  of  blending  is  retrogression  towards  the 
parental  and  varietal  mean.  If  many  races  interbred  it  would 
imply  retrogression,  within  the  limits  of  their  differences,  towards 
the  specific  mean,  consequently  towards  the  ancestral  type.  Thus, 
if  races  which  have  undergone  evolution  against  different  diseases 
cross,  the  resisting  powers  of  those  races  which  have  undergone 
progression  are  diminished  in  the  descendants.1 

329.  We  have  used  the  term  blending  as  including  all  degrees 
of  prepotency  up  to  the  exclusive  inheritance  of  the  character  of 
the  one  parent  and  the  permanent  loss  of  that  of  the  other.     Old 
established  characters  tend  always  to   be  prepotent  over   newer 
characters,  as  is  proved  by  the  fact  that  when  parents  differ  the 
progressive  variations  of  one  generation  tend  not  to  be  reproduced 
by  the  next.     It  is  also  proved  by  another  set  of  facts,  namely, 
that  retrogression  of  even  old-established  parts  is  a  constant  ac- 
companiment of  cessation  of  selection.      We  have  no  reason  to 
doubt  that,  apart  from  the  effects  of  blending,  offspring  tend  to 
vary  from  their  parents  retrogressively  as  well  as  progressively. 
Evidently  these  retrogressions  which  imply  reversions  to  an  old 
type,  tend  to  be  prepotent  over  the  type  which  has  become  the 
normal  of  the  race  ;  hence,  in  part  at  least,  retrogression  in  the 
absence  of  selection. 

330.  The  little    evidence  we  possess   concerning    parthenoge- 
netic  species  points  in  the  same  direction.     Their  useless  characters 
(e.g.    receptacula    seminis   in    Cypris  reptans)   are   very  persistent. 
Parthenogenetic   types   are   exceptionally  prolific   of  progressive 
varieties,  a  fact  which  clearly  indicates  comparative  lack  of  regres- 
sion and,  therefore,  of  retrogression. 

331.  The  fact  that  under  conditions  of  parthenogenesis  (complete 
or  partial)  "  thousands  of  forms  may  be  cultivated   side  by  side 
.  .  .  and  exhibit  slight  but  undoubted  differentiating  features,  and 
reproduce  themselves  truly  by  seed  "  2  is  very  significant.    It  affords 
evidence  (i)  that  progressive   variations   are   then  plentiful,  and 
therefore  that  bi-parental  reproduction  is  not  the  cause  of  them  ; 
(2)  that  such  variations  are  then  especially  persistent,  and  therefore 
that  conjugation  tends  to  plane  them  away,  and  (3)  that  fluctuations 
are  unstable,  not  because  they  are  due  to  "  varying  conditions  of 
food  supply,  temperature,  density,  moisture,  light,"  etc.,  but  because 
they  blend  with  one  another  in  bi-parental  reproduction.    Otherwise, 

1  See  §  464.  a  See  §  244  (footnote). 


202  THE  FUNCTION  OF  SEX 

since  persistent  variations  are  so  many  in  parthenogenesis,  we  must 
suppose  that  mutations  are  a  thousandfold  more  numerous  under 
that  condition  than  when  reproduction  is  bi-parental,  which  is,  to 
say  the  least,  unlikely. 

332.  Speaking   generally,  among   animals   that  reproduce  bi- 
parentally,  varieties  are  few  when  the  powers  of  locomotion  are 
great — that   is   when    mating  between   individuals   derived    from 
widely  separated  districts  is  common.     Thus,  avian  species  have 
few  varieties  except  when  spread  over  a  very  wide  area  or  an  area 
that  is  interrupted  by  natural  barriers,  and  often,  unlike  partheno- 
genetic   types,    only   a   single    variety   inhabits    a   whole  region. 
When  there  are  effective  barriers,  varietal  differentiation  is  usually 
noticeable.     When  the  powers  of  locomotion  are  less,  the  number 
of  varieties   is  greater.      Thus,  as  Gulick  noted,  every  valley  in 
Samoa   has   its    local    species   of    land-shells,   the   differentiation 
between  the  varieties,  species}  and  genera  being  proportionate  to 
the  distances  which  separate  them.1     All  this  indicates  strongly 
that  the  effect  of  sex  is  to  blend  characters.     If  the  theory  of  unit 
segregation  and  gametic  purity  were  true,  and,  as  a  consequence, 
that  of  blended  inheritance  untrue,  species  which  reproduce  sexually 
should  possess  at  least  as  many  varieties  as  those  the  reproduction 
of  which  is  parthenogenetic,  and  those  which  range  widely  as  many 
as  those  with  poorer  powers  of  locomotion.      In  that  case  there 
would  be,  not  only  no  approach  to  uniformity  through  conjugation, 
but  such   a  shuffling   of  characters  that  almost  every  individual 
would  form  a  variety  by  itself. 

333.  The  fact  that,  apart  from  the  sexual  traits,  all  the  individuals 
of  the  same  variety  differ,  with  rare  exceptions,  only  to  the  extent 
of  fluctuations,  is  presumptive  evidence  that  the  function  of  sex  is 
to  blend  parental  characters.     In  that  case  the  average  experience 
of  the  whole  race,  rather  than  the,  perhaps,  exceptional  experience  of 
single  individuals,  becomes  the  determining  factor  in  evolution.     The 
advantage  of  this  is  obvious);  for  most  individuals  are  more  likely 
to  have  an  average  than  an  exceptional  experience.     Moreover,  as 
I  say,  blending  when  combined  with  Natural  Selection  is  a  selecting 
agency.     Selection  eliminates  harmful  progressive  and  retrogressive 
variations,  and,  on  rare  occasions,  old-established  characters  that 
have  become  harmful.      Blending,  with  its  swamping  effects,  its 
general  tendency  to  produce  retrogression,  eliminates  useless  char- 
acters and  variations — characters  and  variations  which  are  merely 
useless  to  the  individual,  but  which,  if  accumulated,  would  become 

1  See  Darwinism,  by  Alfred  Russel  Wallace,  p.  43. 


THE  SPEED  OF  RETROGRESSION  203 

harmful  to  the  race.  Selection  may  be  compared  to  a  sculptor 
who  designs  and  rough  hews  a  statue ;  sex  to  a  colleague,  more 
skilful  mechanically,  who  chisels  out  the  finer  lines. 

334.  We  never  see  racial  progression  except  when  selection, 
natural   or   artificial,    is   at   work.     The   evidence   is,   that   given 
sufficient   time,   retrogression    invariably   occurs    when    there    is 
cessation  of  selection,  its  speed  being  proportionate  to  the  recency 
of  the  antecedent  progression.     Now,  when  a  character  (e.g.  limb) 
has  been  long  established,  constant  interbreeding  has  so  blended 
together  all  the  strains  of  a  race,  that  mating  individuals  differ 
comparatively  little.     At  any  rate,  apart  from  mutations,  which 
are  comparatively  rare   and  tend    to  be  eliminated,   individuals, 
exhibiting   every  gradation   between  the  extremes   of  '  normal ' 
variations,  occur — the  most  numerous  type  and  therefore  the  most 
influential  as  regards  inheritance  being  those  which  approximate 
most  closely  to  the  specific  mean.     In  such  cases,  therefore,  the 
retrogression  which   follows   the   cessation   of  selection   depends 
wholly  on  the  prepotency  of  new  retrogressive  variations,  and  is 
a  very  gradual  process.     But  when  the  character  (e.g.  any  of  the 
special  points  of  prize  breeds)  has  been  newly  established,  mating 
individuals    differ   more,   for   the   blending   will   have  been    less 
thorough,  and  retrogression,  therefore,  is  more  rapid.    It  is  possible, 
indeed   I  think  it  is   probable,  that   retrogression   follows   mere 
cessation  of  selection  even  in  parthenogenetic  species.     But  the 
prolonged  persistence  of  useless  structures  in  such  rapidly  repro- 
ducing types  as  Cypris  reptans,  as  well  as  the  fact  that  partheno- 
genetic  species   tend    to  break  into  a  multitude   of  progressive 
'  varieties,'  indicates  that  retrogression  on  cessation  of  selection 
is  a  slower  process  than  when  blending  is  present. 

335.  The  higher  animals  are  the  most  complex  products  of 
evolution.     The  multitude  and  differentiation  of  their  structures  is 
very  great,  and  the  fact  that  they  are  active  moving  machines  renders 
necessary  a  very  delicate  co-adaptation  of  all  their  parts.     A  tree 
may  differ,  always  does  differ,  greatly  in  shape  from  other  members 
of  the  species  ;  but,  if  a  higher  animal  diverges  much  from  his  type 
in  shape,  he  is  a  monster  and  cannot  persist      But  this  very  com- 
plexity of  structure  and  closeness  of  adjustment  increases  the  area 
of  variability  and  the  chance  that  variations  will  throw  the  whole 
machine  out  of  gear.     It  is  significant  that  the  reproduction  of  all 
these  animals  is  bi-parental.     The  blending  of  useful  characters, 
combined  with  the  automatic  planing  away  of  redundancies,  relieves 
Natural  Selection  of  half  its  task  of  adapting  them  to  the  environ- 


204  THE  FUNCTION  OF  SEX 

ment.  When  considering  Natural  Selection,  we  are  apt  to  think 
of  the  progressive  variations  of  the  individual  as  passing  unchanged 
to  his  descendants.  As  a  fact,  apart  from  his  variations,  the 
descendant  is,  so  to  speak,  a  composite  photograph  of  ancestors 
from  which  useless  characters  are,  more  or  less,  excluded.  It  is 
largely  because  conjugation  has  planed  away  redundancies  and 
blended  into  a  congruous  whole  much  that  enabled  the  survivors  in 
past  generations  to  persist  till  they  had  offspring  that  the  individual 
is  so  closely  adapted  to  the  average  environment  of  his  race. 

336.  Self-fertilization  is  not  uncommon  in  plants,  and  it  occurs 
also  amongst  vegetative  marine  animals.     Doubtless  it  has  arisen 
as   a   substitute    for   cross-fertilization,    owing    to    the   uncertain 
occurrence  of  the  latter  amongst  the  individuals  of  stationary  and 
scattered  types.     The  germ-cells  of  an  individual  differ  amongst 
themselves,  but  not,  on  the  average,  to  the  same  extent  as  germ- 
cells    derived    from    different    individuals.      In    self-fertilization, 
therefore,  the  influence  of  conjugation,  though  still  potent,  is  less 
than  in   cross-fertilization.     Presumably,   however,  it  is  sufficient 
for  the   needs  of  the  comparatively  simple  types  among  which 
it  is  found.     Parthenogenesis  is   comparatively  rare,  and  occurs 
as  a  rule  among  simple  forms,  the  multiplication  of  which  is  very 
rapid,  and  which  thus  provide  very  abundant  materials  for  Natural 
Selection.     The  theory  that  the  function  of  sex  is  to  bring  about 
the  retrogression  of  useless  characters  by  the  blending  of  paren- 
tal  traits,    therefore,    accords   well,  not   only   with    the   facts   of 
bi-parental  reproduction,  but  also  with  those  of  self-fertilization 
and  parthenogenesis. 

337.  The  problem  of  sex  occupies  at  present  a  disproportionate 
share  of  biological  attention.     The  study  of  it,  under  the  name  of 
Mendelism,  is   very  fashionable.     Nevertheless,    from   a  practical 
point  of  view,  indeed  from  every  point  of  view,  it  is  of  lesser  im- 
portance than  many  other  biological  problems.     A  complex  and 
difficult  question,  it  cannot  be  solved  except  by  examining  it  from 
all  points  of  view,  by  utilizing  all  the  evidence  available,  and  testing 
our  thinking   carefully.     It  cannot   be  too   often  or   too  forcibly 
reiterated  that  the  only  extensive  body  of  evidence  in  our  possession 
relating  to  normal  intra-varietal  breeding  and  the  crossing  of  natural 
varieties  is  that  drawn  from  human  races.    That  evidence  indicates 
decisively  that  offspring  blend  parental  characters.     To  restrict  our 
data  to  the  scanty  and  imperfect  material  obtainable  by  crossing 
domestic  varieties  for  a  few  generations,  and  even  then  by  observ- 
ing only  the  inheritance  of  glaring  parental  differences,  is  to  court 


SCIENTIFIC  METHOD  205 

failure.  It  would  be  as  reasonable  to  isolate  a  party  of  English 
people,  rear  them  for  three  or  four  generations  under  conditions  as 
foreign  as  they  could  possibly  be  made,  and  then,  while  excluding 
all  other  evidence  as  non-experimental  and  therefore  fit  only  for 
essayists,  attempt  from  the  data  thus  obtained  to  write  an  account 
of  the  mode  of  development  of  English  society.  I  think  a 
historian  who  adopted  such  a  method  would  not  be  deemed  wise, 
even  if  he  were  deemed  a  historian  ;  but  the  illustration  does  not 
greatly  exaggerate  the  method  and  claims  of  some  experimental 
workers  who  esteem  themselves  austerely  scientific.  "  Experiments 
on  crossing  can  give  nothing  but  laws  of  crossing;  it  may  be 
possible  that  some  of  these  laws  may  be  applicable  to  the  breeding 
of  pure  races,  but  this  cannot  be  decided  without  definite  trial."  1 
A  full  appreciation  of  the  importance  of  experimental  work  need 
not  blind  us  to  the  value  of  evidence  differently  obtained,  nor  to 
the  fact  that  there  are  problems  of  heredity  other  than  the  effect 
of  conjugation.  In  truth,  heredity  is  a  subject  much  wider,  much 
more  important  practically,  much  more  fascinating  intellectually 
than  is  implied  in  a  good  deal  of  recent  work. 

1  Mr  Udney  Yule. 


CHAPTER  X 
SUMMARY 

Adaptation — Stimuli  to  growth — The  confusion  as  to  what  is  innate  and 
what  is  acquired — Variations — Spontaneous  variability  and  insusceptibility  of 
the  germ-plasm — Recapitulation — The  function  of  conjugation — Blending — 
Alternative  recapitulation — Fluctuations  and  mutations — The  difficulties  pre- 
sented by  the  different  sciences — Methods  of  inquiry — The  method  of  comparing 
races — Materials  supplied  by  human  beings — The  greater  problems  of  Heredity. 

338.  "lt~lf  7"E  see  then  that  the  great  outstanding  feature  of  living 
beings  is  that,  in  part  and  whole,  they  are  adapta- 
tions. For  example,  in  man,  the  being  we  know 
best,  very  few  characters  exist  the  utility  of  which  in  past  or  present 
has  not  already  been  ascertained.  Doubtless  a  proportion  of  his 
characters — for  instance  susceptibility  to  the  charm  of  alcohol — 
may  be  mere  by-products  of  evolution,  accidental  accompaniments 
of  useful  characters ;  but,  speaking  comparatively,  they  are  rare. 
His  nervous,  circulatory,  muscular,  glandular,  digestive,  and  other 
systems,  the  mass  of  his  characters,  his  specific  and  varietal 
traits  as  distinguished  from  his  personal  variations,  are  nearly 
all  demonstrably  useful.  We  shall  see  that  what  is  true  of  his  body 
is  true  also  of  his  mind.  The  variations  of  the  individual  are,  of 
course,  not  all  useful,  but  the  spontaneous  variability  to  which  they 
are  due  and  which  supplies  the  materials  for  selection  is  an 
immensely  useful  trait  which  has  been  evolved  through  Natural 
Selection  into  an  adaptation.  Presumably  adaptation  is  not  less 
perfect  in  plants  and  lower  animals  than  in  man.  Apparently  they 
have  been  just  as  much  subjected  to  selection.  In  all  probability, 
therefore,  if  we  are  less  able  to  trace  the  utility  of  all  their 
characters,  it  is  only  because  here  our  knowledge  is  less  complete. 
It  must  be  borne  in  mind,  however,  that  nature  can  do  no  more 
than  choose  from  the  variations  or  combinations  of  variations  that 
happen  to  be  presented  to  her  for  selection.  If,  therefore,  two 
sections  of  a  species  separated,  but  continued  to  exist  under 
conditions  which  (were  it  possible)  were  identical,  they  would  still 
be  sure  to  differentiate ;  for  neither  the  variations  presented  to 
nature  for  selection  nor  the  accidents  of  survival  would  be  quite 

206 


THE  STIMULI  TO  DEVELOPMENT  207 

the  same.  If,  then,  two  varieties  (e.g.  of  man)  arise  in  different 
localities,  it  does  not  follow  necessarily  that  in  each  locality  they 
have  diverged  progressively  in  the  most  useful  direction  conceivable, 
but  only  that  each  has  diverged  in  a  useful  direction. 

339.  Except  actual   injuries,    as   distinguished  from   vital   re- 
actions to  injury,  all  the  characters  of  living  beings  result  from  an 
interaction  between  the  hereditary  tendencies  or  potentialities  of 
the  individual  and   stimuli  which  awaken   them   to  activity.     In 
essence,  all  evolution  consists  in  the  evolution  of  these  hereditary 
tendencies — that  is,  in  the  evolution  of  the  germ-plasm. 

340.  There  are  many  such  stimuli  to  development.     Amongst 
the   principal  are  nutriment,  use,  and  injury.     In  order  to  avoid 
unnecessary  complications   in  the  argument,  I  have   ignored  all 
stimuli  save  the  three  named,  or  rather  I  have  roughly  grouped 
under   the   head    of  nutriment   all  stimuli  save   use   and  injury. 
Here  I  have  merely  followed  established  biological  custom,  which 
distinguishes  characters  as  inborn  and  acquired,  and  separates  the 
latter  into  those  resulting,  on  the  one  hand,  from  use,  and  on  the 
other,  from  injury.     Nutriment  supplies,  not  only  a   stimulus  to 
development,  but  the  materials  for  all  growth.     All  the  '  normal ' 
structures  of  many  species  appear  to   develop   wholly  under  the 
influence  of  this  stimulus,  and  many  of  the  structures  of  all  species 
so  develop.     In   every   case   the   beginnings   of   all   growth   are 
attributable  to  it,  for,  of  necessity,  it  is  the  first  stimulus  to  which 
each  organism  and  structure  responds.     The  capacity  to  develop 
under  the  influence  of  use  or  injury  is  present  only  in  structures 
where  it  is  useful,  at  a  time  when    it  is  useful,  and  only   to  an 
extent  which  is  useful.     The  power  of  responding  by  growth  to 
injury  (regeneration,  healing)  has  been  closely  studied  by  biolo- 
gists.    That  of  responding  to  the  stimulus  of  use  has  been  more 
neglected.     The   utmost   confusion    prevails,  for   example,  as   to 
which  characters  in  each  species  develop  under  the  influence  of 
nutrition,  and  which  (if  any)  under  that  of  use.     When,  however, 
we  study  mind  we  shall  see  that  this  question  is  the  most  interest- 
ing and  practically   important   of  all  the   problems   of  biology. 
Probably  the  great   Lamarckian  controversy,  which  still  lingers, 
would  have  ended  as  soon  as  it  began,  if  biologists  had  carefully 
defined  their  terms  and  noted  in  what  species,  in  what  characters, 
and  to  what  extent  the  power  of  responding  to  the  stimulus  of 
use  was  developed  :  in  other  words,  if  they  had  studied  this  power 
as  what  it  really  is,  an  adaptation,  a  product  of  evolution,  not   a 
chance  or  necessary  property  of  living  protoplasm. 


208  SUMMARY 

341.  Modern  biologists  are  accustomed  to  divide  the  characters 
of  multicellular   living   beings   into   those   which    are   inborn   or 
innate  and  those  which  are  acquired,  and  to  declare  that  only  the 
former  can  be  inherited  by  offspring.     They  are  mistaken.     No 
character,  in  any  real  sense,  is  more  innate  than  any  other.     The 
child  inherits  nothing  from  his  parents.    These  terms  are  convenient, 
inasmuch  as  they  enable  us  to  avoid  circumlocution,  but  they  are 
inaccurate.     The  true  distinction  between  characters  results  from 
the  stimuli  under  which  they  arise.     The  so-called  acquirements 
arise  under  the  stimulus  of  use  or  injury ;    the  so-called  inborn 
characters  under  other  stimuli,  especially  that  of  nutriment.     The 
true  meaning  of  the  statement,  that  acquirements  are  not  trans- 
missible, is  that  the  characters  which  arise  under  the  stimulus  of 
use  or  injury  in  the  parent  are  not  reproduced  in  the  child  under 
the  stimulus  of  nutriment.     This  sudden  transference  of  characters 
from  one  category  in  the  parent  to  another  in  the  child  certainly 
never  occurs.     In  the  first  category  they  are  products  of  evolution  ; 
if  they  were  reproduced  in  the  second  they  would  be  products  of 
miracle. 

342.  Offspring  resemble  their  parents,  but  with  minor  differ- 
ences.    These  differences  are  due  either  to  differences  in  the  play 
of  stimuli  on  individuals,  or  to  germinal  differences.     The  latter 
are  termed   variations,   and    on   them    all   evolution    is    founded. 
Massive  evidence  indicates  that  immensely  the  greater  number  of 
variations    are   spontaneous.       This,   in     turn,   implies    that   the 
germ-plasm   is   highly   insusceptible  to  the  direct   action  of  the 
environment.     A  close    examination  of  the   evidence   renders   it 
clear  that  living  beings  could  not  have  persisted  on  earth  unless 
their   variations   had    been    spontaneous    and   their    germ-plasm 
resistant. 

343.  Variations  are  either  progressive  or  retrogressive.     Since 
the  general  resemblance  between  parents  and  offspring  is  due  to 
the  fact  that  the  latter  in  their  own  development  closely  recapitu- 
late the  development  of  the  former,  a  progressive  variation  implies 
a  prolongation  of  the  parental  development,  a  complete  recapitu- 
lation with  an  additional  step.     On  the  other  hand  a  retrogressive 
variation   implies  an  incomplete   recapitulation,   an    abbreviation. 
Since  offspring  recapitulate  (with  variations)  the  parental  develop- 
ment,  they  necessarily  recapitulate  (with  interpolated  additions 
and  subtractions  due  to  innumerable  interpolated  progressive  and 
retrogressive  variations  that  occurred  in  the  ancestry)  the  evolution 
of  the  species.     It  follows  that  retrogression  implies  a  reversion  to 


DIRECT  AND  INDIRECT  SELECTION  209 

the  ancestral  type.  It  further  follows  that  (as  regards  each  char- 
acter) ancestors  are  represented  by  the  individual,  not  en  masse, 
but  in  orderly  succession.  The  so-called  contributions  of  ancestors 
are  nothing  other  than  reversions,  that  is  to  say,  failures  to 
recapitulate  the  life-history  beyond  the  points  reached  by  the 
ancestors,  or  else  the  reappearance  of  hitherto  dormant  characters. 
The  truth  of  recapitulation,  though  admitted  by  the  majority  of 
biologists,  is  universally  ignored  when  theories  of  heredity  are 
formulated.  Biologists  found  their  belief  in  recapitulation  solely 
on  very  uncertain  and  fragmentary  embryological  evidence.  They 
have  not  realized  that,  given  facts  which  are  admitted  to  be  true, 
any  method  of  development  other  than  by  a  recapitulation  of  the 
life-history  is  unthinkable.  This  failure,  together  with  the  failure 
to  distinguish  the  true  nature  of,  the  true  distinction  between, 
innate  and  acquired  characters,  has  been  in  the  past  a  principal 
obstacle  to  a  scientific  systematization  of  the  facts  of  heredity,  a 
main  source  of  error,  confusion,  wild  speculation,  and  endless 
controversy. 

344.  Evolution  (i.e.  adaptation)   depends  as   much  on   retro- 
gression as  on  progression.     Direct  Natural  Selection  is  concerned 
almost  exclusively  with  progression.     Only  seldom  is  it  a  cause  of 
retrogression,  which,  with  rare  exceptions,  occurs  only  on  cessation 
of  selection,  and  is  due  to  the  general  tendency  to  reversion — i.e. 
the  general  tendency  to  abbreviate  rather  than  to  prolong  the  life- 
history.     In  the  last  analysis,  however,  this  tendency  is  itself  due 
to  the  Natural  Selection  of  strains  that  possess  it  in  the  right 
degree.     Retrogression  planes  away  all  redundancies,  all  useless 
variations  and  structures  that  have  lost  their  utility. 

345.  The  function   of  conjugation  is  to  blend  parental  char- 
acters.    The  average  experience  of  the  race  is  thus  substituted 
for  the  special  experience  of  the  individual.      Moreover,  in  each 
blend  retrogressive  (i.e.  the  more  ancient)  characters  tend  to  be 
prepotent   over   progressive   (i.e.    less   ancient)    characters.      The 
effect  of  this  blending,  therefore,  is  to  bring  about  the  more  or  less 
rapid  retrogression  of  useless  characters — a  retrogression  which  is 
only  checked  or  reversed  by  selection.     Sex,  therefore,  is  as  much 
a  selecting  agency  as  Natural  Selection.     Since  every  gradation 
occurs   between  equal   blending   of  parental   characters   and  the 
exclusive  inheritance  of  the  character  of  one  parent  only,  it  is 
convenient  to  class  even  exclusive  inheritance  under  the  head  of 
blended    inheritance.      There   is    no   such    thing    as    alternative 
inheritance  ;  there  is  only  alternative  patency  and  latency.     When 

14 


210  SUMMARY 

this  occurs  the  child  inherits  the  characters  of  both  parents  but 
develops  those  of  only  one.  Blending  then  occurs  between  the 
patent  traits  of  one  parent  and  the  latent  traits  of  the  other. 
Therefore,  speaking  practically,1  all  inheritance  is  blended  in  bi- 
parental  reproduction.  Unit  segregation,  gametic  purity,  and 
independent  inheritance  of  characters  (in  the  Mendelian  sense)  are 
all  myths  that  have  been  founded  on  experiment  but  have  not 
been  tested  by  it  or  in  any  other  way.  They  are  mere  guesses. 
The  evidence  from  which  they  have  been  inferred  is  very  restricted 
and  fragmentary,  and,  especially  when  considered  in  connection 
with  other  larger  bodies  of  fact,  really  points  to  quite  other 
conclusions. 

346.  In  sexually  dimorphic  species  every  individual  possesses 
one  set  of  non-sexual  characters,  all  of  which  are  patent,  and  two 
sets  of  sexual  characters  of  which  only  one  set  is  patent.     But 
if  parents  differ  greatly  in  any  non-sexual  character,  the  reproduc- 
tion of  it  tends  to  follow  the  sexual  mode.     This  rarely  happens 
in  the  normal  intra-varietal  breeding  of  natural  varieties,  for  under 
such   conditions   individuals   who  differ   greatly   from   the   norm 
seldom  survive   and  have   offspring,  but   it   is   quite   a  common 
occurrence  under  artificial  selection,  which  is  distinguished  from 
natural  selection  by  the  choosing   of  mutations   rather   than  of 
fluctuations,  the  crowding  together  of  newly  formed  varieties  in 
the  same  locality,  and  their  constant  intercrossing  through  design 
or  accident.     All  the  evidence  indicates  that  in  nature  varieties 
arise  solely  or  almost   solely    under   conditions    of  geographical 
separation.      Artificial    Selection    and    artificial    varieties    there- 
fore   differ    profoundly    from     Natural     Selection    and    natural 
varieties.     In  artificial  varieties  are  found  dormant  traits  which 
are  practically  unknown  in  natural  varieties.     Judging  from  the 
analogy  of  patent  characters,  it  is  an  error  to  suppose  that  dormant 
traits  persist  for  ever.     Having  no  utility,  they  are  not  maintained 
by  Natural  Selection,  and  therefore  tend  to  disappear   in   time. 
Thus  when  the  horse  is  crossed  with  the  Burchell  zebra  the  repro- 
duction  of  the  long  dormant  ancestral  stripes    is  very  faint  as 
compared  to  the  vivid  reproductions  of  ancestral  coloration  which 
may  appear  in  offspring  when  two  dull-plumaged  breeds  of  poultry 
or  two  white  varieties  of  garden  flowers  are  crossed. 

347.  The  progress  of  science  depends  first  on  the  collection  of 
verified  facts,  and  second  on  their  systematic  arrangement.      The 
facts  must  be  verifiable  or  we  cannot  know  them  to  be  true.     They 

1  See  §  322. 


THE  DATA  OF  THE  SCIENCES  211 

must  be  systematized,  or  they  are  of  no  greater  scientific  value 
than  the  amorphous  mass  of  data  with  which  casual  experience 
stores  our  minds.  The  methods  by  which  facts  are  collected  and 
arranged  differ  according  to  circumstances. 

348.  In  some  sciences,  for  example  systematic  botany,  zoology, 
and  anatomy,  the  facts  are  nearly  all  patent  and,  once  ascertained, 
fall    so   naturally  and  easily  into   the   right    categories  that  the 
difficulty    of   systematization,    of    discovering    the   relationships 
between  the  facts,  is  reduced  to  a  minimum.     In  others,  the  ex- 
perimental sciences,  for  example  physics  and  chemistry,  very  few 
facts  are  patent  to  our  senses :  the  main  difficulty  lies  in  ascertain- 
ing them.     Therefore  special  methods  of  investigation  have  been 
devised.      In  yet  other  sciences,  for  example  heredity,   though 
many  facts  are  patent,  others  are  obscured,  and  the  relationships  of 
nearly  all  are  hard  to  ascertain.     Consequently  we  have  difficulties 
both  in  discovering  information  and  in  arranging  it.     The  patent 
facts  can  be  simply  observed.     The  obscured  facts  must  be  rendered 
patent  by  means  that  clear  away  the  obscuring  conditions.     The 
difficulties  in  arranging  the  facts  must  be  met  by  testing  our  think- 
ing with  especial  care.     In  this  way  only  is  it  possible  to  achieve 
an  approach  to  exactness. 

349.  Very  remarkable  notions  as  to  what  constitutes  science 
are  prevalent  amongst  sections  of  biologists.     Thus  medical  men, 
who  are  biologists  in  the  sense  that  they  are  students  of  a  living 
being,  frequently  denounce  deduction.     Apparently  they  are  un- 
aware that  the  correctness  of  inductive  thinking  can  be   tested 
efficiently  only  by  means  of  it,  and  that  mathematics,  the  purest 
and  most  accurate  of  sciences,  the  model  for  the  rest,  is  almost 
purely   deductive.      Again,    systematic   zoologists   and    botanists 
sometimes  denounce  'speculation.'      That   is   they   denounce  all 
thinking  which  is  not  very  easy,  all  attempts  to  ascertain  relations 
that  are  not  very  obvious.  Yet,  again,  some  experimental  observers, 
appealing  to  physics  and  chemistry,  sciences  that  are  both  accurate 
and  experimental,  often  insist  that  biology  must  be  made  accurate 
by  being  made  experimental.     But  physics  and  chemistry  are  not 
accurate   because   they  are    experimental,  but  because    the  data 
on   which   they  are  founded  are  capable  of  being   as   precisely 
measured    as   it   is  possible   to    measure   anything,   and   because 
the   students   of  them  test  their  thinking  with  great  care.       In 
biology,  we  must,  of  course,  when  necessary,  use  experiment  as 
well  as  every  other  means  of  ascertaining  truth.     But  that  is  one 
thing.     Quite  a  different  thing  is  what  has  actually  happened  in 


212  SUMMARY 

practice — the  limitation  of  thought  to  data  provided  by  experi- 
ment, and  the  abandonment,  from  lack  of  material,  of  all  attempts 
to  ascertain  the  correctness  of  hypotheses.  The  experimental 
method  can  do  no  more  than  fill  some  lacunae  in  our  already  wide 
knowledge  of  living  beings.  In  the  past  men  have  sometimes 
filled  these  gaps  with  imaginary  facts  and  have  speculated  wildly. 
But  such  lapses  from  scientific  caution  afford  no  excuse  for  treat- 
ing the  gaps  when  filled  by  experiment  with  authentic  facts  as  the 
whole  of  knowledge  and  then  speculating  still  more  wildly. 

350.  Splendid   examples   of    scientific   method,   of  combined 
induction   and  deduction,  are   the  hypotheses   of  evolution  and 
Natural  Selection.     The  actuality  of  evolution  was  suspected  even 
by  the  Greeks,  but  modern  conviction,  founded  as  it  is  on  authenti- 
cated facts  and  carefully  tested  thinking,  is  more  surely  based. 
By  linking  together  particular  facts  we  infer  (i)  that  it  is  possible 
to  create  new  varieties  of  animals  and  plants  by  careful  artificial 
selection,  (2)  that  varieties,   species,  orders,  and  genera  tend  to 
shade  into  one  another,  (3)  that  species  inhabiting  the  same  or  adja- 
cent areas  tend  to  have  features  more  alike  than  those  more  widely 
separated,  (4)  that  the  remains  of  animals  and  plants  preserved 
in   geological   strata   indicate  that    related   species,    which   were 
widely  separated  in  time,  were  as  a  rule  more  unlike  than  those 
that  were  more  nearly  contemporary,  and  (5)  that  the  structures  of 
embryos  are  often  more  suggestive  of  lower  types  than  of  their 
own  adult  progenitors.     Linking  together  all  these  inductions,  as 
in  reaching  them  we  linked  together  particular  facts,  we  are  able 
to  infer  the  hypothesis  of  evolution.     In  this  way,  not  only  is  a 
deeper  knowledge  and  a  larger  synthesis  achieved,  but   we   are 
able  to  perceive  a  new  and  very  valuable  aspect  of  truth  which 
induction  could  never  have  established  unaided  by  deduction,  and 
which  suggests  many  fresh  inductions  and  deductions  which,  again, 
not  only  reveal  still  newer  truths,  but  tend  to  test  the  aspect  of 
reality,  which  was  reached  in  part  by  deduction. 

351.  Darwin  accepted  the  theory  of  evolution  and    linked   it 
with  the  inductions — which  had   previously   been    more   or   less 
familiar  to  all  men — (i)  that  offspring  tend  to  vary  from  their 
parents,   (2)  that  some  of  them   are   better  adapted   to   achieve 
survival  than  others,  (3)  that  they  tend  to  outnumber  their  parents, 
(4)   that,   nevertheless,    the   number   of  individuals   in    a  species 
does  not,  as  a  rule,  increase,  and  (5)  that  species  are  adaptational 
forms.     Noting  that  all  these  inductions  were  in  harmony   and 
testing  them  rigorously,  he  linked  them  together  in  the  hypothesis 


DARWIN'S  WORK  213 

of  Natural  Selection.  His  reasoning  was  largely  deductive,  for,  apart 
from  the  tests  to  which  he  subjected  his  thinking,  his  attention  was 
not  attracted  by  human  disease  and,  consequently, he  never  observed 
Natural  Selection  actually  at  work.  He  was  unable,  therefore,  to 
reach  his  wider  synthesis  through  an  actual  observation  of  parti- 
cular facts  or  test  it  by  an  appeal  to  them,  but  his  work  was  fertile 
in  suggestions — hence,  for  example,  Poulton's  attempt  to  demon- 
strate Natural  Selection  amongst  chrysalises,  and  Weldon's 
attempt  to  prove  its  occurrence  amongst  crabs.  Hence  also  many 
biometric  inquiries. 

352.  Starting  from  the  point  at  which  Darwin  stopped,  accept- 
ing his  theory  of  evolution  by  Natural  Selection,  and  combining 
with  it  the  hypotheses  which  we  reach  by  induction,  that  species 
tend  to  retrogress  on  cessation  of  selection,  and  that  offspring 
recapitulate  the  main  features  of  the  parental  development,  we  are 
able  to  infer  (i)  that  retrogressive  variations  tend  to  predominate 
over  progressive  variations,  (2)  that,  with  rare  exceptions,  variations 
are  spontaneous,  and  that  spontaneous  variations  tend  to  occur  all 
round  the  specific  mean,  (3)  that,  therefore,  the  germ-plasm  is 
highly  insusceptible  to  change  through  the  direct  action  of  the  en- 
vironment, (4)  that,  apart  from  his  own  progressive  variations,  the 
development  of  the  individual  is  an  abbreviated  and  inaccurate 
recapitulation  of  the  evolution  of  the  race,  and  (5)  that,  therefore, 
every  retrogressive  variation  is,  in  effect,  a  reversion.  Here  we 
formulate  laws  or  generalizations  of  heredity  which  are  probably 
as  nearly  fundamental  as  it  is  possible  to  reach  in  the  present  state 
of  our  knowledge.  As  in  the  case  of  Natural  Selection,  the  process 
of  reasoning,  since  we  endeavour  to  ascertain  whether  our  laws  are 
in  harmony  with  one  another  and  with  reality,  is  largely  deductive. 
But,  granting  the  premises  from  which  we  started,  and  none  of 
them  are  seriously  disputed,  I  believe  we  must  not  think  at  all,  or 
we  must  think  in  terms  of  miracle,  or  we  must  accept  the  laws  as 
true.  And,  very  obviously,  if  they  are  true,  if  they  are  real  laws, 
we  have  made  a  step  towards  rendering  biology  (or  at  least  the 
study  of  heredity  and  evolution)  a  deductive  science — towards 
establishing  it  on  the  basis  of  a  few  generalizations,  to  which  a  vast 
mass  of  data,  already  discovered  or  yet  to  be  discovered,  may  be 
linked  by  chains  of  causation,  that  is  to  say,  towards  attaining 
that  goal  which  is  the  aim  of  all  science.1 

1  "  It  will  be  seen  hereafter  that  there  are  weighty  scientific  reasons  for  giving 
to  every  science  as  much  of  the  character  of  a  Deductive  Science  as  possible  ; 
for  endeavouring  to  construct  the  science  from  the  fewest  and  the  simplest  possible 


214  SUMMARY 

353.  The  method  of  inquiry  on  which  Darwin  principally  relied, 
and  which  enabled  him  to  affect  so  great  a  revolution  in  modern 
thought,  was  to  compare  varieties  and  races  living  under  one  set 
of  conditions  with  those  living  under  another.  Having  noted  the 

inductions,  and 'to  make  these,  by  any  combinations,  however  complicated,  suffice 
for  proving  even  such  truths,  relating  to  complex  cases,  as  could  be  proved,  if 
we  chose,  by  inductions  from  specific  experience.  Every  branch  of  natural 
philosophy  was  originally  experimental ;  each  generalization  rested  on  a  special 
induction,  and  was  derived  from  its  own  distinct  set  of  observations  and  experi- 
ments. From  being  sciences  of  pure  experiment,  as  the  phrase  is,  or,  to  speak 
more  correctly,  sciences  in  which  the  reasonings  mostly  consist  of  no  more  than 
one  step,  and  are  expressed  by  single  syllogisms,  all  these  sciences  have  become 
to  some  extent,  and  some  of  them  in  nearly  the  whole  of  their  extent,  sciences  of 
pure  reasoning  ;  whereby  multitudes  of  truths,  already  known  by  induction  from 
as  many  different  sets  of  experiments,  have  come  to  be  exhibited  as  deductions 
or  corollaries  from  inductive  propositions  of  a  simpler  and  more  universal 
character.  Thus  mechanics,  hydrostatics,  optics,  acoustics,  thermology,  have 
successively  been  rendered  mathematical ;  and  astronomy  was  brought  by  Newton 
within  the  laws  of  general  mechanics.  Why  it  is  that  the  substitution  of  this 
circuitous  mode  of  proceeding  for  a  process  apparently  much  easier  and  more 
natural,  is  held,  and  justly,  to  be  the  greatest  triumph  of  the  investigation  of 
nature,  we  are  not,  in  this  stage  of  our  inquiry,  prepared  to  examine.  But  it  is 
necessary  to  remark,  that  although,  by  this  progressive  transformation,  all  sciences 
tend  to  become  more  and  more  Deductive,  they  are  not,  therefore,  the  less  Induc- 
tive ;  every  step  in  the  Deduction  is  still  an  Induction.  The  opposition  is  not 
between  the  terms  Deductive  and  Inductive,  but  between  Deductive  and  Experi- 
mental. A  science  is  experimental  in  proportion  as  every  new  case,  which  presents 
any  peculiar  features,  stands  in  need  of  a  new  set  of  observations  and  experiments 
— a  fresh  induction.  It  is  deductive  in  proportion  as  it  can  draw  conclusions, 
respecting  cases  of  a  new  kind,  by  processes  which  bring  those  cases  under  old 
inductions  "(J.  S.  Mill,  Logic,  Bk.  II.  chap.  iv.  §  5).  "  The  discoveries  which  change 
the  method  of  a  science  from  experimental  to  deductive  mostly  consist  in 
establishing,  either  by  deduction  or  by  direct  experiment,  that  the  varieties  of 
a  particular  phenomenon  uniformly  accompany  the  varieties  of  some  other 
phenomenon  better  known.  Thus  the  science  of  sound,  which  previously  stood 
in  the  lowest  rank  of  merely  experimental  science,  became  deductive  when  it 
was  proved  by  experiment  that  every  variety  of  sound  was  consequent  on,  and 
therefore  a  mark  of,  a  distinct  and  definable  variety  of  oscillatory  motion  among 
the  particles  of  the  transmitting  medium.  When  this  was  ascertained  it  followed 
that  every  relation  of  succession  or  co- existence  which  obtained  between 
phenomena  of  the  more  known  class,  obtained  also  between  the  phenomena  which 
correspond  to  them  in  the  other  class.  Every  sound  being  the  mark  of  a  particular 
oscillatory  motion,  became  a  mark  of  everything  which,  by  the  laws  of  dynamics, 
was  known  to  be  inferable  from  that  motion  ;  and  everything  which  by  those 
same  laws  was  a  mark  of  any  oscillatory  motion  among  the  particles  of  an  elastic 
medium,  became  a  mark  of  the  corresponding  sound.  And  thus  many  truths, 
not  before  suspected,  concerning  sound,  become  deducible  from  the  known  laws 
of  the  propagation  of  motion  through  an  elastic  medium  ;  while  facts  already 
empirically  known  respecting  sound  become  an  indication  of  corresponding 
properties  of  vibrating  bodies,  previously  undiscovered  "  (op.  cit.,  II.  iv.  7).  "  We 
have  thus  already  come  within  sight  of  a  conclusion  which  the  progress  of  the 
inquiry  will,  I  think,  bring  before  us  with  the  clearest  evidence,  namely,  that  in  the 


DARWIN'S  METHOD  215 

differences  between  races  and  between  conditions,  he  sought  to  ac- 
count for  the  former  by  the  latter.1  His  very  learning  and  the  skill 
with  which  he  used  it  contributed,  through  exhaustion  of  materials, 
to  render  the  task  of  his  successors  difficult.  The  actuality  of 
evolution  was  proved  and  the  method  of  evolution  demonstrated, 
but  many  problems  of  heredity  remained.  A  great  deal  of  splendid 
work  was  done  subsequently,  but  it  was  felt  that  our  knowledge  of 
wild  plants  and  animals  was  very  vague,  and  an  impression  spread 
that  laboratory  methods  alone  were  capable  of  supplying  information 
sufficiently  exact. 

354.  But,  clearly,  if  we  are  able  to  trace  precisely  the  changes 
a  race  undergoes  as  a  reaction  to  the  conditions  under  which  it 
dwells,  if  we  are  able  to  establish  clearly  the  connections  between 
causes  and  effects,  we  observe  nothing  less  than  an  actual,  a  very 
perfect  experiment.  Such  an  experiment,  since  it  is  conducted  by 

sciences  which  deal  with  phenomena  in  which  artificial  experiments  are  impossible 
(as  in  the  case  of  astronomy),  or  in  which  they  have  a  very  limited  range  (as  in 
mental  philosophy,  social  science,  and  even  in  physiology),  induction  from  direct 
experience  is  practised  at  a  disadvantage  in  most  cases  equivalent  to  impracti- 
cability ;  from  which  it  follows  that  the  methods  of  those  sciences,  in  order  to 
accomplish  anything  worthy  of  attainment,  must  be  to  a  great  extent,  if  not 
principally,  deductive.  This  is  already  known  to  be  the  case  with  the  first  of 
the  sciences  we  have  mentioned,  astronomy ;  that  it  is  not  generally  recognized 
as  true  of  the  others  is  probably  one  of  the  reasons  why  they  are  not  in  a  more 
advanced  state  "  (op.  ctt.,  III.  vii.  3). 

1  "  If  what  is  called  observation  is  at  so  great  a  disadvantage,  compared  with 
artificial  experimentation,  in  one  department  of  the  direct  exploration  of  pheno- 
mena, there  is  another  branch  hi  which  the  advantage  is  all  on  the  side  of  the 
former. 

"  Inductive  inquiry,  having  for  its  object  to  ascertain  what  causes  are  connected 
with  what  effects,  we  may  begin  this  search  at  either  end  of  the  road  which  leads 
from  one  point  to  the  other  ;  we  may  either  inquire  into  the  effects  of  a  given  cause 
or  into  the  causes  of  a  given  effect.  The  fact  that  light  blackens  chloride  of  silver 
might  have  been  discovered  either  by  experiments  on  light,  trying  what  effect 
it  would  produce  on  various  substances,  or  by  observing  that  portions  of  the 
chloride  had  repeatedly  become  black,  and  inquiring  into  the  circumstances. 
The  effect  of  the  urali  poison  might  have  become  known  either  by  administering 
it  to  animals,  or  by  examining  how  it  happened  that  the  wounds  that  the  Indians 
of  Guiana  inflict  with  their  arrows  prove  so  uniformly  mortal.  Now  it  is  manifest 
from  the  mere  statement  of  the  examples,  without  any  theoretical  discussion, 
that  artificial  experimentation  is  applicable  only  to  the  former  of  these  modes  of 
investigation.  We  can  take  a  cause  and  try  what  it  will  produce  ;  but  we  cannot 
take  an  effect  and  try  what  it  will  be  produced  by.  We  can  only  watch  till  we  see 
it  produced,  or  are  enabled  to  produce  it  by  accident. 

"  This  would  be  of  little  importance,  if  it  always  depended  on  our  choice  from 
which  of  the  two  ends  of  the  sequence  we  would  undertake  our  inquiries.  But 
we  seldom  have  any  option.  As  we  can  only  travel  from  the  known  to  the 
unknown,  we  are  obliged  to  commence  at  whichever  end  we  arc  best  acquainted 
with."  (Op.  cit.,  III.  vii.  4.) 


216  SUMMARY 

nature  under  natural  conditions,  spreads  over  a  great  number  of 
generations,  includes  the  largest  possible  number  of  families  and 
individuals,  and  results  eventually  in  definite  and  unmistakable 
changes  of  considerable  magnitude,  is  superior  to  any  inquiry  that 
can  be  devised  in  the  laboratory,  where  only  a  very  few  generations 
can  be  studied,  and  where,  since  our  power  of  observing  and 
measuring  the  lesser  variations  is  very  limited,  it  is  impossible  to 
observe  gradual  but  cumulative  change.  Provided  the  conditions 
of  accurate  observation  are  present,  I  think  no  thoughtful  biologist 
would  maintain  that  the  method  of  comparing  races  is  scientifically 
unsound.  He  might  insist,  however,  that  such  conditions  are  never 
met.  Undoubtedly  they  are  difficult  or  impossible  to  find  when 
we  study  natural  species  of  plants  and  lower  animals,  and  the 
study  of  domestic  varieties  is  misleading.  But  one  vast  field  of 
research  has  been  left  practically  untilled  by  students  of  heredity — 
the  human  species.  Here,  if  only  because  we  are  very  familiar 
with  the  subjects  of  observation  and,  therefore,  able  to  note  small 
differences,  our  knowledge  is  more  definite  and  precise  than  in  the 
case  of  any  other  species.  In  certain  particulars  at  least  we  are 
able  to  watch,  under  conditions  insuring  great  accuracy,  the 
tremendous  and  crucial  experiments  made  by  nature.1  We  may 
see  the  differentiation  of  races  occurring  in  such  a  way  as  enables 
us  to  trace  the  connexion  between  cause  and  effect.  In  a  real  sense 
we  may  extend  our  observations  over  hundreds  of  generations  and 
thousands  of  years,  for,  in  many  instances,  by  comparing  con- 
temporary races,  we  are  able  to  ascertain  exactly  the  ancestral 
type  of  a  race  that  has  changed  under  the  influence  of  a  precisely 
known  agent. 

355.  Occasionally  I  have  expressed  myself  very  positively  in 
the  preceding  pages,  and  this  will  be  displeasing  to  some  readers. 
But  the  evidence  on  which  my  conclusions  are  founded  is  given  in 
detail,  and  certitude  is  not  necessarily  dogmatic  nor  unscientific.  I 
have  tried,  as  best  I  am  able,  to  test  my  thinking.  I  can  only  ask 
my  readers,  while  bearing  the  evidence  in  mind,  to  think  out  the 
greater  problems  of  heredity  for  themselves — to  ask  themselves 
whether  evolution  is  ever  anything  but  adaptation,  whether  it  is 
possible  for  any  class  of  characters  to  be  in  any  true  sense  more 
innate  or  inheritable  than  any  other,  whether  it  is  conceivable  that 
the  development  of  the  individual  can  occur  otherwise  than  by 
recapitulation,  and  therefore,  whether  retrogression  can  ever  be 
other  than  reversion,  whether  the  main  mass  of  retrogression  is 

1See  footnote,  §  53. 


THE  GREATER  PROBLEMS  OF  HEREDITY        217 

due  directly  to  Natural  Selection,  and,  if  not,  whether  it  is  not 
possible  to  formulate  a  rational  theory  to  account  for  its  occurrence, 
whether  under  the  conditions  in  which  life  exists  variations  can  be 
other  than  spontaneous,  whether  the  power  of  growing  under  the 
stimulus  of  use  is  not  just  as  much  an  adaptation  as  the  power  of 
repairing  damaged  parts  under  the  stimulus  of  injury,  whether  the 
effect  of  conjugation  is  to  mix  parental  characters  as  marbles  are 
mixed  or  to  blend  them  as  colours  are  blended,  and  what  in  the 
one  case  or  the  other  is  the  function,  the  utility,  of- the  mixing,  and 
above  all  to  ask  themselves  whether  adaptation  is  due  wholly  to 
the  direct  action  of  Natural  Selection  or  in  large  part  also  to 
retrogression  occurring  in  the  complete  absence  of  selection. 

356.  These  are  the  greater  problems  of  heredity.  It  is  very 
possible  that  the  solutions  I  have  ventured  to  suggest  are 
erroneous,  but  I  am  very  sure  that  evidence  exists  which  should 
enable  us,  if  only  we  think  clearly,  closely,  and  comprehensively 
enough,  to  solve  them,  and  that  very  much  of  this  evidence  may 
be  obtained  from  a  study  of  human  beings.  To  that  study  we 
will  now  proceed. 


CHAPTER   XI 
HUMAN  DISEASES 

Neglect  of  the  human  species  by  modern  students  of  heredity — The  meaning 
of  racial  change — Progression  and  retrogression — The  present  evolution  of  man — 
Microbic  disease — Air,  water,  earth,  and  insect-borne  diseases — Toxins — Species 
that  produce  abundant  extra-cellular  toxins,  and  species  that  produce  little  or 
none — Phagocytes — The  duration  of  disease  and  its  cause — Acquired  immunity. 


F 


357.  "|  ^ORMERLY  man,  considered  as  a  whole,  as  a  bundle 
of  useful  and  related  characters,  occupied  a  good  deal 
of  scientific  attention.  Darwin  traced  his  descent. 
Huxley  sought  to  fix  his  place  in  nature.  Spencer,  Romanes,  and 
Lewes  dealt  with  his  mental  evolution — mainly  from  the  stand- 
point of  Lamarckism.  But  of  late  years  the  turn  given  by  fashion 
to  biological  work  has  been  unfavourable  to  an  adequate  study  of 
him.  He  cannot  be  dealt  with  experimentally,  at  any  rate  not  by 
inter-varietal  crossings  arranged  by  the  worker.  The  results  of 
crossings  arranged  by  nature  have  not  to  my  knowledge  attracted 
much  attention  except  in  so  far  as  is  indicated  by  the  surprising 
statement  that  human  skin-colour  is  the  only  feature  which  crossed 
varieties  blend  perfectly.  The  alternative  inheritance  of  various 
human  abnormalities  has  been  noted.  Biometricians  have  devoted 
rather  more  attention  to  man  than  Mendelians  and  mutationists. 
They  have  endeavoured,  on  the  one  hand,  to  ascertain  the  degree 
of  correlation  between  certain  of  his  parts,  and  on  the  other  to 
discover  the  extent  to  which  some  of  his  variations  tend  to  be 
inherited.  Only  a  very  small  portion  of  the  total  field  has  been 
covered,  however,  and  some  biometric  work  is  vitiated  by  a 
failure  to  distinguish  adequately  between  '  innate '  and  '  acquired  ' 
characters.1  The  importance  of  drawing  this  distinction  will 
become  manifest  as  we  proceed. 

358.  While  studying  heredity  in  connection  with  human  beings 
we  shall  have  to  depend  largely  on  patent  facts — quite  indisput- 
able facts,  however — collected  by  simple  observation,  and  largely 
also  on  the  special  method  of  comparing  races.  The  data  left 

^See  §§  706  et  seq. 

218 


THE  UTILITY  OF  HUMAN  CHARACTERS          219 

unused  hitherto  are  extremely  rich  and  suggestive,  and  will  furnish, 
not  only  materials  from  which  may  be  drawn  some  conclusions, 
which  to  me  seem  indisputable,  but  also  the  means  of  testing  the 
thinking  by  which  they  are  reached.  We  shall  be  embarrassed, 
however,  by  the  mass  of  error  which  has  collected  around  the 
subject.  In  all  ages  the  thoughts  of  men  have  been  concentrated 
on  themselves,  their  parents,  children,  and  fellows,  and  traditions 
have  arisen  which,  though  far  from  the  truth,  are  yet — owing  to  a 
human  mental  characteristic  of  the  highest  general  utility l — very 
hard  to  break  down. 

359.  The  reader  must  bear  in  mind  certain  conclusions  which 
we  have  already  reached.     Like  other  living  beings,  man  is  mani- 
festly a  bundle  of  adaptations.     Indeed,  since  he  is  better  known, 
he  is  more  manifestly  a  bundle  of  adaptations  than  any  other 
type.       Beyond  doubt  some  human   characters  have   no   utility. 
Of  these  a  few  may  be  by-products  of  evolution  correlated  to  more 
useful  traits,  the  only  one  of  the  kind  of  any  importance  known 
to   me  being   susceptibility  to   the  charm  of  alcohol  and   other 
narcotics.     Others,  such   as   the   colour  of  blood   and   bone,  are 
chance  qualities  of  useful  characters — chance  in  the  sense  that  in 
all  probability  they  have  not   arisen  through  selection.     These, 
however,  do  not  enter  into  the  account ;   of  necessity  blood  and 
bone  must  have  some  colour.2     Yet  others  have  lost  their  utility, 
and  have  become  or  are  becoming  vestigial.     Speaking  generally, 
in  only  a  few  instances  has  the  past  or  present  utility  of  a  character 
not  been  ascertained.     There  can  be  no  doubt,  therefore,  that  the 
immense   majority  of  human   characters,  whether   in   the   trunk, 
limbs,  or  head,  are  adaptations.     The  growth  of  modern  physio- 
logy implies  merely  an  increased  power  of  interpreting  human  traits 
in  terms  of  their  utilities. 

360.  We  also  reached  the  conclusion  that  all  adaptation  has 
resulted  from  the  combined  action  of  progression  and  retrogression, 
the  former  being  a  product  of  selection,  the  latter  usually  following 
cessation  of  selection.     Given  progression  as  an  accompaniment 
of  selection,  and  retrogression  as  a  correlate  of  cessation  of  selec- 
tion,  close   adaptation   is   obviously  inevitable.      We  concluded, 
further,  that  this  theory  of  evolution  has  for  its  necessary  corollary 
a  theory  of  heredity  which  supposes  (i)  that  the  great  mass  of 
variations  are  spontaneous,  and,  therefore,  (2)  that  the  germ-plasm, 
so  far  as  its  hereditary  tendencies   are  concerned,  is  highly  in- 
susceptible  to   the   direct   action   of  the   environment ;   (3)   that 

1  See  §  663.  »  See  §  649. 


220  HUMAN  DISEASES 

retrogressive  variations  tend  to  predominate  over  progressive 
variations;  and  (4)  that  these  three  fundamental  characters  of 
living  beings  are  themselves  adaptations  which  have  resulted  from 
Natural  Selection. 

361.  Nearly  all  biologists  at  the  present  day  accept  the  theory 
of    Natural    Selection;    but    some    accept   it   with   considerable 
reservations,  and  none,  as  far  as  I  am  aware,  accept  it  in  the  form 
I    have   suggested.      For   example,    the   elimination    of    useless 
characters  (variations  and  old-established  parts)  is  still  generally 
attributed    to    reversed    selection.        Sometimes    progression    is 
thought  to  result  from  an  inherent  growth-force  that  is  only  kept 
in  check  by  Natural  Selection,  which  therefore  moulds  the  race 
by  planing  away  superfluities.      In  other  words,  progression  is 
thought  to  result,  not  from  selection,  but  from  a  natural  tendency 
for  progressive  variations  to  predominate  over  retrogressive  varia- 
tions.     According   to   this   theory,   therefore,   all   species   would 
progress   were  it  not  for   Natural   Selection.      There   is  massive 
evidence,   however,  that  this  view,  which  appears  to  be   especi- 
ally  popular   amongst   the   supporters   of   the   mutation   theory, 
is   mistaken.      All   parts,   for   example   vestigial   parts   and   the 
special  features  of  prize  domestic  breeds  (e.g.  race-horses),  which 
have  no  survival  value,  tend  to  disappear  on  cessation  of  selection, 
and  we  have  only  to  observe  Natural  Selection  in  actual  opera- 
tion to  perceive  plainly  that  its  special  role  is  the  causation  of 
progression.1 

362.  My  excuse  for  the  positive  attitude  I  assume  must  be 
that  I  offer,  in  the  chapters  that  now  follow,  easily  verified  and, 
I  think,  very  conclusive  evidence  of  Natural  Selection  in  actual 
operation ;  whereas  the  opinions   I  controvert  are  founded  on  a 
consideration    of   lower    animals    and     plants,    amongst    which, 

1  As  a  rule  the  idea  that  one  or  the  other  kind  of  variations  tends  to  predominate 
is  implied  rather  than  expressly  stated  in  the  theories  of  biologists.  The  problem 
has  not  often  been  especially  formulated.  I  think  most  students  of  evolution 
believe,  more  or  less  vaguely,  that  progressive  and  retrogressive  variations  about 
balance  one  another.  This  view,  however,  leaves  unexplained  the  retrogression 
of  parts  that  have  no  selection  value.  Weismann's  theory  of  Panmixia  implies 
that  retrogressive  variations  predominate,  and  he  has  attempted  to  account  for 
the  fact  by  his  hypothesis  of  Germinal  Selection.  The  view  I  have  ventured  to 
set  before  the  reader  differs  from  his  merely  in  that  I  attribute  the  predominance 
to  a  tendency  evolved  by  Natural  Selection,  and  do  not  speculate  on  the 
mechanism  of  processes  in  the  germ-plasm  concerning  which  I  have  no  data. 
Mutationists  and  Mendelians  ignore  retrogression.  At  any  rate,  the  subject  is 
not  to  my  knowledge  mentioned  in  their  works.  Indeed  the  fact  that  retro- 
gression constantly  occurs  on  cessation  of  selection  is  not  only  quite  ignored, 
but  also  is  by  implication  controverted  by  many  of  them.  See  §  285. 


EVOLUTION  AND  RACIAL  CHANGE  221 

admittedly,  when  wild,  the  operation  of  Natural  Selection  cannot 
be  observed,  and  amongst  which,  when  domesticated,  it  is  largely 
in  abeyance.  Very  many,  if  not  all,  biologists  believe,  also,  that 
variations  commonly  result  from  the  direct  action  of  the  environ- 
ment on  the  germ-plasm,  and  found  this  opinion  mainly  on 
experimental  evidence — that  is,  on  evidence  obtained  from  plants 
and  animals  which  have  been  placed  under  conditions  abnormal 
to  the  race  and  to  the  individual.  But,  as  already  noted,  such 
experiments  prove  merely  that  it  is  sometimes  possible  to  devise 
conditions  in  which  the  germ-plasm,  like  other  living  structures, 
is  injured  and  yet  not  killed.  They  do  not  demonstrate  that  the 
variations  of  a  species  in  its  normal  environment  commonly  arise 
in  this  way.  It  is  impossible  to  prove  a  universal  negative,  and 
therefore,  if  only  for  that  reason,  we  cannot  demonstrate  that 
variations  are  not  so  caused.  Indeed,  I  do  not  maintain  anything 
of  the  kind.  I  insist  merely,  on  grounds  which  I  believe  are  quite 
unassailable,  that  the  conditions  of  life  are  such  that  it  could  not 
persist  on  earth  unless  the  vast  majority  of  variations  were  spon- 
taneous— unless  the  germ-plasm  were  highly  insusceptible  to  the 
direct  action  of  the  environment.  We  have  already  dealt  with 
some  of  the  evidence.  But  it  will  be  well  worth  while  to  consider 
it  more  at  length,  especially  as  we  shall  thereby  gain  an  insight 
into  man's  recent  evolution,  and  be  brought  in  contact  with  some 
practical  problems  of  great  importance. 

363.  We   reached  one  other  conclusion  which  bears  on  our 
present   task,   namely,   that   the    predominance   of    retrogressive 
variations  is  less  marked  in  the  case  of  old-established  than  of 
more  recently  evolved  characters.      This,  also,  is  an  adaptation. 
The    circumstance    that    continued    selection    tends    to    render 
characters   more  stable  carries  the  advantage  that  ultimately  a 
minimum  of  selection  suffices  to  maintain  a  useful  trait.     The 
mortality  resulting  from  selection   is   thus   diminished,   and   the 
selection  (and  therefore  the  progression)  of  other  useful  characters  is 
rendered  possible  without  the  death-rate  exceeding  the  birth-rate. 

364.  Before   discussing   human   heredity,    it   is   necessary   to 
define  carefully  the  meanings  we  attach  to  such  terms  as  '  evolu- 
tion,' 'racial  change,'  and  the  like.     They  have  both  been  used, 
especially  by  popular  writers,  to  indicate  two  quite  separate  sets 
of  phenomena,  which,  if  we  wish  to  avoid  endless  confusion,  must 
be  clearly  distinguished.      On  the  one  hand  are  germinal  or  truly 
innate  changes ;  on  the  other  are  changes  due  to  a  differential 
play  of  stimuli.    Thus  the  colour  difference  between  Scandinavians 


222  HUMAN  DISEASES 

and  negroes  has  a  germinal  origin,  whereas  that  between  English- 
men at  home  and  in  India  is  merely  acquired.  So,  also,  the  mental 
difference  between  a  naturally  intelligent  race  and  a  naturally 
dull  one  is  not  the  same  as  that  between  two  races,  one  of  which 
has  been  rendered  more  intelligent  than  the  other  by  a  better 
system  of  mental  training.  By  such  terms  as  evolution,  racial 
change,  progression,  and  retrogression  we  shall  always  in  the 
present  work  imply  germinal  change.  By  so  doing  we  shall 
follow  an  established  biological  custom,  which,  as  a  rule,  is  in- 
fringed only  when  the  writer  mistakes  acquirements  for  germinal 
changes.  It  is  often  very  difficult  to  disentangle  the  two,  and  the 
attempt  to  do  so  will  form  a  main  part  of  our  future  task. 

365.  Accepting  for  the  moment,  then,  the  hypothesis  that  racial 
progression  is  invariably  due   to  selection,  whereas  retrogression 
results,  as  a  rule,  from  cessation  of  selection,  it  is  evident  that,  if 
we  seek  to  ascertain  the  direction  in  which  a  human  race  is  under- 
going germinal  change,  we  must  study  the  causes  of  death.     If  we 
find   that  inferiority  in  any   character  results   in   a   considerable 
mortality,  or  in  a  diminution  of  the  average  number  of  offspring, 
we  may  assume  that  in  all  probability  the  trait   in  question  is 
undergoing   progression ;    for   here   we   have    evidence   that   the 
race  is  not  yet  well  adapted  to  the  environment.     On  the  other 
hand,  total  loss  of  utility,  implying  as  it  does  cessation  of  selection, 
implies  also  a  tendency  to  retrogression. 

366.  During  the  last  few  thousands  of  years  man  has  altered  his 
environment  in  one  very  important  way  and  in  that  one  way  only. 
He  has  become  increasingly  civilized.     Civilization  implies,  on  the 
one  hand,  protection  from  most  of  the  dangers  which  beset  wild 
animals,   and,   therefore,    cessation  or    diminished    stringency   of 
selection  along  those  lines  of  evolution  which  raised  man  in  the 
animal  scale  and  ultimately  made  him  human.     On  the  other  hand, 
it  implies  a  fuller  command  over  the  resources  of  nature,  which  in 
turn  implies  a  more  abundant  and  regular  supply  of  food,  and  that 
again  implies  a  more  crowded  and  settled  population.     The  problem 
before  us  is  whether  this  vast  alteration  of  environment  has  resulted 
in    appreciable   germinal    change  —  in   appreciable  progression    or 
retrogression.     Civilized  man  differs  in  many  striking  ways  from 
the   modern   savage,   and   probably,  therefore,   from   his   remote 
ancestors.     Our  task  is  to  ascertain  how  much  of  this  difference  is 
innate  and  how  much  due  merely  to  a  differential  play  of  stimuli. 
We  shall  study  first  man's  physical  characters,  reserving   mind 
for  a  later  section  of  this  book. 


HUMAN  PROGRESSION  AND  RETROGRESSION     223 

367.  Popularly,  and  even  by  most  scientific  men,  the  human 
race   is   supposed   to   be  undergoing   progression  in  all    sorts  of 
directions.     Others  suppose  that  cessation  of  selection  is  resulting 
in  general  retrogression.     But  clearly,  as  in  other  species,  the  great 
majority   of   human    physical    characters  are   merely   stationary. 
They  are   selected,  but   only   to  an  extent  which   maintains  an 
efficiency  previously  established.     They  fit   the  race  sufficiently 
well  to  the  environment,  and  only  marked  defect  usually  results  in 
a  failure  to  rear  offspring.     Judging  from  ancient   remains    and 
from  a  comparison  with   modern   savages,   civilised    man  differs 
little,  if  at  all,  from  his  remote  ancestors  in  hands,  feet,  blood,  bones, 
heart,    lungs,   and    the   like.     Doubtless,   owing   to   accidents   of 
survival,  to  sexual  selection,  or  to  migration  which  brings  different 
sets   of  selecting   agencies  into   play,  all  races  have   undergone 
some  structural  changes  ;  but  these  are  comparatively  unimportant. 
In  obvious  physical  features,  the  features  by  which  biologists  are 
accustomed  to  measure  physical  change,  humanity  as  a  whole  has 
undergone   little   innate  alteration  during   the  few   thousands  of 
years   of  civilisation.     We  are  said  to  be  more  bulky  than  our 
ancestors  of  six  or  seven  centuries  ago,  but  there  is  no  evidence 
that    during   the   interval    big    individuals   have    been    specially 
selected  for  survival.     Probably,  therefore,  the  increase  in  size  is 
due  merely  to  environmental  changes,  such  as  improved  nutrition 
and   treatment   of  the   young,   which   permits   better   individual 
development.     An  analogous  case  is  that  the  modern  girl  of  the 
higher  classes  is  taller  on  the  average  than  her  grandmother,  and 
the  modern  field  labourer  than  the  factory  hand.     Some  modern 
savages   are    taller   on   the   average   than   the   members   of  any 
civilized  race,  and  some  skeletons  of  the  Stone  Age  are  those  of 
large  men  with  well  developed  crania. 

368.  Of  retrogression,  also,   there  is   little  positive   evidence. 
Thus,  when  suitably  trained,  civilized  men  appear  to  be,  on  the 
whole,  just  as  keen  of  sight  and  hearing  and  as  capable  of  enduring 
fatigue  as  savages.     The  Boers  and  Australian  whites  are  cases 
in  point.     It  is  only  when  we  compare  man  to  the  nearest  lower 
animals  that  we  seem  to  obtain  positive  evidence.     Some  of  his 
senses,    his   hearing   and    sense   of    smell,   for   example,   appear 
weaker.     His  jaws  and  teeth  certainly,  and  probably  his  digestive 
apparatus,   have   undergone   retrogression.     He   is    less    able    to 
masticate    and    assimilate    the    raw    coarse   food   on   which    his 
ancestors  subsisted.     But,  even  here,  it  is  probable  that  much  is 
attributable  to  the  direct  action  of  the  environment  on  the  developing 


224  HUMAN  DISEASES 

structures.  The  senses  of  hearing  and  touch  and  possibly  of  smell 
become  very  acute  in  the  blind,  and  civilized  children  are  supplied 
with  such  Jsoft  food  that  their  jaws  are  not  stimulated  to  the 
utmost  possible  development.  Their  teeth,  which  owe  nothing  to 
the  stimulus  of  use,  and  therefore  attain  their  full  size,  are  crowded 
irregularly  together  in  the  small  jaws,  and  while  retaining  fragments 
of  fermentable  food  in  their  interstices,  are  not  cleansed  by  the 
tough  fibrous  substances  which  form  a  prominent  part  of  the  diet 
of  savages.1  They  are  therefore  particularly  exposed  to  decay. 
African  negroes  have  magnificent  teeth ;  their  relatives  in  America 
suffer  much  from  caries ;  yet  only  a  few  generations  separates  the 
American  black  from  a  savage  ancestry. 

369.  It  follows  that   though  man   has  not   now   so   strenuous 
nor  so  active  a  struggle  for  mere  existence  as  formerly,  though 
exceptional  strength,  activity,  endurance,  beauty,  or  cleverness  do 
not  at   the  present  day  imply   as   a  rule  more  than  an  average 
number  of  offspring ;  though  men  perish  so  very  rarely  and  in  such 
a  haphazard  manner  from  wild  beasts  and  enemies  and  from  priva- 
tion that  there  is  no  real  selection,  though  modern,  weapons  of  war 
do  not  discriminate  between  the  fit  and  the  unfit  in  battle,  yet  since 
man's  ancient  characters  are  firmly   established   and   since   con- 
spicuous defect  still  acts,  on  the  average,  as  a  bar  to  offspring,  he 
has   undergone   little   retrogression.     Of  progression  on   lines  of 
ancient  characters  there  is  no  valid  evidence. 

370.  Nevertheless,   since  men  still   perish  in   great  numbers 
before  contributing  their  full  quota  of  offspring  to  the  race,  some 
sort  of  selection  is  occurring.     Our  facilities  for  ascertaining  its  precise 
nature  are  particularly  good.     Indeed,  this  is  the  only  instance  in 
nature   in   which   the   operations   of  Natural   Selection   may   be 
observed,  not  merely  guessed  at.     In  every  civilized  country  tables 
of  mortality  are  compiled  from  which  we  may  learn  exactly  the 
causes  which  eliminate  the  inhabitants  of  civilized  states,  the  number 
of  deaths  due  to  each  cause,  and  the  ages  of  those  who  perish.     In 
the  vast  majority  of  instances  civilized  men  die  of  disease?     Disease 

1  J.  Sims  Wallace,  Decay  in  Teeth  (London,  Churchill). 

*  In  England  and  Wales  520,031  people  died  during  the  year  1905.  Of  these 
19,437  perished  of  violence,  mainly  the  result  of  accident  in  flood  or  field  or  in 
mines.  Among  the  violent  deaths,  however,  were  133  from  homicide,  17  from 
execution,  and  3  from  battle;  21  persons  died  from  starvation,  2638  committed 
suicide,  but  probably  many  of  these  suffered  from  physical  or  mental  diseases ; 
813  are  said  to  have  died  of  plague.  The  remaining  half  million  perished  almost 
exclusively  from  disease,  including  from  tuberculosis  55,759,  pneumonia  44,367, 
bronchitis  38,9 15,  cancer  30,221,  diarrhoea  20,534,  measles  11,076,  whooping-cough 
8709,  influenza  6953,  diphtheria  5459,  scarlet  fever  3834,  cirrhosis  of  liver  4008, 


HUMAN  EVOLUTION  225 

then  is  the  only  stringently  selective  agent  amongst  civilized 
men.  The  types  it  weeds  out  are  those  that  are  weak  against  disease, 
the  survivors  are  those  that  are  resistant  to  disease  :  it  follows  that 
the  only  racial  progression,  certainly  the  only  considerable  racial 
progression,  that  civilized  human  races  undergo  is  one  against 
disease. 

371.  This  conclusion  is  likely  to  be  controverted,  and  by  none 
more  strenuously  than  by  students  of  evolution,  most  of  whom  have 
devoted  attention  exclusively  to  such  peculiarities  of  shape,  colour, 
size,  and  the  like,  as  mark  obvious  differences  between  species  and 
varieties,  and  who  have  not  taken  into  account  the  actual  causes 
which  eliminate  human  beings   under   conditions   of  civilization. 
But,  either  heredity  is  of  the  same  nature  in  man  as  in  other  species, 
or  it  is  not     If  it  is  not,  how  shall  we  account  for  the  miracle  of 
adaptation,   and  for  the  constant  retrogression  of  useless  parts  ? 
Man,  while  supplying  indubitable  evidence  of  progression  when 
under  selection,  affords  no  clear  instance  of  real  progression  in 
the  lack  of  it.     If  retrogression  constantly  accompanies  cessation 
or  diminishing  stringency  of  selection,  it  follows  that  only  selec- 
tion, which  is  sufficiently  stringent,  can  be  a  cause  of  progression. 
Amongst  civilized  men,  then,   what  are  the  causes  of  stringent 
selection  other  than  disease  ?      What   types   of   men    are    being 
eliminated?     In  what  direction  precisely  is  progression  occurring? 
I  have  known  men  who  have  attempted  to  answer  these  questions, 
but  I  have  never  known  one  who  succeeded.     At  best  they  have 
merely  guessed  vaguely  at  lines  of  elimination  the  existence  of 
which  they  were  unable  to  demonstrate,  or  indicated  lines  of  progres- 
sion which  they  could  not  show  were  other  than  acquirements 
due  to  the  better  development  (through  improved  conditions)  of 
the  descendants  as  compared  with  the  ancestors. 

372.  The  reader  has  only  to  refer  to  his  own  experience  of  life 
to  perceive  that  not  a  single  character  save  power   of  resisting 
disease  is  stringently  selected.     Except  in  extreme  cases  such  traits 
as,  for  example,  shortness  of  stature,  muscular  weakness,  or  lack 
of  beauty  or  intellect,  are  not  serious  bars  to  offspring.     But  great 
susceptibility   to   disease   is   an    absolute   bar,  for  the  individual 
perishes  in  early  life.     Relative  susceptibility  is  a  lesser  obstacle, 
but   individuals   characterized    by   it   are   seriously  handicapped, 
and  22 1 1  of  alcoholism.     Of  the  total  number  of  deaths  280,302  were  of  people 
under  45  years  of  age,  and  239,729  of  older  people;   18,871  infants  died  because 
prematurely  born,  2343  of  teething,  and  12,933  of  convulsions.     Doubtless  in 
the  last  three  categories,  disease,  parental  (through  causing  injury  in  utero)  or  filial, 
was  a  potent  factor. 

15 


226  HUMAN  DISEASES 

and  frequently  perish  without  leaving  offspring.  It  is  conceivable, 
of  course,  that  insusceptibility  to  this  or  that  disease  may  be 
correlated  to  some  other  and  apparently  unrelated  character  such 
as  height  or  colour  or  peculiarity  of  disposition,  which  therefore 
would  undergo  concurrent  evolution  as  the  race  grew  resistant  to 
the  disease.  But,  speaking  comparatively,  correlated  characters  of 
this  sort  are  very  rare,  and  the  study  of  disease  has  revealed  none, 
though  the  opportunities  for  observation  are  excellent ;  for  we  are 
able  to  compare  races  which  are  very  susceptible  to  this  or  that 
disease  with  races  which  are  highly  resistant.  Very  certainly  the 
comparison  of  such  races  reveals  no  such  correlations. 

373.  Some  biometric  investigations,  it  is  true,  seem  to  indicate 
lines  of  progression  and  retrogression  other  than  that  related  to 
disease ;  but  the  data  on  which  they  are  founded  are  very  scanty 
as  compared  with  the  evidence  that  can  be  gleaned  from  tables  of 
mortality ;  they  cover  only  a  few  generations,  and  make  no  very 
serious  attempt  to  distinguish  real  variations  from  acquirements. 
In   the   case   of  disease  we  are  able  not  only  to  obtain  precise 
numerical  information  on  a  large  scale  as  to  the  causes  of  death,  but 
it  is  in  our  power  to  test  such  theories  of  evolution  as  we  may  found 
on  that  information  in   a  very  decisive  way,  by  comparing  races 
which  have  long  and  severely  suffered  from  any  disease  with  races 
that  have  been  newly  introduced  to  it.     By  this  means  we  may 
discover,  for  example,    whether  the  selective   elimination   which 
we  suspect  to  be  a  cause   of  progression   is  a  true   cause,   and 
whether  the  progression,  if  any,  has  correlated  to  it  the  growth  of 
some  other  trait. 

374.  Of  deaths  due  to  disease  by  far  the  greater  number  are 
caused  by  microbic  maladies,  or  by  the  abuse  of  such  narcotics  as 
alcohol  and  opium.     Probably,  with  the  exception  of  violent  death, 
which  is  non-selective,  and  cancer,  which  occurs  mainly  during 
advanced  life,  and  therefore  exercises  little  or  no  selection,  there 
are  no  other  very  important  causes  of  elimination.     Thus  of  the 
76,844  deaths  which  occurred  in  England  and  Wales  during  the 
year  1905  from  diseases  of  the  heart  and  blood-vessels,  it  is  pro- 
bable that  the  great  majority  had  a  microbic  or  alcoholic  origin, 
especially  in  the  case  of  people  who  died  before  the  end  of  the 
reproductive  period.     Doubtless,  also,  the  deaths  of  very  many  of 
the  18,871  infants  who  perished  because  prematurely  born,  or  who 
died  of 'convulsions '(12,53  3),  or  of  teething  (2343),  were  due  to  the 
same  causes  acting  directly  on  the  children  or  through  the  parents. 

375.  Half  a  century  ago  the  nature  of  microbic  diseases  was 


MICROBIC  DISEASES  227 

unknown.  Thus  when  I  was  a  boy  in  India,  troops  were  marched 
across  the  wind  to  new  camps  in  the  endeavour  to  avoid  cholera.  At 
the  present  day  even  school  children  have  some  idea  of  the  agencies 
which  cause  them.  Sanitary  authorities  work  with  a  knowledge 
of  cause  and  effect,  which  is  daily  growing  more  exact,  and  hardly 
a  year  passes  but  some  disease  hitherto  mysterious  is  traced  to  a 
microbic  origin.  As  a  consequence,  both  the  prevention  and  treat- 
ment of  disease  are  becoming  more  rational.  Men  hope  with  good 
reason  to  utterly  abolish  such  terrible  maladies  as  malaria,  the 
treatment  of  which  was  formerly  limited  to  attempts  to  cure,  and 
which  were  supposed  to  be  as  irremovable  a  part  of  the  natural 
features  of  a  country  as  its  mountains  and  rivers. 

376.  Human  zymotic,  infectious,  or  microbic  diseases — tuber- 
culosis, scrofula,  lupus,  influenza,  measles,  common  cold,  bronchitis,1 
chicken-pox,   smallpox,   syphilis  (great  pox),  and  other  venereal 
diseases,  whooping-cough,  diphtheria,  pneumonia,  rabies  (hydro- 
phobia), tetanus  (lock-jaw),  enteric  fever  (typhoid),   scarlet   fever 
(scarlatina),    typhus,    leprosy,  septicaemia,     peritonitis,     malaria, 
dysentery,  epidemic  diarrhoea,  cholera,  yellow  fever,  plague,  sleep- 
ing-sickness, erysipelas,  rheumatic  fever,  puerperal  fever,  abscess, 
meningitis,    cerebro-spinal    (spotted)    fever,    mumps,    opthalmia, 
phlebitis,   tonsilitis   (quinsy),  beriberi,    dengue,    blackwater   fever, 
Malta  fever,  and  a  host  of  others — are  caused  by  the  invasion  of 
the  body  of  man,  and    the   multiplication   within   his   blood   or 
tissues  of  various  species   of  microbes,  minute  unicellular  plants 
or  animals,  which  find  their  nutriment  in  him.     Very  many  of 
these   parasitic    disease-producing   (pathogenic)   organisms   have 
been  seen  under  the  microscope.     In  many  cases  the  causal  con- 
nexion of  a   species  with  the  disease  to  which  it  gives  rise  has 
been  demonstrated  by  an  experimental  inoculation  of  non-infected 
animals,  and  at  the  present  day  the  doubts  of  a  medical  man  as  to 
the  nature  of  the  disease  he  is  treating  are  often  solved   by  the 
bacteriologist  with  his  test-tube  and  microscope. 

377.  Some  zymotic  diseases   are    comparatively    rare.      The 
microbes  may  be  uncommon,  as  those  of  spotted  fever  ;  or  they  may 
not  easily  find  entrance  into  the  living  body,  as  those  of  lock-jaw, 
or  they  do  not  readily  establish  themselves  in  the  healthy  tissues  of 
the  normal  individual,  as  those  of  septicaemia.       Others  are  so 
prevalent  in  some  countries,  and  gain  entrance  to  the  body  so 
readily  that  no  man  escapes  infection  unless  he  is  "  by  nature " 

1  See  The  Sixty-eighth  Report  of  the  Registrar  General  of  Births,  Deaths  and 
Marriages,  p.  cxiii. 


228  HUMAN  DISEASES 

immune,  or  death,  unless  he  possesses  a  high  degree  of  resisting 
power — for  example,  the  microbes  of  measles,  common  cold, 
whooping-cough,  and  tuberculosis  in  England,  malaria  in  West 
Africa,  and  dysentery  in  India. 

378.  The   species   of    microbes    that   cause   disease    in    man, 
numerous  as  they  are,  form  but  a  fractional  part  of  the   total 
number  of  parasitic  species  which  afflict  animals  and  plants,  and 
these  again  are  few  as  compared  to  the  multitudes  of  unicellular 
organisms  which  find  their  nutriment  in  non-living  matter.     Some 
of  the  latter,  the  saprophytes,  exist  on  the  dead  bodies  of  animals 
and  plants,  which  but  for  them  would  cumber  the  earth  unchanged. 
Each   species   fits   its   own   particular  niche  in    nature.     All  are 
capable  of  extremely  rapid  multiplication,  a  circumstance  which 
not   only   secures   the    persistence   of  the   species,   but   provides 
material  for  selection,  and,  therefore,  facilities  for  quick  adaptation 
to  changing  environments. 

379.  Of  the  microbes  which  cause  'human  disease,  some,  for 
example  those  of  typhoid,  cholera,  dysentery,  and  diarrhoea,  enter 
the  body  in  water  or  other  nutritive  substances.    Since  infected  water 
is  a  very  common  vehicle,  they  are  usually  termed  water-borne. 
The  microbes  of  other  species  are  commonly  inhaled.     The  types 
which  use  this  latter  method  of  entrance  are  usually  very  minute ; 
they  float  in  the  air  like  fine  dust,  and  therefore  are  termed  air- 
borne.    Such  are  the  microbes  of  influenza,  smallpox,  common 
cold,   and   many  other   maladies.      Few   of   these   types,  owing 
doubtless  in  part  to  their   small   size,  have  been   seen.     While, 
seemingly,  the  microbes  of  all  air-borne  species  are  very  minute, 
small  size  is  of  course  not  their  only  means  of  adaptation  to  their 
method  of  infection.     For  example,  it  appears  likely  that  their 
mode   of  existence  in  the  body  is   such  that  they  are  exhaled 
directly  into  the  atmosphere  by  the  breath  of  the  sufferer,1  where- 
as the  microbes  of  the  water-borne  maladies  pass  from  him  mainly 
in  solid  or  liquid  excreta.     The  air-borne  microbes,  owing  to  their 
mode  of  conveyance  and  their  enormously  rapid  rate  of  multiplica- 

1  There  is  evidence  that  the  microbes  of  such  diseases  as  scarlet  fever  may  be 
carried  into  the  atmosphere,  or  may  infect  the  clothes  through  dried  particles 
from  the  surface,  especially  in  the  later  stages  of  the  disease.  In  the  latter  case, 
the  microbes  are  beyond  the  reach  of  the  phagocytes  or  the  enzymes  (see  §§  385-6). 
This  is  probably  the  explanation  of  the  well-known  fact  that  a  person  recovered 
from  scarlet  fever  is  often  infective  to  his  fellows  for  a  period  which  is  long  com- 
pared  to  that  which  is  the  rule  with  common  cold  or  influenza.  In  its  earlier 
stages  it  is  practically  certain  that  scarlet  fever  infects  through  the  breath. 
Certainly^it  is  very  infective  before  there  is  any  desquamation  of  the  skin. 


MODES  OF  INFECTION  229 

tion,  are  exceedingly  infective.  Consequently,  the  immediate 
neighbourhood  of  a  person  attacked  by  them  is  dangerous  to 
susceptible  people.  On  the  other  hand,  a  person  suffering  from  a 
water-borne  malady  may  be  approached  with  safety,  the  danger 
lying  in  the  source,  the  nutriment  (water  or  food)  whence  the 
disease  was  acquired,  or  in  the  solids  or  liquids  he  may  excrete. 
Some  species  of  microbes  which  enter  by  the  breath,  for  example, 
those  of  tuberculosis,  are  comparatively  large  and  heavy.  They 
fall  to  the  ground,  whence,  the  sputum  in  which  they  are  contained, 
having  dried,  they  are  swept  up  with  particles  of  dust  by  currents 
of  air.  They  are,  therefore,  termed  earth-borne.  As  compared  to 
the  air-borne  types  they  are  in  lesser  multitudes  in  the  air  sur- 
rounding a  sufferer  whose  neighbourhood,  therefore,  especially 
in  well-ventilated  spaces,  is  not  so  charged  with  infection.  The 
microbes  of  other  earth-borne  diseases,  for  example  those  of 
tetanus,  gain  entrance  through  abrasions  in  the  skin. 

380.  Yet   other   species,    for   example   those   of  malaria   and 
sleeping-sickness,   are  insect-borne ;    that  is,    they   are   conveyed 
from  an  infected  to  a  susceptible  person  by  blood-sucking  insects. 
Lastly,  some  species,  for  example  those  which  cause  the  venereal 
diseases,  pass   by   direct   contact   from   one    person    to   another. 
Rabies,  which  is   one  of  these  '  contagious '  maladies,   is  hardly 
ever,  if  ever,  communicated  by  one  human  being  to  another,  but 
is  acquired  through  the  bite  of  an  infected  individual  belonging 
to  some  lower  type  of  mammal. 

381.  The  terms  contagious,  earth,  air,  water,  and  insect-borne 
are   convenient   as    indicating   common   modes   of  infection,  but 
they  do  not  necessarily  imply  that  each  of  the  various  diseases 
infects  in  only  one  way.     For  instance,  scarlet  fever   is  usually 
air-borne  and  tuberculosis  earth-borne;  but  it  is   probable  that 
both  are  sometimes  conveyed  by  milk.     During  the  war  in  South 
Africa,  enteric  fever  seems  to  have  been  spread  by  dust  storms, 
or   by    flies   which  had  been   feeding   on    excreta.     In  England 
also  flies  are  common  vehicles  for  infantile  diarrhoea  during  the 
summer  months. 

382.  The   bodies   of    the    higher    animals   consist   mainly  of 
nutritive  substances,   and  would   be  happy  hunting-grounds   for 
microbic  types  if  they  possessed  no  means  of  defence.    Though  the 
skin  and  food  and  air  passages  of  the  higher  animals  swarm  with 
unicellular  organisms,  these  are  absent  from  the  tissues  of  a  healthy 
individual.     The  fact  that  the  microbes  of  disease  are  often  able 
to   break   down  the  defence  and  enter  the  tissues,  whereas  the 


230  HUMAN  DISEASES 

harmless  types  are  unable  to  do  so,  points  to  the  fact  that  the 
former  have  special  means  of  offence.  When  studying  heredity 
in  relation  to  disease,  it  is  necessary  to  know  something  of  these 
means  of  offence  and  defence,  otherwise  we  are  liable  to  fall  into 
the  error,  which  vitiates  so  much  speculation  on  the  subject,  of 
mistaking  somatic  modifications  for  germinal  changes. 

383.  Just  as  the  different  species  of  microbes  have  different 
means  of  entering  the  body,  so,  when  once  the  entrance  is  affected, 
they  tend  to  select  different  parts  or  tissues  of  the  body  for  their 
habitation.      Some,   as   those    of    malaria   and    probably   of    all 
'general'    diseases    such    as    influenza,    smallpox,    measles,    and 
scarlet  fever,  inhabit  the  blood  or  lymph.     They  multiply  with 
great  rapidity,  and  penetrate  to  every  region.     On  the  other  hand, 
tuberculosis   especially  affects   the  lungs  and  lymphatic  glands, 
more  rarely  the  membranes  of  the  brain,  the  joints,  and  the  skin. 
The  microbes  of  diphtheria  are  usually  limited  to  the  mucous 
membrane  of  the  upper  air  passages,  those  of  pneumonia  multiply 
in  the  lungs,  those  of  cholera,  enteric  fever,  dysentery,  and  epidemic 
diarrhoea  in  the   bowels.     The  microbes  of  tetanus  are  limited 
to  the  small  area  surrounding  the  wound  by  which  they  have 
gained  entrance. 

384.  Though  the  area  of  body  invaded  by  the  microbes  of  a 
disease  may  be  very  small,  yet  in  many  cases  the  sufferer  becomes 
extremely  ill.     Thus  in  tetanus  he  is   thrown  into  convulsions, 
which  resemble  those  produced  by  strychnine,  and  which  indicate 
that  his  spinal  column  is  in  some  way  poisoned.     We  may  search 
the  cord  in  vain  for  bacilli.     Again,  it  is  possible  to  grow  several 
species  of  pathogenic  microbes  in  broth  or  other  nutrient  fluid 
outside  the  body.     If  this  medium  is  filtered  so  that  it  is  entirely 
free  from  living  organisms,  and  then  injected  into  the  body,  the 
symptoms  of  the  disease  may  follow.     It  is  evident,  therefore,  that 
at  least  some  species  of  microbes  elaborate  poisons,  or  toxins  as 
they  are  technically  termed,  which  they  set  free  in  the  medium 
surrounding  them.     In  tetanus  and  diphtheria  the  toxins  enter  the 
blood   stream   at   the   small   area   affected,    and   so  produce  the 
symptoms  of  poisoning.     Toxins,  like  pepsin  and  trypsin,  which 
are  digestive  secretions  from  the  cells  of  the  alimentary  tract  of 
the  higher  animals,  are  evidently  ferments;   that   is,  substances 
which  in  some  unknown  way  bring  about  chemical   changes  in 
certain    other   substances   when   the  latter  are  exposed   to  their 
action. 

385.  The  cells  of  the  multicellular  organisms  are  specialized 


PHAGOCYTES  231 

for  the  performance  of  various  functions  that  adapt  the  individual 
to  his  environment.  The  function  of  certain  classes  of  cells  is 
secretion.  Thus  the  cells  of  the  alimentary  tract  secrete  the 
digestive  ferments  which  prepare  the  food  for  assimilation,  while 
such  glands  as  the  thyroid  and  the  super-renal  capsules  manufac- 
ture '  internal '  secretions  which  pass  into  the  blood,  and  are 
essential  to  the  well-being  of  the  cell-community.  Very  important 
members  of  the  cell-community  are  certain  colourless  cells,  the 
white  blood  corpuscles  or  leucocytes,  which  float  in  the  blood 
stream  or  wander  in  the  tissue  spaces.  In  a  sense  not  altogether 
metaphorical,  these  cells  are  the  sanitary  inspectors,  the  police,  the 
scavengers  of  the  community.  They  may  be  seen  to  approach 
intrusive  microbes,  enclose  them  within  their  own  substance,  and 
destroy  them,  apparently  by  digestion,  or  else  perish  themselves, 
apparently  by  poisoning.  On  account  of  this  function  of  ingesting 
microbes  they  have  been  termed  phagocytes. 

386.  The  fluid  part  of  the  blood    as   distinguished  from  the 
corpuscles   is   termed   serum.      Several    species   of  microbes,  for 
example  those  of  diphtheria,  flourish  in  serum  which  has  been 
withdrawn  from  the  body  and  freed  from  blood-cells.     It  is,  there- 
fore,  for  them    a   nutritive,    not   a  poisonous  substance.     But   if 
microbes   are  introduced  into  the   body  enclosed  in  a  capillary 
glass  tube,  the  ends  of  which  are  plugged  by  a  substance  that 
permits  the  free  diffusion  of  fluids,  but  prevents  the  escape  of  the 
micro-organisms  or  the   entrance   of  the  phagocytes,   the  latter 
collect  about  the  tube  in  numbers,  especially  at  the  open  ends 
where  they  form  clusters.     Presumably,  as  sanitary  officials,  they 
are  attracted  by  the  secretions  (toxins)  of  the  microbes.     Presently 
the  micro-organisms  perish  and  disintegrate,  apparently  in  much 
the  same  way  as  when  actually  enclosed  in  the  substance  of  the 
phagocytes.     Similarly  during  recovery  from  diphtheria  the  bacilli 
may  be  found  perishing  on  the  surface  of  the  throat,  even  when  not 
in  contact  with  phagocytes.    It  appears,  then,  that  the  phagocytes, 
and  possibly  other  cells  of  the  body,  secrete  substances,  as  harmless 
to  themselves  as  pepsin  to  the  stomach  cells,  which  act  as  counter- 
toxins  and  poison  the  microbes,  and  that  they  are  stimulated  to 
this  act  by  the  presence  of  the  microbes  and  their  toxins.     Pre- 
sumably these  counter-toxins  are  identical  with  or  similar  to  the 
digestive  ferments  that  destroy  bacilli  which  are  actually  ingested 
by  the  phagocytes. 

387.  The  toxins  of  the  various  species  of  microbes  are  not 
identical,  as   is  proved  by  the   fact   that   the   symptoms   of  the 


232  HUMAN  DISEASES 

different  diseases  are  unlike  ;  for  example,  the  symptoms  of  the 
poisoning  occasioned  by  diphtheria  are  different  in  type  from 
those  which  occur  in  tetanus.  Judging  again  by  the  symptoms, 
the  virulence  of  the  toxins  of  some  diseases  is  much  greater  than 
that  of  others.  Possibly  there  is  not  in  nature  a  more  deadly 
poison  than  the  tetanus  toxin.  The  microbes,  few  in  number  and 
located  in  a  single  small  area,  can  produce  only  an  exceedingly 
minute  quantity,  yet  the  sufferer  is  thrown  into  violent  convulsions, 
and  is  often  killed.  On  the  other  hand,  even  when  large  areas  of 
the  body  are  affected  by  leprosy,  the  person  afflicted  feels  compara- 
tively well.  In  measles,  smallpox,  influenza,  and  the  other  acute 
diseases,  the  infected  person  falls  suddenly  and  violently  ill. 
Evidently  he  is  suffering  from  intense  poisoning  ;  but  he  may  be  in- 
fected for  months  by  tuberculosis  before  he  is  even  aware  of  illness  ; 
and,  even  when  he  is  dying,  his  symptoms  are  traceable  to  nutritive 
changes,  and  to  the  irritation  and  destruction  of  tissues  caused  by 
the  microbes  themselves,  or  to  toxins  and  waste  products  produced 
by  the  microbes  of  normally  saprophytic  species,  which  have 
established  themselves  in  the  perishing  areas  of  tissue,  rather 
than  to  toxins  secreted  into  the  surrounding  medium  by  the  bacilli 
tuberculosis.  Therefore,  we  may  reasonably  infer  that,  whereas 
some  species  of  microbes  produce  virulent  toxins  which  pass  into 
the  surrounding  medium,  the  toxins  of  others  are  weak  or  are 
retained  within  the  microbes. 

388.  This  hypothesis   is    confirmed  by  another  set    of   facts 
In  acute  diseases,  such  as   diphtheria  and   tetanus,  though   the 
phagocytes  crowd  towards  the  infected  area  till  the  red  and  in- 
flamed tissue  surrounding  it  is  full  of  them,  yet,  killed  or  paralysed 
by  the  concentrated  toxins,  they  do  not  ingest  the  microbes,  at 
any  rate  at  first.    If  the  sufferer  dies  they  are  unable  to  the  end  to 
cope  with  the  invaders  ;   but  in  cases  of  recovery  they  gradually 
gain  the  upper  hand,  and  in  the  later  stages  of  disease  the  dis- 
integrating microbes  may  be  seen  within  them.      On  the   other 
hand,  in  such  diseases  as  tuberculosis  and  leprosy,  the  phagocytes 
ingest  the  microbes  from  the  first.     The  struggle  is  then,  in  a  way, 
physical,  not  one  conducted  at  long  range  like  that  fought  out  with 
the  microbes  that  produce  virulent  toxins.     Victory  depends,  so  to 
speak,  on  personal  prowess.     If  the  microbes  are  victorious,  they 
spread    and   multiply,  and    the   sufferer   eventually   dies ;    if  the 
phagocytes  are  victorious,  the  microbes  are  exterminated  and  the 
sufferer  recovers. 

389.  Microbic  diseases  differ  greatly  in  the  suddenness  of  their 


ACUTE  AND  CHRONIC  DISEASES  233 

onset,  and  in  their  duration.  As  a  rule,  the  more  sudden  and  violent 
the  onset  of  a  disease  the  shorter  is  its  duration.  Thus  influenza, 
common  cold,  pneumonia,  diphtheria,  smallpox,  and  many  others, 
develop  and  end  quickly.  After  an  illness  of  a  few  days  the  sufferer 
dies  or  recovers — at  least  he  recovers  from  the  actual  disease,  though 
injuries  (sequelae)  inflicted  by  it  may  persist,  for  example  deafness 
from  scarlet  fever.  Before  his  illness  he  is  free  from  microbes,  as 
is  proved  by  the  fact  that  he  does  not  infect  his  fellows  ;  during  it 
he  swarms  with  them,  for  he  is  then  very  liable  to  convey  infection  ; 
after  recovery,  since  he  is  no  longer  infective,  he  is  free  from  them 
again.  Something  has  banished  the  microbes.  His  body  has 
undergone  a  profound  and  remarkable  change.  From  being  a  soil 
in  which  the  parasites  were  able  to  flourish  and  multiply,  it  has  be- 
come impossible  as  an  abiding-place  to  them.  He  has  acquired 
immunity.  He  has  developed,  not  under  the  stimulus  of  nutriment, 
but  under  that  of  experience  (use).  This  kind  of  immunity,  which 
follows  recovery  from  disease,  is  obviously  quite  distinct  from  that 
power  of  resisting  infection  which  develops  under  the  stimulus  of 
nutriment,  and  is  termed  inborn  immunity,  and  is  often  seen  in 
Englishmen,  for  example  in  relation  to  tuberculosis.  In  the  case 
of  some  diseases,  smallpox,  measles  and  others,  acquired  immunity 
is  usually  permanent,  but  in  the  case  of  others,  for  example  common 
cold,  influenza,  and  diphtheria,  it  is  generally  temporary. 

390.  In  strong  contrast  to  the  acute  diseases  are  such  chronic 
maladies  as  tuberculosis  and  leprosy.  Here  the  onset  of  illness 
is  marked  by  no  sudden  symptoms  of  deep  poisoning ;  the  complaint 
pursues  a  prolonged  indefinite  course ;  recovery,  if  it  occurs,  is  as 
gradual  as  the  onset,  and  is  commonly  accompanied  by  exacerba- 
tions and  remissions  of  disease.  The  microbes  are  banished,  not 
because  that  particular  bodily  change  which  is  termed  '  acquired 
immunity'  supervenes,  but  because  an  improvement  in  general 
health,  due  to  better  nutrition,  or  surroundings,  or  some  such  cause, 
strengthens  the  individual,  and  with  him  his  phagocytes,  and  enables 
them  to  destroy  their  enemies.  Often,  in  spite  of  apparent  recovery, 
the  microbes  may  linger  in  the  system  for  years ;  and  if  the  health 
be  lowered,  the  disease,  uninfluenced  by  the  past  experience  of  the 
individual,  may  be  started  afresh  by  surviving  microbes,  or  by  a 
secondary  infection  from  without,  and  so  ultimately  prove  fatal. 
Recovery  from  such  chronic  maladies  of  indefinite  length,  there- 
fore, is  precarious  ;  it  affords  no  protection,  no  increase  of  resisting 
power,  no  ( acquired  immunity.'  Unlike  a  man  who  has  recovered 
from  smallpox,  one  who  has  experienced  tuberculosis  is  always  in 


234  HUMAN  DISEASES 

peril — in  deadly  peril,  if  exposed  to  reinfection  under  unfortunate 
conditions.  The  fact  that  he  has  experienced  the  disease  is  evi- 
dence that  he  is  susceptible  to  it,  not  that  he  has  acquired  increased 
resisting  power. 

391.  Between  such  diseases   as  smallpox  which  run  a  short, 
sharp,  definite  course   during  which   acute  poisoning  occurs,  and 
such    maladies   as    tuberculosis   which    are    unmarked   by    acute 
poisoning,  and  run  a  course  of  quite  uncertain  but  always  relatively 
prolonged    duration,    lie   such    complaints    as   enteric    fever   and 
syphilis.      The   onset,    course,   and    recovery    from    enteric    fever, 
unlike  that  from  smallpox,  is  comparatively  slow,  but  not  so  slow 
as  in  the  case  of  tuberculosis  ;  nevertheless,  there  are  very  distinct 
symptoms  of  poisoning,  and  the  duration  of  the  disease  is  pretty 
definite.     In  syphilis,  the  onset  of  the  disease  is  even  more  delayed, 
the  symptoms  of  systemic  poisoning  as  indicated  by  fever  and  a 
feeling  of  illness  are,  as  a  rule,  hardly  observable,1  and  the  microbes 
may  persist  in  the  system  for  two  or  more  years.     Nevertheless,  the 
disease  ultimately  confers  an  immunity  which  is  usually  permanent. 

392.  Malaria   occupies   a    curious    position.       Its    toxins    are 
abundant  and  virulent,  and  the  reaction  to  them    is  sharp  and 
rapid.     The  individual  develops  high  fever  and  other  symptoms 
of  poisoning ;  but  presently  the  symptoms  abate  ;  apparently  the 
microbes    cease    to   produce   toxins ;    the   individual    appears  to 
acquire  immunity.     But  this  phase  is  of  very  short  duration.     After 
an  interval,  which  may  be  measured  by  hours  or  days,  the  signs 
of  poisoning  recur.     During  the  period  of  intermission  the  microbes 
seem  in  a  resting  stage,  when,  like  the  tubercle  bacilli,  they  are 
highly  resistant  to  the  phagocytes.     In  individuals  belonging  to 
races    which  have  had  much  experience  of  malaria  a  more  per- 
manent immunity  slowly  arises.      Thus  all,  or  nearly  all,  negro 
children  on  the  West  coast  of  Africa  suffer  long  from  malaria,  and 
many  perish  of  it,  but  the  adults  are  more  or  less  free  of  it.     At 
any  rate,  they  are  much  more  resistant.     Blacks  from  the  American 
Islands,  many  of  whom  enter   the  country  as   soldiers  in  West 
India  regiments,  suffer  severely,  and  it  may  be  fatally  at  first,  a  fact 
which  has  led  Koch  and  others  to  the  highly  erroneous  conclusion 
that  no  race  is  more  resistant  than  any  other  to  malaria.      But 
West  Indian  blacks,    comparatively  few   of  whom    perish,  suffer 
much  less  than  the  white  officers.     If  they  survive  for  some  months 

1  In  syphilis  the  development  of  the  rash  is  sometimes  marked,  as  in  measles, 
by  a  rise  of  temperature  indicative  of  poisoning.  Indeed,  the  evidence  of  the 
presence  of  toxins  in  syphilis  is  clear.  See  §§  416-418. 


IMMUNITY  235 

they  acquire  immunity ;  whereas  the  whites  continue  to  suffer — 
if  anything  more  and  more  severely  as  they  become  weakened- 
The  latter  cannot  acquire  permanent  immunity.  They  cannot 
rear  families,  and  a  white  settlement  in  African  swamps  or  forests 
would  soon  become  as  extinct  as  the  British  colony  in  Darien. 
The  following  from  Miss  Mary  Kingsley  is  very  much  to  the 
point : — 

393.  "  Yet  remember,  before  you  elect  to  cast  your  lot  with  the 
West  Coasters,  that  85  per  cent,  of  them  die  of  fever,  or  return 
home  with  their  health  permanently  wrecked.      Also  remember 
that  there  is  no  getting  acclimatized  to  the  Coast.     There  are,  it 
is  true,  a  few  men  out  there,  who,  although  they  have  been  resident 
in  West  Africa  for  years,  have  never  had  fever,  but  you  'can  count 
them   on  the  fingers   of  one  hand.     There   is  another  class  who 
have  been  out  twelve  months  at  a  time,  and  have  not  had  a  touch 
of  fever ;  these  you  want  the  fingers  of  your  two  hands  to  count, 
but  no  more.     By  far  the  largest  class  is  the  third,  which  is  made 
up  of  those  who  have  had  a  slight  dose  of  fever  once  a  fortnight, 
and  some  day,  apparently  for  no  extra  reason,  get  a  heavy  dose, 
and  die  of  it.     A  very  considerable  class  is  the  fourth — those  who 
die  within  a  month  or  a  fortnight  of  going  ashore. 

"  The  fate  of  a  man  depends  solely  on  his  power  of  resisting 
the  so-called  malaria,  not  in  his  system  becoming  immuned  to  it. 
The  first  class  of  men  I  have  cited  have  some  unknown  element  in 
their  constitutions  that  renders  them  immune.  With  the  second 
class  the  power  of  resistance  is  great,  and  can  be  renewed  from  time 
to  time  by  a  spell  home  in  a  European  climate.  In  the  third 
class  the  state  is  that  of  cumulative  poisoning ;  in  the  fourth  of 
acute  poisoning."  x 

394.  Now  since  acquired  immunity  arises  most  rapidly  in  acute 
diseases  in  which  virulent  toxins  are  most  abundantly  and  quickly 
produced,  since  it  arises  slowly  when  toxins  are  less  abundant  or 
more  gradually  developed,    and    since  it  never  arises   when   the 
evidence  indicates  that  poisoning  by  toxins  plays  a  minor  part  or 
no  part  at  all  in  the  disease,  it  is  clear  that  acquired  immunity  is 
due  directly  to  the  presence  of  the  toxins,  not  to  the  presence  of 
the   microbes.      This   hypothesis   is   confirmed   by  the   fact  just 
mentioned,   that  in   acute  diseases   the    phagocytes   are  able   to 
approach  and  destroy  the  microbes  as  soon  as  the  symptoms  ot 
acute   poisoning   are    mitigated,   whereas    in    the   more    chronic 
maladies,  though  from  the   first  undeterred   by   toxins,  they  are 

1  Travels  in  West  Africa,  pp.  526-7.     Macmillan  &  Co. 


236  HUMAN  DISEASES 

unable  to  overcome  the  microbes  except  after  a  prolonged  struggle 
from  which  no  acquired  immunity  results. 

395.  It  is  a  noticeable  and  very  important  fact  that  immunity 
acquired    against   any   acute   disease  does   not   confer   immunity 
against  any  other.      Thus  experience  of  smallpox  or  scarlatina 
affords  no  protection  against  measles  and  whooping-cough.     The 
toxins   differ,   and  therefore  immunity  to  each   disease  must  be 
acquired  separately. 

396.  Obviously,  the  various   species  of  microbes  are  adapted 
by  different  means  to  the  environment.     In  the  search  for  nutri- 
ment they  enter  the  body  in  different  ways.     Some  species  defend 
themselves  from  the  phagocytes  by  means  of  toxins  which  they 
secrete  into  the  surrounding  medium  ;  others  have  evolved  great 
powers  of  resistance  which  doubtless  depend  in  part  at  least  on 
toxins  retained  within  themselves.     In  no  case  is  the  death  of  the 
host  they  inhabit  of  advantage  to  the  microbes.     They  are  adapted 
for  the  temperature,  nutriment,  and  other  conditions  met  in  the 
living  body.     The  dead  body  becomes  the  prey  of  the  bacteria  of 
putrefaction.      The  death   of  the  individual,  the   cell-community 
attacked  by  them,  is  comparable  to  the  destruction  of  a  hive  by 
the  bee-keeper  in  an  attempt  to  secure  the  honey.      Continued 
multiplication  of  the  microbes  within  the  system,  however,  insures 
the  death  of  the  host,  if  only  by  interference  with  the  functions  of 
life.     The  preservation  of  their  species,  therefore,  demands  that 
the  microbes  shall  pass  through  an  unending  succession  of  living 
individuals.     In  acute  diseases  this  is  secured  by  rapid  multiplica- 
tion and   migration  to  fresh  and  susceptible  persons  during  the 
short  interval  of  safety  afforded  by  the   toxins  before   acquired 
immunity  or  death  supervenes.     In  the  more  chronic  maladies  there 
is  less  need  for  rapid  multiplication  and  migration.     The  host  is 
not  poisoned.     His  continued  existence  is  an  advantage  as  afford- 
ing a  continuous  supply  of  nutriment  and  prolonged  opportunities 
for  infecting  other  individuals.     However  quickly  the  microbes  may 
multiply,  they  never  increase  at  the  tremendously  rapid  rate  which 
characterizes  the  organisms  of  the  acute  diseases.     Thus,  in  a  few 
days  or  weeks,  measles,  influenza,  or  smallpox  may  spread  over 
a  vast  area  of  country,  and  infect  millions  of  people.     The  progress 
of  tuberculosis  and  leprosy  is  always  much  slower. 


CHAPTER   XII 

ACQUIRED  IMMUNITY 

Intra-  and  extra-cellular  toxins — Susceptibility  to  disease — Methods  of  altering 
virulence — Parasites  and  saprophytes — Smallpox — Rabies — Anthrax — Diptheria 
— Active  and  passive  immunity — Antitoxin — Syphilis — Snake  venom,  and 
vegetable  poisons — Yeast — The  nature  of  acquired  immunity — Pasteur's  theory — 
Chauveau's  theory — The  theory  of  neutralization — The  theory  of  habituation — 
Ehrlich's  side-chain  theory — Inborn  and  acquired  immunity. 


T 


397.  f  |  "\HE  nature  of  acquired  immunity  and  the  means  by 
which  it  is  acquired  have  long  been  subjects  of  debate. 
Many  hypotheses  have  been  formulated.  Since  the 
mass  of  facts  is  enormous,  and  the  difficulty  of  tracking  their 
relations  very  great,  the  subject  is  an  exceedingly  difficult  and 
complex  one.  Probably  a  workable  idea  of  it  will  be  most  easily 
conveyed  to  the  reader  if  we  begin  by  setting  down  an  array  of 
facts,  all  of  which  I  believe  have  been  verified  ;  or,  at  any  rate,  few, 
if  any,  of  which  are  disputed. 

398.  (a)  Acquired  immunity  is  evidently  a  reaction  against  toxins. 
The  toxins  of  the  acute  and  sub-acute  diseases,  against  which 
alone  immunity  is  acquired,  are  set  free  in  the  medium  surrounding 
the  microbes  much  as  snake  venom  is  set  free  in  the  blood-stream 
of  the  victim.  Other  toxins,  zVz/ra-cellular  toxins,  are  more  or  less 
retained  within  the  microbes.  Thus,  if  the  bacilli  of  tuberculosis, 
the  extra-cellular  poisons  of  which  are  non-existent  or  very 
feeble,  be  triturated  in  a  mortar  and  treated  with  water,  a  poison, 
tuberculin,  may  be  obtained,  which,  when  injected,  produces 
symptoms  markedly  different  from  those  which  occur  in  the  actual 
disease.  (£)  Some  species  of  microbes  can  be  cultivated  in  blood- 
serum  outside  the  body — not  only  in  the  serum  of  susceptible 
individuals,  but  also  in  the  serum  of  those  who  have  acquired 
immunity,  (c)  Immunity  is  influenced  by  individual  peculiarity, 
race,  and  age.  Thus  many  Englishmen  are  under  ordinary  con- 
ditions immune  to  tuberculosis;  "white  rats,  adult  dogs,  many 
kinds  of  birds,  and  frogs  are  naturally  immune  to  the  bacillus  of 
anthrax,  which  is  very  fatal  to  cattle,  common  rats,  field-mice, 

237 


238  ACQUIRED  IMMUNITY 

and  man.  Algerian  sheep  resist  the  organism,  whereas  other 
breeds  of  sheep  readily  succumb.  Dogs  are  practically  immune 
to  tuberculosis,  while  guinea-pigs  are  killed  by  the  most  minute 
dose  of  the  bacillus.  Rats  and  mice  are  not  susceptible  to  diph- 
theria. In  none  of  these  cases,  however,  is  the  immunity  absolute. 
By  altering  the  circumstances  of  the  animal  it  is  generally  possible 
to  render  it  susceptible  to  the  disease.  Thus,  by  keeping  frogs  at 
a  raised  temperature,  it  is  possible  to  infect  them  with  anthrax  ;  and 
by  overtiring  animals  by  excessive  work  they  maybe  made  suscep- 
tible to  infection  with  organisms  to  which  they  otherwise  possess 
almost  complete  immunity."  x 

399.  (cT)  As  a  general  rule  parasites  flourish  best  in  the  species  of 
animal  which  they  normally  inhabit,  doubtless  because  they  have 
evolved  adaptation   to  that   particular   habitat ;    for   this   reason 
human  diseases  more  readily  afflict  allied  species  (mammals  in 
general  and  monkeys  in  particular)  than  types  less  akin,     (e)  Mic- 
robic   species,  if  removed   from   their   normal   habitat  (e.g.  from 
one  species  of  animal  to  another,  or  from  the  living  body  to  non- 
living media),  are  apt  to  alter  their  degree  of  virulence.      The 
longer  they  inhabit  a  species  of  animal  the  more  virulent,  as  a 
rule,  do   they  grow   for   that   species    till   a  degree  of  virulence, 
sufficient  to  enable  the  microbes  to  persist,  is  reached.      Thus  the 
microbes  of  rabies  taken  from  dogs  and  passed  through  a  series  of 
rabbits  have  their  virulence  immensely  exalted  for  rabbits,  though 
it  is  said  to  be  lessened  for  human  beings.2     When  transferred  to 
non-living  media  microbes  tend  to  lose  their  virulence  and  become 
saprophytes.     The  only  rational  explanation  appears  to  be  that 
in  the  former  case  selection  of  the  microbes  that  are  most  virulent 
to  the  new  type  of  host,  and  therefore  best  able  to  defend  them- 
selves from  his  phagocytes,  causes  progression ;    whereas  in  the 
latter  cessation  of  selection  leads  to  the  loss  of  the  now  useless 
virulence.     On  the  other  hand,  normally  saprophytic   organisms 
may  be  rendered  virulent  by  placing  them  in  the  living  body,  first 
in  situations  where  they  are  least  exposed  to  the  phagocytes,  and 
then  in  situations  where  they  are  more  exposed.    Some  organisms, 
normally  saprophytic  (e.g.  the  tetanus  bacilli  and  those  which  cause 
putrefaction)  are  intensely  poisonous.     Apparently    their    toxins 
have  been  evolved,  not  through  a  struggle  with  phagocytes,  but 
probably  with  other  lowly  organisms. 

400.  (/)  It  has  been  conclusively  proved  experimentally  that  if 
smallpox  be  passed  through  a  series  of  calves  it  becomes  cowpox ; 

1  Bosanquet,  Serums,  Vaccines  and  Toxines,  p.  13.  2  Op.  cit.,  p.  153. 


SMALLPOX  239 

in  the  horse  it  becomes  horse-pox ;  transferred  back  to  man 
it  is  vaccinia.  By  then  the  nature  of  the  microbes  has  been 
profoundly  altered.  Owing  probably  to  a  loss  of  virulence 
(i.e.  offensive  and  defensive  power),  they  are  unable  to  spread  over 
the  body,  but  are  restricted  to  the  spot  of  inoculation,  where  they 
and  their  toxins  are  most  concentrated.  The  toxins,  however, 
permeate  the  body,  and  induce  a  general  change,  from  which 
results  recovery  from  vaccinia  and  immunity  to  smallpox.  The 
absence  of  the  microbes  from  the  blood-serum,  and  therefore  from 
the  lungs,  prevents  their  diffusion  by  the  breath.  Probably  it  is 
for  this  reason  that  vaccinia,  unlike  smallpox,  is  not  air-borne. 
Consequently,  it  does  not  infect  people  in  the  vicinity.  It  has 
become  like  rabies  and  syphilis,  a  disease  which  is  communicated 
only  by  direct  contact  and  under  particular  circumstances.1  It 
does  not,  during  its  passage  through  a  series  of  human  hosts,  again 
evolve  the  ancient  characteristics  of  smallpox  because,  on  the  one 
hand,  the  failure  of  its  microbes  to  pass  naturally  from  a  sufferer 
to  his  fellows  results  in  the  extermination  of  all  that  are  not 
artificially  removed,  so  that  there  is  no  survival  of  the  fittest  as  re- 
gards the  power  to  migrate,  while,  on  the  other  hand,  man  artificially 
enables  the  more  and  the  less  fit  to  migrate  alike.  Human  races 
which  have  had  no  ancestral  experience  of  smallpox,  which  have 
not  been  weeded  out  by  it,  have  comparatively  low  powers  of 
resistance.  A  party  of  Esquimaux,  who  visited  Berlin  and  were 
vaccinated  there,  developed  a  general  disease  resembling  or  identi- 
cal with  smallpox,  and  perished  of  it.2  The  microbes,  therefore, 
were  able  to  spread  over  the  entire  body.  Doubtless  if  vaccinia 
were  passed  through  a  series  of  such  people,  and  then  through 
more  resistant  types,  it  would  again  become  smallpox — just  as 
harmless  saprophytic  organisms  become  virulent  parasites  if  passed, 
under  favourable  circumstances,  through  a  series  of  living  hosts. 

401.  (g)  Rabies  in  dogs  is  a  very  deadly  disease.  If  passed 
through  a  series  of  rabbits,  it  becomes  still  more  virulent,  at  any  rate, 
for  rabbits.  If  passed  through  a  series  of  monkeys  it  becomes  milder. 
Pasteur  secured  complete  immunity  from  virulent  rabies  by  inocu- 
lation first  with  the  mildest  type  (from  monkeys),  then  with 
more  virulent  types,  and  lastly,  with  the  most  virulent  type  (from 
rabbits).  Subsequently  he  discovered  an  even  better  method,  that 

1  Not  all  '  general '  diseases,  malaria  for  example,  are  air-borne.     To  be  air- 
borne it  is  necessary  not  only  that  the  microbes  shall  find  their  way  to  the  air 
passages,  but  also  that  they  shall  be  adapted  for  transmission  through  the  air. 

2  The  Scottish  Medical  and  Surgical  Journal,  April  1900,  p.  330. 


240  ACQUIRED  IMMUNITY 

now  in  use.  Rabies  develops  slowly  in  an  infected  person.  The 
microbes  inhabit  especially  the  great  nervous  centres,  the  brain  and 
spinal  cord.  Pasteur  dried  a  series  of  cords  from  infected  rabbits, 
made  emulsions  from  them,-  and  injected  the  emulsions  into  in- 
dividuals who  had  acquired  the  disease,  but  had  not  as  yet 
developed  the  symptoms.  He  began  with  a  cord  which  had  been 
artificially  dried  for  fourteen  days.  Next  he  used  in  succession 
fresher  cords,  till  he  injected  material  from  one  which  was  abso- 
lutely fresh,  and  which  would  have  infallibly  communicated  the 
disease  had  the  previous  treatment  not  been  undergone.  As  a 
result  the  individual,  so  far  from  acquiring  the  disease,  developed 
immunity. 

402.  (h)  Pasteur  subjected  the  bacilli  of  anthrax,  for  a  longer 
or  shorter  time,  to  an  abnormal  degree  of  heat.     He  found  they 
became  ' attenuated'  (i.e.  lost  their  virulence)  in  proportion.      If, 
now,  sheep  were  inoculated,  first  with  bacilli  of  little  virulence, 
and  then  in  succession  with  those  of  greater  virulence,  they  could 
eventually  be  rendered  immune  to  those  of  the  greatest  virulence. 
Attempts  to  pass  directly  from  weak  to  strong  bacilli  led  to  the 
death  of  the  infected  sheep,     (i)  A  few  microbes  are  not,  as  a  rule, 
sufficient  to  infect  even  a  very  susceptible  individual.     They  are 
destroyed  by  the  phagocytes,  and  tend  merely  to  induce  an  in- 
crease of  resisting  power.     Rabbits  are  susceptible  to  anthrax,  and 
young  animals  more  susceptible  than  older  individuals.     It  has 
been  found  that  not  less  than  16,000  bacilli  must  be  injected  into 
a  young  rabbit  to  induce  the  disease. 

403.  (/)  If  diphtheria  bacilli  be  cultivated  in  broth,  outside  the 
body,  they  render  the  broth  intensely  poisonous  with  their  toxins. 
If  the  broth  be  injected,  at  first  in  small  but  afterwards  in  larger 
doses,  into  a  horse,  the  animal  acquires  immunity,  and  remains  in 
good  health  during  the  rest  of  the  treatment.     But  immediately 
after  a  large  dose  his  blood-serum  is  poisonous  to  other  animals 
which  have  not  been  similarly  treated.     If,  however,  the  serum  be 
withdrawn  from  him  after  a  fit  period,  it  is  not  only  harmless,  but 
helps  another  animal  (e.g.  man),  who  is  suffering  from  the  actual 
disease,  to  recover ;  or,  if  not  suffering,  it  renders  him,  for  a  time 
at  least,  insusceptible.     This  is  the  celebrated  antitoxin  treatment 
which  has  greatly  reduced  the  mortality  from  diphtheria,  and  is 
yearly  being  extended  to  other  diseases,  the  medical  treatment  of 
which  was  formerly  of  little  value.     (/£)  Roux  found  it  possible  to 
obtain  at  different  times  two  lots  of  serum  of  equal  value  from  a 
prepared  horse,  though  no  intermediate   injection  of  toxin  had 


ACTIVE  AND  PASSIVE  IMMUNITY  241 

been  made.  (/)  An  injection  of  a  right  quantity  of  antitoxin 
confers  a  '  passive '  immunity  which  is  less  enduring  than  the 
'active'  immunity  which  results  from  actual  experience  of  the 
disease.  Some  authorities  suppose  that  the  former  is  due  merely 
to  the  presence  of  neutralizing  substances  introduced  with  the 
injection  of  antitoxin,  or  afterwards  produced  under  its  influence 
by  the  individual,  and  that  it  persists  only  so  long  as  these  remain 
within  the  system  ;  whereas  active  immunity  is  thought  to  be  a 
vital  reaction  to  the  microbes  themselves.  But  probably  the  truth 
is,  that  active  and  passive  immunity  are  merely  degrees  of  the 
same  thing,  and  that  in  any  disease  the  duration  of  immunity 
depends  more  on  the  severity  of  the  illness,  and  on  the  consequent 
completeness  of  the  reaction,  than  on  the  presence  or  absence  of 
the  microbes.  A  kind  of  passive  immunity  may  be  induced  by 
the  repeated  injection  of  small  quantities  of  microbes.  Workmen 
in  sewers  acquire  a  passive  immunity  to  enteric  fever,  doubtless 
through  constant  experience  of  small  doses  of  bacilli.  Dwellers  in 
malarious  countries,  or  in  places  where  yellow  fever  is  prevalent, 
live  immune  till  after  a  sojourn  in  a  more  healthy  climate.  One 
vaccination  mark  confers  an  immunity  which  is  more  passive  than 
that  conferred  by  two,  that  conferred  by  two  is  less  enduring  than 
that  conferred  by  more,  and  still  less  lasting  than  that  acquired 
through  experience  of  actual  smallpox.  Judged  by  its  duration, 
immunity  against  such  diseases  as  diphtheria,  influenza,  and 
common  cold  is  always  passive. 

404.  (m)  Just  as  immunity  acquired  against  any  disease  does  not 
confer  immunity  against  any  other,  just  as  vaccinia  confers  im- 
munity only  against  smallpox,  so  the  antitoxin  of  any  one  disease 
confers  no  resisting  power  against  any  other,  (n)  Within  limits,  a 
dose  of  toxin  large  enough  to  be  poisonous  may  be  rendered 
harmless  by  previous  intermixture  with  the  corresponding  anti- 
toxin. This  '  neutralization '  is  somewhat  less  marked  if  the  two 
be  simultaneously  injected  into  separate  parts  of  the  body,  and 
still  less  marked  if  the  antitoxin  be  injected  some  time  after  the 
toxin — which,  in  effect,  is  what  is  done  when  disease  is  treated  by 
means  of  appropriate  serum.  A  mixture  of  toxin  and  antitoxin, 
for  example  that  of  tetanus,  in  a  proportion  just  harmless  to  a 
rather  resistant  animal  of  a  susceptible  species,  for  example  a 
mouse,  is  poisonous  to  a  more  susceptible  animal  of  the  same 
species,  or  to  an  animal  of  a  more  susceptible  species,  for  example 
a  guinea  pig.  An  animal  which  has  acquired  immunity  to  a 
disease  (i.e.  which  has  acquired  the  power  of  resisting  infection) 
16 


242  ACQUIRED  IMMUNITY 

does  not  necessarily  retain  its  power  of  tolerating  large  doses  of 
toxin  when  these  are  injected. 

405.  (o)  Syphilis  is  a  disease  of  such  long  duration  that  it  may 
cover  several  pregnancies  in  a  woman.     As  a  rule,  the  infants  that 
are  born  during  her  illness  suffer  less  and  less  as  the  disease  pro- 
gresses.    Thus,  speaking  generally,  if  she  have  rapidly  recurring 
pregnancies,  at  first  she  miscarries  early  in  the  pregnancy,  then  a 
dead  but  fully  developed  child  is  born,  then  a  child  which  appears 
healthy,  but  soon  wastes  and  dies,  then  one  who  survives  but  ex- 
hibits signs  of  disease,  and  lastly  one  which  shows  no  signs  of  it. 
Even  if  both  parents  be  diseased  the  successive  children  tend  to  suffer 
less  and  less.     If  a  diseased  woman  bears  children  to  successive  men, 
then,  whether  the  male  parents  be  diseased  or  not,  her  successive 
children  tend  to  suffer  less  and  less  as  time  goes  on  till  they  do  not 
suffer  at  all.     But,  if  a  diseased  man  has  infected  children  by  a  suc- 
cession of  women  who  were  not  previously  diseased,  the  last  child 
tends  to  suffer  as  severely  as  the  first.    Evidently,  then,  while  a  woman 
may  mitigate  the  disease  for  her  offspring,  a  man  cannot.     Though 
a  woman  suffering  from  the  disease  tends  to  confer  immunity  on 
her  surviving  children,  yet  a  woman  recovered  from  it  confers  none 
on  children   that   are   not   infected — at   least,  judging   from   the 
analogy  of  other  diseases,  so  we  must  suppose,  for  a  mother  who 
has  suffered  from  and  acquired  immunity  against  measles,  scarla- 
tina, smallpox,  or  any  other  malady,  confers  no  immunity  on  her 
offspring.     A  woman  who  has  recovered  from  syphilis  has  never 
been  known  to  bear  a  diseased  child  to  an  infected  father.     But  a 
woman  who  has  not,  and  never  has  had  the  disease,  may  bear  an 
infected  child  to  such  a  mate.     The  bearing  of  the  infected  child 
confers  immunity  on  her,  for  she  never  contracts  syphilis  when 
suckling  it,  though  healthy  wet  nurses  may.     A  diseased  woman 
may  bear  a  healthy  child  which,  presumably,  is  immune,  since  it 
does  not  acquire  the  disease  when  suckled  by  her.     The  proof  that 
it  is  not  infected  is  afforded  by  the  fact  that  it  does  not  convey  the 
disease  to  a  healthy  wet  nurse. 

406.  (/)  Snake  poison  (a  toxin)  may  be  swallowed  in  doses  a 
thousand  times  larger  than  would  suffice  to  cause  death  if  injected 
under  the  skin.     Immunity  instead  of  death  results.     The  Bushmen 
of  South  Africa  are  declared  on  good  authority  to  seek  and  obtain 
safety  from  snake-bite  by  swallowing  poison  glands.     Snake  venom 
artificially  attenuated  is  now  successfully  used  as  an  antitoxin  for 
the  cure  of  snake  poisoning,     (q)  Nicotine,  opium,  strychnine,  and 
other  vegetable  poisons,  many  of  which  are  used  as  medicines,  are, 


PASTEUR  AND  CHAUVEAU  243 

in  effect,  toxins — that  is,  they  are  defensive  poisons  which  have 
been  evolved  as  means  of  protection  against  animal  enemies,  insects 
or  herbivora.  Usually  such  toxins,  besides  being  poisonous,  have 
an  unpleasant  taste.  As  is  well  known,  use  enables  the  individual 
to  tolerate  immensely  increased  doses  of  some  vegetable  poisons, 
such  as  nicotine  and  opium ;  in  other  words,  a  high  degree  of 
immunity  may  be  acquired.  The  vegetable  toxins  abrin,  ricin,  and 
crotin  are  probably  of  a  proteid  nature,  resembling  the  toxins  of 
disease  in  having  a  very  complex  chemical  composition.  In  the 
case  of  each  of  them  it  is  possible  to  manufacture  an  antitoxin 
protective  against  the  corresponding  toxin,  (r)  If  the  yeast  fungus 
be  placed  in  a  solution  of  sugar  it  consumes  the  latter  and  excretes 
alcohol.  Alcohol  is  not  a  toxin,  a  defensive  weapon,  but  a  waste 
product,  comparable  to  the  urine  of  man  not  to  the  venom  of 
snakes.  When  it  attains  a  certain  strength  (about  14  per  cent.)  in 
the  solution  the  fungus  perishes — just  as  the  cells  of  a  man's  body 
perish  if  his  excreta  be  retained  as  in  kidney  or  liver  disease. 

407.  Here  we  have  a  confused  mass  of  data,  culled  from  many 
sources.     Our  task  is  to  ascertain  the  relations  of  the  facts  and  so 
link  them  together,  so  systematize  them,  as  to  discover,  if  possible, 
how  immunity  is  acquired.     Pasteur  supposed  that  each  species  of 
microbe  finds  in  the  body  of  its  host  a  special  pabulum,  the  ex- 
haustion of  which  results  in  the  starvation  of  the  microbes,  and 
therefore  in  immunity — permanent  if  the  pabulum  be  not  renewed, 
temporarily  if  it  be  renewed.     But  Nature  has  evolved  both  man 
and  microbes  as  bundles  of  adaptations.     It  would  be  strange  if 
man  possessed  a  series  of  pabula  which  are  not  necessary  to  his 
well-being — for  he  lives  very  well  after  recovery — but  which  render 
him  liable  to  disease.     Chauveau  supposed  that  the  microbes  like 
yeast,  are  killed  by  the  concentration  of  their  own  excreta,  and 
that  immunity  is  permanent  or  temporary  accordingly  as  these 
waste  products  are  permanently  bottled  up  within  the  body,  or 
eliminated.     But  waste  products  are  usually  less  inimical  to  the 
organism  producing  them  than  to  most  organisms  to  which  they 
are  strange.     Thus  yeast  fungi  are  able  to  live  in  a  solution  in 
which  the  percentage  of  alcohol  is  as  high  as  thirteen  or  fourteen  ; 
but  no  man  could  live  if  alcohol  formed  anything  like  that  propor- 
tion of  his  total  body  weight.      Both  Pasteur's  and  Chauveau's 
hypotheses  are  decisively  negatived  by  the  fact  that  microbes  may 
flourish  in  sera  taken  from  immune  individuals. 

408.  Highly  popular  is,  or  was,  the  hypothesis  that  microbes  or 
their  hosts  produce  substances  (the  antitoxins)  which  chemically 


244  ACQUIRED  IMMUNITY 

neutralize  and  render  harmless  the  toxins — much  as  an  acid 
neutralizes  a  base — and  so  enable  the  phagocytes  to  overcome 
their  enemies.  The  supporters  of  this  hypothesis  point  to  the 
suggestive  facts  that,  within  limits,  toxins  are  rendered  harmless 
to  an  animal  if  the  corresponding  antitoxins  are  first  injected  in 
sufficient  quantities,  and  that,  if  mixed  with  the  antitoxins  before 
injection,  they  are  neutralized  more  thoroughly,  and  therefore  are 
less  poisonous  than  when  injected  simultaneously  but  separately, 
and,  further,  that  when  mixed  outside  the  host  a  definite  amount  of 
antitoxin  will  render  inert  a  definite  amount  of  toxin.  But  a 
number  of  additional  facts  indicate  that  the  neutralization  theory 
is  untenable.  If  a  fatal  dose  of  toxin  be  rendered  harmless  by  a 
minimum  quantity  of  antitoxin,  and  then  another  lethal  dose 
of  toxin  be  added  to  the  mixture,  the  latter  should  become  lethal 
once  more.  But  it  does  not,  it  merely  causes  a  very  slight  illness. 
It  needs  the  addition  of  quite  a  number  of  lethal  doses  to  make 
the  mixture  deadly.  Again  a  mixture  of  toxin  and  antitoxin  may 
be  made  which  is  harmless  for  one  animal  (e.g.  mouse)  but 
poisonous  to  another  (e.g.  guinea  pig),  a  fact  which  proves  that  the 
reaction  that  results  in  immunity  is,  not  merely  a  chemical,  but  a 
vital  one.  Yet  again,  if  a  mixture  of  diphtheria  toxin  and  antitoxin 
which  is  harmless  to  a  mouse  be  made,  it  is  rendered  poisonous  by 
heating  it  to  the  boiling  point  of  water.  Similarly  if  the  mixture 
be  placed  in  a  porcelain  filter  the  toxin  passes  through,  but  the  anti- 
toxin remains,  a  fact  which  is  decisive  that  the  interaction  between 
the  two  substances  is  not  of  the  nature  of  a  chemical  combination. 
409.  Both  toxins  and  antitoxins  are  substances  of  highly 
complex  chemical  composition  ;  each  toxin  is  *  neutralized '  only  by 
the  corresponding  antitoxin  ;  the  power  of  producing  its  particular 
toxin  has  been  evolved  by  every  species  of  microbe  ;  but  antitoxins 
as  shown  by  the  acquirement  of  immunity  may  be  produced  by 
races  which  have  had  no  previous  experience  of  the  corresponding 
diseases  ;  antitoxins  have  been  found  in  the  blood  of  animals  a  few 
minutes  after  the  injection  of  the  corresponding  toxins.  Therefore 
the  hypothesis  of  the  chemical  neutralization  of  toxins  by  antitoxins 
elaborated  by  the  individual  attacked  involves  the  assumption  that 
the  animal  body  is  a  species  of  magic  bottle  which  instantly 
produces,  under  conditions  never  perhaps  experienced  by  the  race, 
elaborate  substances  exactly  suited  to  the  needs  of  the  moment. 
It  is,  in  fact,  a  hypothesis  of  immunization  by  miracle.  Equally 
founded  on  an  appeal  to  the  supernatural  is  the  hypothesis,  which 
is  or  was  popular,  that  the  microbes  after  producing  toxins  which 


THE  HYPOTHESIS  OF  NEUTRALIZATION         245 

defend  their  lives  are  good  enough  to  produce  antitoxins  which 
compass  their  own  destruction. 

410.  The  theory  of  neutralization,  so  simple  at  first  sight  but 
so  incredible  when  examined  closely,  is  one  that  would  naturally 
occur  to  students  of  chemistry  which  to  some  extent  all  medical 
men,  and  more  especially  all  bacteriologists  are  by  training.     A 
theory  hardly  less  obvious  and  certainly  more  probable,  is  more 
likely  to  find  favour  with  students  of  evolution  which  no  medical 
men  are  as  yet,  at  least  by  formal  training.     Men  get  *  used '  to 
opium  and  nicotine  just  as  they  get  used  to  exertion  or  heat  or 
anything  else.     Opium  and    nicotine  are  toxins  in  a  real  sense. 
No  one  has  suggested  that  the  power  of  tolerating  increased  doses 
of  them  is  due  to  the  production  of  neutralizing  substances,  any 
more  than  they  have  suggested  that  the  power  of  tolerating  heat 
or  fatigue  is  due  to  the  formation  of  substances  which  chemically 
neutralize  heat  or  fatigue.     In  each  case  the  growth  of  toleration, 
like  the  growth  of  the  limbs  after  birth,  is  plainly  one  of  that  large 
class  of  acquired  characters  by  means  of  which  the  higher  animals 
achieve  part  of  their  development  and  by  which  they  are  made  so 
adaptive.     There  does  not  seem  to  be  any  very  valid  reason  why 
we  should  place  acquired  immunity  to  disease  in  another  category 
and  ascribe  to  it  a  miraculous  origin.     Certainly,  antitoxins  seem 
to  neutralize  toxins,  but  it  is  possible  to  find  an  explanation  which 
savours  less  of  the  supernatural. 

411.  The  spinal  cord  of  a  rabbit  in  the  later  stages  of  virulent 
rabies  contains  microbes  and  their  toxins,  but,  presumably,  little  or 
no  antitoxin,  for  the  animal,  if  not   killed,    invariably   perishes. 
But,  if  we  kill  the  rabbit  and  dry  the  cord,  antitoxins  soon  begin  to 
appear.     Evidently,  moreover,  the  quantity,  or  quality,  or  both,  of 
this  substance  alters  in  a  peculiar  way  from  day  to  day ;  for,  if  we 
inject  an  emulsion  from  a  cord  of  a  freshly  killed  rabbit  into  an 
infected  man,  we  do  not  cure  his  disease.     Nor  do  we  cure  it  if 
we  make  the  emulsion  from  a  cord  which  has  been  dried  a  fort- 
night.    To  achieve  the  desired    result  we  must  follow  a  certain 
routine ;   we  must  begin  with  a  cord  that  has  been  thoroughly 
desiccated  and  then  proceed  by  fresher  and  fresher  cords  till  at 
last  we  inject  one  that  is  absolutely  fresh  and  virulent.     Here  the 
theory  of  neutralization  clearly  breaks  down.    The  cells  of  the  cord 
are  dead  and  dried  and  cannot  produce  a  neutralizing  substance  ;  the 
microbes  are  dead  or  dying  and  are  wildly  unlikely  to  produce  it ; 
most  decisive  of  all,  the  immunizing  agent  is  not  found  in  any 
particular  cord,  but  only  in  a  succession  of  cords  when  these  are  used 


246  ACQUIRED  IMMUNITY 

in  a  certain  order.  Again,  if  we  pass  smallpox  microbes  through 
a  succession  of  calves,  we  attenuate  the  disease.  Presumably,  we 
so  weaken  the  toxins  that  the  microbes  are  unable  to  spread 
through  the  body.  Vaccinia,  with  its  weakened  toxins  confers 
immunity  against  smallpox,  for,  if  a  man  has  recovered  from  the 
former,  his  phagocytes  are  able  to  destroy  the  microbes  of  the 
latter  when  brought  in  contact  with  them;  hence  his  acquired 
immunity.  In  the  same  way  it  is  possible  to  immunize  against 
rabies  by  passing  the  microbes  through  a  series  of  animals 
(monkeys)  which  'attenuate1  it.  Again  by  subjecting  anthrax 
microbes  to  an  abnormal  degree  of  heat  we  are  able  to  attenuate 
them.  By  inoculating  first  with  much  attenuated  microbes,  and 
then  in  succession  with  less  attenuated  microbes,  we  are  able  to 
bring  about  immunity  against  the  most  virulent  form  of  the 
malady.  Since  in  these  cases,  we  introduce  directly,  not  anti- 
toxins but  attenuated  microbes,  then  if  the  theory  of  chemical 
neutralization  be  correct  we  must  make  the  incredible  hypotheses 
that  the  passage  of  rabies  through  monkeys,  of  smallpox  through 
calves,  and  the  subjection  of  anthrax  to  heat  so  alters  the  microbes 
that  they  produce  substances  which  exactly  neutralize  the  toxins 
which  their  ancestors  produced. 

412.  It  is  very  significant  that  microbes,  attenuated  to  the 
right  degree,  will  confer  immunity  on  animals  of  a  species  some- 
what resistant  to  the  disease,  but  cause  death  with  symptoms  of 
the  virulent  disease  in  animals  of  a  species  that  is  less  resistant. 
A  parallel  fact  is  that,  while  smallpox,  measles  and  many  other 
diseases  destroy  the  less  resistant,  they  confer  immunity  on  the 
more  resistant  individuals  of  the  same  species.  Obviously,  there- 
fore, the  toxins  of  attenuated  disease  ^still  remain  toxins — but 
weakened  toxins.  Consequently  we  are  driven  to  the  conclusion 
that  in  rabies,  smallpox,  and  anthrax  experience  of  a  mild  variety 
of  a  disease  helps  to  the  acquirement  of  resisting  power  against 
the  more  virulent  variety — not  by  introducing  substances  which 
chemically  neutralize  the  toxins  but  by  supplying  weakened  toxins, 
reactions  against  which  act  as  stepping  stones  towards  reaction 
against  strong  toxins.1  In  other  words,  when  the  individual  has 

1  The  alteration  in  the  toxin  of  rabies  in  drying  cords  may  arise  in  one  of 
two  ways  :  (i)  the  virulent  toxin  may  be  directly  altered  by  the  drying  process, 
or  (2)  the  microbes  may  be  so  altered  that  they  produce  attenuated  toxins.  Some 
authorities  have  surmized  that  as  drying  proceeds  the  microbes  perish,  first  at 
the  surface  of  the  cord,  and  then  progressively  towards  the  centre,  and,  therefore, 
that  the  efficacy  of  Pasteur's  treatment  depends  on  the  injection  of  small  but 
progressively  increasing  .^quantities  of  microbes.  But  the  microbes  are  already 


THE  RATIONALE  OF  ACQUIRED  IMMUNITY       247 

acquired  the  power  of  resisting  weak  toxins,  he  is  in  a  position  of 
advantage  from  which  he  can  react  to  the  stronger  toxins  and  so 
acquire  immunity.  In  these  instances,  then,  acquired  immunity  is 
nothing  other  than  a  '  use-acquirement,'  resulting  from  progressive 
habituation.  The  antitoxins  educate  the  phagocytes  till  they  are 
able  to  tolerate  the  strongest  toxins  and  destroy  the  microbes 
producing  them. 

413.  That  habituation  plays  a  great  part  in  the  acquirement 
of  immunity  is  evident  from  the  fact  that,  if  we  begin  with  small 
but  increasing  doses,  we  may  eventually  inject  very  large  doses 
of  diphtheria  toxin  into  a  horse,  without  making  him  ill,  though  his 
serum  becomes  poisonous  to  other  animals,  which,  of  course,  it 
would  not  be  were  his  immunity  due  to  chemical  neutralization. 
So  also,  by  beginning  with  small  doses  a  certain  degree  of 
immunity  against  morphia,  nicotine,  and  arsenic  may  be  achieved. 
It  is  evident,  therefore,  that  immunity  may  be  secured  with  com- 
parative ease  in  two  ways,  by  giving  weakened  toxins,  or  by  giving 
small  but  increasing  doses  of  unaltered  toxins.  The  chemical 
composition  of  morphia  and  nicotine  is  comparatively  simple. 
These  substances,  therefore,  cannot  be  altered  without  destroying 
them  as  poisons.  Arsenic  is  a  still  more  simple  substance.  But 
the  composition  of  the  microbic  toxins,  that  of  such  proteid 
vegetable  poisons  as  abrin  and  ricin,  and  that  of  such  animal 
poisons  as  snake  venom  is  very  complex.  Therefore  they  may 
be  altered  in  such  ways  as  to  leave  them  still  poisonous  but 
weakened  in  various  degrees.  If  food  be  swallowed,  it  is  digested 
by  the  pepsin  and  the  other  ferments  secreted  by  the  alimentary 
tract  and  passes  into  the  system  in  a  somewhat  altered  condition. 
Similarly  if  snake  poison  be  swallowed,  it  is  digested  and  some- 
what altered  so  that  it  enters  the  blood  in  an  attenuated  state  and 
educates  the  system  against  virulent  venom  injected  under  the 
skin.1  If  the  poison  gland  be  swallowed,  it  is  also  digested. 
Now  microbes,  during  recovery  from  disease  or  if  enclosed  in  a 
capillary  tube,  perish  though  not  in  contact  with  phagocytes. 

present  in  the  infected  person  in  numbers  sufficient  to  cause  disease,  that  is,  they 
are  present  in  such  numbers  that  the  phagocytes  cannot  overcome  them ; 
and  their  numbers  continually  increase.  According  to  this  hypothesis,  then,  if 
we  wish  to  cure  a  disease  due  to  an  increasing  number  of  microbes,  we  must  add 
to  the  multitude  from  extraneous  sources. 

1  Digestion  in  gastric  juice  of  spinal  cords  infected  with  rabies,  has  also  been 
practised,  especially  in  Italy  as  a  means  of  attenuating  the  virus  of  that  disease. 
If  a  series  of  injections  of  this  digested  material  be  made  into  sheep  an  antitoxic 
serum  may  be  obtained. 


248  ACQUIRED  IMMUNITY 

Presumably  the  same  digestive  substance  which  destroys  them 
when  enclosed  within  the  phagocytes  is  secreted  into  the  surround- 
ing medium  and  destroys  them  there — just  as  pepsin,  which  is 
harmless  to  the  stomach  cells  which  produce  it,  digests  food  at  a 
distance  from  them.  Moreover,  just  as  pepsin  digests  both  snake 
venom  and  the  gland  which  secretes  the  venom,  so,  presumably, 
the  ferments  secreted  by  the  phagocytes  digest  both  the  microbes 
and  their  toxins.  Of  the  existence*  of  these  digestive  ferments 
there  can  be  no  doubt.  Thus,  if  we  add  blood  from  a  person 
recovering  from  enteric  fever  to  a  medium  in  which  typhoid  bacilli 
are  contained,  the  behaviour  of  the  latter  indicates  injury. 

414.  If,  then,  this  theory  be  correct,  and  I   am  not  aware  of 
anything  known  to  us  which  contradicts  it,  antitoxic  serum  from 
a  horse  contains  substances — ferments  and  enzymes — which  are 
engaged  in  digesting  the  toxins  and   so  attenuating  them  ;  for 
which   reason  a  fatal  dose  of  toxin  is  rendered  harmless  when 
mixed  before  injection  with  its  equivalent  of  antitoxin  while  the 
effect  of  even  larger  doses  is  mitigated.     But,  what  is  even  more 
important,  it  contains  more  or  less  attenuated  toxins  which  form  a 
scale  up  which  the  cells  of  the  individual  into  whom  it  is  injected 
react  until  he  achieves  the  power  of  tolerating  the  strongest  toxins. 

415.  Given  suitably  attenuated  toxins  and  time  for  reaction, 
immunity  against  acute  disease  may  almost  always  be  secured. 
Thus,  if  an  individual  be  infected   with   rabies,  which  develops 
slowly,  there  is  usually  ample  time  if  treatment  be  begun  early. 
In  diphtheria,  which  develops  quickly,  days  and  hours  may  be 
of  vital  importance ;  but  since  we  are  able  to  pour  in  an  ample 
supply  of  antitoxin,  our  treatment  may  be  very  successful.     The 
vaccine  treatment  of  smallpox,  on  the  other  hand,  is  preventive 
not   curative.     It   is   useless  to   vaccinate    after  the   disease  has 
manifested  itself,  for  before  the  weaker  toxin  is  elaborated,  the 
sufferer  is  on  the  high  road  to  recovery,  or  is  past  help.1     Pre- 
sumably the  normal  process  of  acquiring  immunity  is  in  essence 
similar  to  that  which  occurs  when  antitoxins  are  artificially  intro- 
duced.    The  severity  of  the  disease  depends  in  part  on  the  resisting 
power  of  the  individual  attacked,  and  in  part  on  the  virulence  of 

1  It  is  remarkable  that  subcutaneous  injections  of  considerable  quantities  of 
vaccine  lymph  does  not  appear  to  have  been  tried  in  smallpox.  Theoretically 
such  treatment  should  be  excellent.  It  is  probable,  however,  that  the  majority 
of  deaths  amongst  sufferers  from  smallpox  are  caused  not  by  that  disease,  but  by 
subsequent  septic  infection  and  the  absorption  of  the  toxins  of  putrefaction. 
Even  so,  however,  if  the  injection  of  vaccine  lymph  caused  the  vesicles  to  abort, 
the  effect  would  be  curative. 


SYPHILIS  249 

the  microbes.  If  the  phagocytes  are  resistant  they  are  able  to 
produce  enzymes  which  attenuate  the  toxins,  thus  providing 
antitoxins,  and  recovery  follows.  If  their  resisting  power  is  low, 
they  are  paralysed  or  killed,  enzymes  are  not  produced,  a  scale  of 
attenuated  toxins  is  not  provided,  and  the  individual  does  not 
react,  but  perishes.  The  tobacco  smoker  does  not  acquire  increased 
resisting  power  against  any  other  toxin,  for  example,  he  is  not 
rendered  more  resistant  to  opium.  Similarly,  since  the  toxins  of 
every  disease  differ  from  those  of  every  other,  immunity  (i.e. 
labituation)  acquired  against  any  one  disease  confers  no  increase 
of  resisting  power  against  any  other. 

416.  Syphilis,  which  has  been  curiously  neglected  by  students 
of  acquired  immunity  but  which  is  often  quoted  by  medical 
supporters  of  the  Lamarckian  doctrine,  affords  very  instructive  and 
llustrative  data.  The  disease  is  caused  by  a  microbe,  the  spirochete 
pallidum.  It  has  been  said  that  offspring  may  be  infected  by 
either  parent,  but  certainly  infection  is  much  more  common  through 
the  mother.  If  it  be  true  that  healthy  mothers  sometimes  bear 
infected  children,  then,  in  such  cases,  the  microbes  must  have  been 
travelling  with  the  fertilizing  spermatozoon,  or  in  some  other  way 
which  I  cannot  imagine  have  entered  the  ovum  without  invading 
the  maternal  tissues.  The  microbe  of  Texas  fever,  a  disease  of 
cattle,  is  .  known  to  travel  with  the  germ-cells  of  the  tick  with 
which  the  cattle  are  infested.  The  child  in  utero,  is,  rightly 
speaking,  merely  a  parasite  on  the  mother.  It  adheres  to  her 
by  the  placenta,  through  which  it  receives  nutriment,  and  in  which 
the  thin-walled  maternal  and  fcetal  vessels  lie  in  close  contact  so 
that  fluids  with  dissolved  solids  and  gases  pass  from  one  to  the 
other,  whereas  solids  such  as  blood  corpuscles  and  microbes  do  not. 
In  some  diseases  of  which  syphilis  affords  by  far  the  greater 
number  of  examples,  injury  to  the  placental  vessels  may  occur  and 
result  in  the  passage  of  solids,  for  example  microbes.  Apparently 
the  toxins  of  syphilis  are  but  slowly  elaborated  and  are  not  very 
virulent.  Consequently  the  disease  is  of  gradual  development  and 
of  long  duration.  It  would  appear  that  the  microbes,  while  they 
are  yet  few  in  number,  are  at  first  confined  to  the  place  of  entry, 
where  they  are  protected  by  their  concentrated  toxins.  Later 
when  they  have  multiplied  and  the  resistance  of  the  phagocytes 
has  been,  for  the  time,  overcome  by  the  increased  abundance  of 
toxins,  they  spread  over  the  whole  system.  The  mother,  then, 
gradually  acquires  immunity.  Her  phagocytes  become  tolerant 
of  the  toxins  and  produce  enzymes  which  attenuate  them.  A 


250  ACQUIRED  IMMUNITY 

scale  is  thus  provided  up  which  she  reacts.  Her  foetus  receiving 
enzymes  and  attenuated  toxins  from  her  tends  to  acquire  immunity 
at  the  same  time. 

417.  But  young  individuals  are  usually  less  tolerant  of  disease, 
less  capable  of  acquiring  immunity,  more  liable  to  be  poisoned 
even  by  attenuated  toxins  than  older  individuals.1  Consequently 
in  the  earlier  stages  of  the  mother's  illness  the  foetus  tends  to 
perish.  In  the  later  stages,  protected  by  the  mother's  enzymes, 
and  little  injured  by  the  much  attenuated  toxins,  the  child  may  be 
born  with  every  appearance  of  health ;  but  after  birth,  when  both 
the  enzymes  and  the  attenuated  toxins  from  the  mother  have 
disappeared,  the  microbes  may  reassert  themselves,  and  the  child 
may  perish,  or  waste  and  sicken  for  a  time  till  its  own  immunity  is 
thoroughly  established.  If  the  placental  vessels  are  uninjured,  so 
that  only  the  mother  or  the  child  is  infected,  the  non-infected 
individual  tends  to  acquire  immunity  more  easily  and  quickly  than 
when  microbes  with  their  concentrated  toxins  are  present.  It 
undergoes,  in  fact,  a  serum  treatment  strictly  analogous  to  that 
which  has  proved  so  successful  in  diphtheria — or  rather  strictly 
analogous  to  that  by  which  we  secure  immunity  to  a  person  in 
imminent  danger  of  infection  by  diphtheria.  Consequently  a  non- 
infected  child,  born  to  an  infected  mother,  tends  to  acquire  im- 
munity and  survive,  though  it  is  possible  that  its  immunity,  being 
'  passive,'  may  not  be  permanent  Doubtless  if  a  mother,  who  has 
recovered,  becomes  pregnant  of  healthy  children,  she  confers  no 
immunity  on  them,  for  no  toxins  or  antitoxins  are  present  to  cause 
reaction.  So  also  a  mother  who  has  recovered  from  measles  or 
smallpox  confers  no  immunity  on  her  children  subsequently  con- 
ceived. But  doubtless,  also,  if  she  becomes  pregnant  of  an  infected 
child,  she  confers  immunity  ;  for  toxins  elaborated  in  the  child  pass 
to  her,  and  returning  as  antitoxins  induce  a  reaction  similar  to  that 
which  arises  in  the  children  she  bears  in  the  later  stages  of  her 
own  disease.  At  any  rate,  as  far  as  I  am  aware,  no  instance  is 

1  Doubtless  this  is  because  they  represent  a  stage  in  the  life-history  at  which 
powers  of  making  resistance  had  not  been  evolved,  or  so  much  evolved.  Young 
embryos  represent  a  stage  when  the  very  power  of  making  use-acquirements  did  not 
exist.  Probably,  therefore,  the  survival  even  of  foetuses  is  determined  less  by  their 
own  resisting  powers  than  by  those  of  their  mothers.  It  must  be  noted,  however, 
that  since  variations  occur  in  all  stages  of  development,  and  since  children  as 
well  as  adults  are  selected  by  most  diseases,  they  are  usually  more  resistant  than 
their  remote  ancestors  to  diseases  of  which  the  race  has  had  experience — as  is 
proved,  for  example,  by  the  fact  that  English  children  are  more  resistant  to 
tuberculosis  than  American  Indians,  who  therein  resemble  the  ancestors  of  the 
English  (see  §  442). 


EHRLICH'S  HYPOTHESIS  251 

mown  of  a  mother  who  had  suffered  from  syphilis  bearing  infected 
:hildren  to  a  diseased  father,  though  probably  the  union  of  such 
nothers  with  such  fathers  is  not  very  rare.  Obviously,  a  father 
can  never  confer  immunity,  for  immunity  is  a  reaction  made  by 
phagocytes  and  perhaps  some  other  cells  functionally  concerned, 
not  by  the  germ-cell,  the  function  of  which  is  reproduction. 

418.  It  is  clear,  then,  that  in  syphilis  there  is  no  transmission 
of  acquirements  in  the  Lamarckian  sense — that  is,  the  child  does 
not  develop  under  the  stimulus  of  nutrition  characters  which  the 
parent  developed  under  the  stimuli  of  injury  and  use.     The  child 
acquires  the  disease  and,  if  it  survives,  immunity,  as  the  parent  did, 
through  infection  with  a  microbe  which  has  previously  lived    in 
another  person.     Therefore  the  expression  '  hereditary  syphilis  '  is 
erroneous.     It  would  be  as  reasonable  to  speak  of  a  bullet  which 
passed  through  the  mother  and  lodged  in  the  child  as  a  hereditary 
bullet. 

419.  An   explanation   of   immunity  at  present  very  popular 
amongst    bacteriologists,     is    Ehrlich's    'side-chain'    hypothesis, 
a   chemico-physiological    attempt   to   interpret   the   facts.      This 
hypothesis  resembles  Darwin's  theory  of  pangenesis,  Weismann's 
theory  of  germinal  selection,  Mendel's  theory  of  segregation,  and 
many  others,  in  that  it  is  not  founded  on  actual  evidence.     It  seeks 
to  account  for  facts  believed  to  be  true  by  assuming  conditions  not 
yet  ascertained  to  exist.     Ehrlich  supposes  that  the  cells  of  the 
body   possess   side-chains   composed   of  molecules,  receptors   as 
they  are  termed,  the  primary  function  of  which  is  to  attach  to  the 
cells  various  kinds  of  food  molecules,  fats,  carbohydrates,  oxygen 
and   the   like.     The   receptors,  therefore,  are  of  different   kinds. 
In  addition  to  having  an  affinity  for  this  or  that  kind  of  food- 
molecule,  this  or  that  kind  of  receptor  may  have  an  accidental 
affinity  for  this   or   that  kind   of  toxin — an  affinity   which   is   a 
positive  and  fatal  disadvantage,  for  the  cell  is  thereby  rendered 
susceptible    to     poison.       If    much    toxin     be     present,    many 
receptors  combine  with  its  molecules  and  the  cell   perishes.     If 
little  is  present,  some  of  the  side-chains  alone  perish  and  are  shed, 
combined   with   the   now   inert  toxin,    and   undergo   subsequent 
disintegration   in   the   blood   serum.     This   may   be   termed   the 
chemical   part   of    the    theory.      The   physiological   part   is   the 
supposition  that   the   loss   of  side-chains  stimulates  the  cells   to 
excessive  production   of  them.      The   appropriate   receptors   are 
thus  set  free  in  the  blood  which  consequently  becomes  antitoxic. 
Immunity  is  thus  acquired.     It  is  not  stated  whether  this  excessive 


252  ACQUIRED  IMMUNITY 

production  and  shedding  of  receptors  occurs  normally  in  the 
presence  of  over  much  nutriment.  Presumably,  it  does  not,  since 
the  free  receptors  would  render  the  food  incapable  of  being  taken 
up  by  the  cells  and  thus  over  much  nutriment  would  eventually 
be  equivalent  to  too  little,  and  starvation  would  result.  In  any 
case,  the  power  of  acquiring  immunity  is,  according  to  Ehrlich's 
theory,  an  accidental  accompaniment  of  the  power  of  assimilating 
nutriment. 

420.  On  the   other   hand,  inborn    immunity — the  kind  which 
prevents  an  animal  ever  acquiring  a  disease — is  thought  to  depend 
(i)  on  a  lack  of  receptors  which  have  an  affinity  for  the  toxins  of 
that  particular  disease,  or   (2)  on    the   normal  presence   of  free 
receptors   in   the   blood — that   is,   on   receptors  which   for  some 
reason  are  free  in  the  serum,  though  disease  has  not  stimulated 
their  super-production.     Such   non-bacterial  poisons  as  morphia, 
nicotine,    arsenic  and   the  like — which  are  not   of  very  complex 
composition,  are  supposed  to  affect  not  the  side-chains  especially, 
but  the  whole  cell,  which  is  thus  poisoned  or  else  acquires  resisting 
power  against   them    in  ways  that  differ  from    that   in  which  it 
acquires  immunity  against  the  proteid  poisons. 

421.  Obviously,   the    physiological    part   of   Ehrlich's   theory 
attributes  immunity  to  use-acquirement.     It  attempts  to  explain 
up  to  a  certain    point   how  toleration   of  toxins  arises ;    that  is, 
Ehrlich  supposes  that  toxins  stimulate  cells  to  the  production  of 
receptors.     But  the  central  mystery  of  how  it  happens  that  the 
stimulation  has  the  effect  alleged,  remains  unsolved.     Instead  of 
direct  digestion   by  enzymes,  neutralization  and  subsequent  dis- 
integration (which  must  be  due  to  some  form  of  digestion),  are 
imagined.     But,  since  it  is  admitted  that  toleration  of  poisons  of 
simple  composition,  such  as  morphine  and  nicotine,  is  not  due  to 
an   increased   production    of  receptors   but   merely   to   increased 
toleration   by  the   cell    itself,    the   necessity   of  postulating   the 
existence  of  the  receptors  is  not  very  evident.     No   account   is 
taken  of  the  evolution  of  the  power  of  attack  in  bacteria  nor  of 
resisting  power  in   the  species  attacked.     In  fact   the  whole  in- 
dubitable truth  of  evolution  is  ignored.     Disease  is  treated,  not  as 
part  of  the  normal  environment  as  it  really  is,  but  as  an  accident 
which  is  resisted   by   accident.     Immunity,  inborn  and  acquired, 
is  regarded,  not  as  a  product  of  protective  evolution,  but   as   a 
fortunate  '  fluke.' 

422.  Some  varieties  of  animals  (e.g.  white  rats)  are  normally 
immune  to  certain  diseases  to  which  allied  varieties  or  species 


ACQUIRED  IMMUNITY  AN  ADAPTATION          253 

that  use  similar  food  are  liable.  Some  individuals  of  a  species 
(e.g.  man)  are  immune  to  disease  (e.g.  scarlatina),  to  which  other 
individuals  are  liable.  Many  species  of  animals  normally  immune 
to  this  or  that  disease,  are  liable  to  infection,  if  the  health  be 
lowered  as  by  abnormal  heat  or  cold.  Antitoxins  ('receptors') 
may  be  obtained  from  the  dead  or  dying  cord  of  a  rabbit  which 
was  suffering  from  rabies  and  would  infallibly  have  perished  if 
it  had  not  been  killed ;  that  is,  though  receptors  are  not  produced 
in  the  living  animal  in  sufficient  abundance  to  neutralize  the  toxins, 
and  though  they  cannot,  of  course,  be  produced  by  the  dead  cells 
of  the  drying  cord,  yet  in  the  latter  they  are  thought  to  be  in 
abundance.  Snake  venom,  in  doses  lethal  a  thousand  times  over 
if  injected  under  the  skin,  confers  immunity  if  swallowed.  Whence 
the  receptors  in  the  latter  case  ?  All  these  facts  are  inconsistent 
with  the  side-chain  theory,  which  with  many  other  bacteriological 
hypotheses  would,  I  think,  never  have  been  formulated  had  their 
authors  taken  the  whole  of  the  facts  into  account — had  they 
paused  to  consider  that  living  nature  is  a  product  of  evolution,  not 
of  miracle. 

423.  If  the  reader  bears  in  mind  the  facts  of  adaptation,  if  he 
remembers  that  almost  every  important  character  is  an  adaptation, 
I  think  that  he  must  conclude  that  acquired  immunity  is  not  an 
isolated  phenomenon  nor  a  '  fluke,'  but  essentially  a  use-acquire- 
ment entirely  comparable  to  other  use-acquirements  in  the  sense 
that  the  power  of  acquiring  it  has  been  evolved.  I  think,  also,  he 
will  find  the  strongest  reasons  for  believing  that  the  process  by 
which  this  habituation  is  achieved,  is,  in  the  case  of  virulent 
complex  toxins  at  least,  one  of  reaction  from  weak  to  stronger 
toxins,  the  weak  toxins,  the  so-called  anti-toxins,  being  nothing 
other  than  stronger  toxins  that  have  been  more  or  less  digested, 
and  in  this  way  chemically  altered  by  enzymes  secreted  by  the  cells.1 

1  All  the  evidence  points  to  the  fact  that  acquired  immunity  is  especially  a 
reaction  to  the  extra-cellular  toxins  (exotoxines) — those  that  are  secreted  by  the 
microbes  into  the  surrounding  medium,  not  retained  within  themselves.  Thus, 
while  an  experience  of  a  few  days  confers  immunity  to  such  diseases  as  smallpox 
and  measles  in  which  symptoms  of  toxin  poison  are  much  in  evidence,  life-long 
experience  confers  no  increase  of  resisting  power  against  tuberculosis  or  leprosy — 
even  when  the  sufferer  is  but  slightly  infected  and  his  natural  powers  of  resistance 
are  but  little  lowered.  Effective  antitoxic  treatment,  therefore,  would  seem 
impossible  in  such  cases.  Very  scanty  success,  or  no  success  has  attended  all 
attempts  to  deal  thus  with  maladies  which,  being  experienced,  do  not  naturally 
give  rise  to  acquired  immunity  in  resistant  individuals.  The  celebrated  tuberculin 
treatment  of  phthisis  is  a  case  in  point.  Tuberculin  is  prepared  from  dried  tubercle 
bacilli  and  contains  therefore  an  intra-cellular  toxin  (endotoxine).  It  seems  to 


254  ACQUIRED  IMMUNITY 

424.  The  outline  I  have  attempted  to  give  of  the  process  of 
digestion  is,  of  course,  even  if  correct  in  all  its  facts  and  inferences 
a  mere  sketch.     Each  species  of  bacteria  may  secrete  not  only  one 
but  two  or  more  toxins  complementary  to  one  another.     Thus 
there  is  ample  evidence  of  the  existence  in  acute  diseases  of  toxins 
which  are  retained  within  the  microbes,  in  addition  to  those  which 
are  passed  into  the  surrounding  medium.     Probably  the  organisms 
of  the  chronic  diseases  (e.g.  tuberculosis)  are  protected-  more  especi- 
ally by  the  former,  those  of  the  acute  diseases  (e.g.  small-pox)  by  the 
latter,  whereas  those  of  the  sub-acute  diseases  (e.g.  syphilis)  depend 
in  a  more  equal  degree  on  both.     It  is  significant  that  an  extract 
obtained  from  dead  tubercle  bacilli  is  very  poisonous,  while  one  simi- 
larly obtained  from  diphtheria  bacilli  is  not.     Again,  there  is  some 
evidence  that  one  kind  of  enzyme  acts  directly  against  the  microbes 
and  another  against  their  toxins.    The  cells,  therefore,  may  secrete, 
not  one  kind  of  enzyme,  but  perhaps  several.     The  same  enzyme 
may  not  protect  against  every  disease.     The  process  of  digestion 
may  not  be  continuous,  but  may  proceed  by  well  marked  steps  in 
which  various  cell  products,  globulins,  lysins,  alexines,  opsonins, 
and  the  like  successively  take  part.     As  far  as  I  am  able  to  judge, 
however,  no  matter  how  complicated  the  process,  it  is  somewhat  of 
the  nature  I  have  attempted  to  describe. 

425.  Inborn  immunity  on  the  other  hand  must  in  each  case  be 

have  some  curative  properties,  which  depend  apparently  on  an  increase  of  in- 
flammation round  the  foci  of  infection  which  leads  to  necrosis  and  sloughing  of 
the  diseased  tissues  ;  but  there  is  no  evidence  that  it  conduces  to  that  toleration, 
that  acquired  immunity,  to  the  attainment  of  which  the  antitoxic  treatment  of 
acute  disease  is  so  great  a  help.  The  antitoxic  treatment  of  such  troubles  as 
alcoholism  and  morphomania  has  also  been  tried — with  declared  success  by  the 
originators  of  the  treatment,  with  ill-success  by  all  who  followed  them.  Doubt- 
less serum  treatment  of  a  tendency  to  fatigue  by  means  of  an  antitoxin  obtained 
from  very  tired  animals  will  one  day  be  attempted,  and  will  meet  with  the  same 
unsatisfactory  sort  of  success.  Some  of  the  hypotheses  formulated  and  acclaimed 
by  bacteriologists  are  of  a  kind  to  fully  justify  the  endeavour.  The  speed  with 
which  immunity  is  acquired  bears  an  evident  relation  to  the  abundance  of  the 
extra-cellular  toxins  and  the  rapidity  with  which  they  are  produced  by  the 
microbes.  All  the  cells  of  the  body  are  affected  by  them  and  all  those  which  are 
functionally  concerned  in  the  acquirement  of  immunity  tend  to  react.  In  the 
case  of  the  intra-cellular  toxins  only  those  cells  which  ingest  the  microbes  are 
affected.  Possibly  this  is  the  reason  why  immunity  is  acquired  in  the  one  case 
and  not  in  the  other.  The  duration  of  immunity,  which  is  usually  life-long  in 
some  diseases  and  of  short  duration  in  others,  depends  on  factors  which  are  quite 
unrecognized.  It  is  sometimes  said  that  one  attack  of  certain  diseases  (e.g. 
diphtheria)  in  which  the  period  of  immunity  is  short,  predisposes  to  subsequent 
attacks  ;  but  the  truth  of  this  surmise  is  very  doubtful.  An  attack  of  such  a 
malady  indicates  that  the  individual  is  susceptible  ;  subsequent  attacks  probably 
indicate  no  more  than  a  recrudescence  of  this  susceptibility. 


INBORN  AND  ACQUIRED  IMMUNITY  255 

due  to  one  of  two  very  different  causes  ;  a  very  high  resisting  power 
on  the  part  of  the  individual  attacked,  or  to  a  low  attacking  power 
on  the  part  of  the  microbes.     The  high  resisting  power  is  due  to 
stringency  of  selection  affecting  the  species  possessing  it ;  the  low 
attacking  power  is  due  to  lack  of  selection  amongst  the  microbes. 
Thus  human  races  that  have  been  much  afflicted  by  tuberculosis 
are,  as  compared  to  other  human  races,  especially  resistant.     Dogs 
on  the  other  hand  are  almost  quite  immune.     Since  we  have  no 
reason  to  suppose  that  these  animals  have  ever  suffered  from  the 
disease,  we  are  driven  to  the  conclusion  that  the  environment  they 
offer  is  unsuitable  to  the  tubercle  bacilli.     It  is  one  to  which  their 
evolution  has  not  adapted  them.     It  must  be  noted,  however,  that 
an  evolution,  which  fits  a  race  for  a  particular  environment,  does 
not  necessarily  unfit  it  for  existence  in  another,  and,  within  limits, 
a  different  one.     Thus  many  European  plants  and  animals,  in- 
cluding man   himself,  flourish  exceedingly  in  New  Zealand  and 
elsewhere.     So  also  the  bacillus  tuberculosis,  which,  so  far  as  we 
know,  has  never  afflicted  wild  guinea  pigs,  is  very  deadly  to  them 
in  captivity.      In  rare  cases  inborn  immunity  appears  to  be  a 
correlate   of    other   and    apparently   quite   unrelated   characters. 
Thus,  unlike  coloured  varieties,  white  rats  are  immune  to  anthrax. 
426.  The  main  purpose  of  the  present  chapter  is  to  establish 
a   clear   distinction    between   inborn    and   acquired    immunity — 
between  the  kind  of  immunity  which  arises  under  the  stimulus  of 
nutrition  and  that  kind  which  develops  through  individual  experi- 
ence of  disease.     To  achieve  this  object  we  have  been  forced  to 
discuss  the  rationale  of  acquired  immunity.     The  two  kinds  are 
constantly  confused.     Thus  in  medical  discussions,  one  has  only 
to  maintain  that  parental  diseases  and  acquired  immunity  are  not 
1  hereditary,'  and  some  one  is  sure  to  retort  that  in  both  instances 
the  contrary  is  constantly  observed  in  syphilis.     Many  doctors  are 
still  convinced  that  ' common  sense '   demands   a   belief  in   the 
Lamarckian  doctrine.     Certainly  nearly  all  doctors  are  convinced 
on  grounds  of  common  sense  that  ill-health  tends  to  so  affect  the 
germ-plasm  that,  in  consequence,  offspring  of  unhealthy  people 
are  commonly  born  degenerate.     In  other  words  they  believe  that 
parental  disease  is  a  frequent  cause  of  variations  in  offspring.     We 
have  already  discussed  this  problem  somewhat  in  detail,  but  it  is 
of  great  practical  as  well  as  theoretical  importance  and  will  repay 
further  study.     The  ground  is  now  cleared  of  possible  misconcep- 
tions and  we  may  proceed  to  discuss  it  in  comfort. 


CHAPTER   XIII 
THE  PRESENT  EVOLUTION  OF  MAN 

The  conditions  under  which  infection  occurs — Inborn  immunity  develops  in 
the  individual  under  the  stimulus  of  nutriment — Acquired  immunity  under  that 
of  use — Theories  of  the  causation  of  variations  and  the  facts  of  disease — The 
decisive  nature  of  the  evidence  furnished  by  disease — Malaria — Tuberculosis — 
The  air-borne  diseases. 


W1 


427.  ^["^  J"E.  saw  in  the  eleventh  chapter  that,  with  the  excep- 
tion of  alcohol,  opium,  and  perhaps  one  or  two 
other  narcotics,  microbic  disease  is  the  only  agency 
which  is  stringently  selective  amongst  civilized  men.  Speaking 
generally,  in  England,  for  example,  the  people  who  survive  and 
leave  offspring  are  not  those  who  escape  contact  with  the  microbes 
of  such  prevalent  diseases  as  measles  and  whooping-cough,  but 
those  who  are  resistant  to  them.  Selection  implies,  of  course, 
variations  in  resisting  power,  and  no  one  will  deny  that  men  differ 
naturally  in  this  particular  as  in  all  others.  Again,  no  one  will 
deny  that  resisting  power  against  one  disease  does  not  necessarily 
imply  resisting  power  against  any  other.  The  selection  is,  in  fact, 
'  specific.'  Each  disease  chooses  its  own  special  victims,  and  is  the 
cause  of  an  evolution  only  against  itself.  On  the  other  hand,  no 
one  who  has  studied  diseases  doubts  that,  owing  to  fluctuations  in 
vitality  and  environment,  individuals  tend  to  alter  from  time  to 
time  in  their  powers  of  resisting  it.  The  man  who  is  very  resistant, 
may  become  less  resistant  through  the  operation  of  some  cause 
which  lowers  his  vitality,  while  he  who  is  very  susceptible  may  be 
rendered  more  or  less  so  through  changes  in  health  and  sur- 
roundings. Nevertheless,  the  truth  holds  that  the  naturally  more 
resistant  tend  always,  under  any  condition,  to  survive  in  greater 
numbers  than  the  more  susceptible.  Lastly,  selection  is  not 
equally  stringent  in  all  environments,  nor  at  all  times  in  the  same 
environments.  It  has  been  ascertained,  experimentally,  that  the 
dosage  of  microbes  plays  a  large  part  in  the  causation  of  infec- 
tion, and,  therefore,  in  the  causation  of  acquired  immunity  or 
death.  The  microbes  of  disease  are  much  more  numerous  in  some 

256 


ACUTE  AND  CHRONIC  DISEASES  257 

situations  than  in  others.  We,  in  England,  contract  almost  all 
our  diseases  in  dwelling-houses  or  in  places  of  popular  assembly, 
such  as  schools  and  churches.  In  the  slums  of  cities  where  over- 
crowding is  greatest,  the  separation  between  the  sick  and  the 
healthy  most  imperfect,  the  dilution  of  the  dosage  with  fresh 
incoming  air  most  incomplete,  and  the  general  nutritive  and 
sanitary  conditions  worse,  selection  is  more  stringent  than  in  better 
houses  and  in  rural  districts.  Such  very  common  diseases  as 
measles,  chicken-pox,  and  whooping-cough  are  usually  always 
present  (endemic)  in  towns,  whereas  in  the  country  and  even  more 
in  remote  islands,  such  as  the  Hebrides,  they  tend  to  be  more 
distinctly  epidemic.  That  is,  in  towns  the  exposure  of  susceptible 
people  to  large  doses  is  very  frequent,  while  in  the  country  it  is 
more  exceptional. 

428.  We  saw  also  that  all  microbic  diseases  may  be  placed  in 
one  or  other  of  two  categories.  On  the  one  hand  are  those 
diseases  against  which  immunity  cannot  be  acquired,  and,  on  the 
other,  those  against  which  it  may  be  acquired — acquired  immunity 
being  an  entirely  specific  reaction  which  follows  individual  experi- 
ence of  disease,  and  which  in  every  case  is  of  avail  only  against  the 
particular  disease  which  has  been  experienced.  It  is  quite  distinct 
from  '  innate '  immunity,  which  (though  it  is  also  specific)  does  not 
follow  but  precedes  experience  of  the  microbes,  and  which  arises 
therefore  like  eyes,  ears,  hair,  and  teeth,  as  a  nutritional  character. 
Tuberculosis  and  leprosy  are  typical  examples  of  diseases  against 
which  immunity  cannot  be  acquired.  No  doubt,  in  a  sense, 
immunity  may  be  acquired  against  some  of  them  ;  that  is,  owing  to 
improved  health  and  vitality,  an  infected  person  may  recover  and 
live  immune;  but  this  is  not  what  is  meant  by  the  technical  expres- 
sion 'acquired  immunity.'  On  the  other  hand,  a  person  maybe 
'  innately '  immune  against  such  typically  acute  diseases  as  measles 
and  influenza.  That  is,  he  resists  infection  though  exposed  to 
doses  which  would  give  rise  to  disease  in  the  ordinary  individual 
who  has  not  acquired  immunity.  But  in  the  case  of  such  diseases,  in 
the  vast  majority  of  instances,  people  differ,  not  so  much  because  they 
resist  infection,  for  nearly  all  contract  each  disease  if  sufficiently 
exposed  to  infection,  as  because  they  recover  more  or  less  easily.1 

1  Inborn  immunity,  though  rare  in  measles  and  so  rare  in  smallpox  that 
formerly  when  the  disease  was  prevalent  an  unmarked  skin  was  in  itself  regarded 
as  an  exceptional  beauty,  is  common  enough  in  some  acute  diseases.  Thus, 
though  constantly  exposed  to  infection,  I  have  never  contracted  diphtheria  nor 
scarlatina.  Probably,  in  the  case  of  such  diseases,  the  two  forms  of  immunity 
are  evolved  concurrently. 

17 


258  THE  PRESENT  EVOLUTION  OF  MAN 

It  follows,  if  there  is  any  truth  in  the  theory  of  evolution 
through  Natural  Selection,  that  a  race  much  afflicted  by  a  chronic 
disease — for  example,  tuberculosis — should  evolve  inborn  immunity 
against  it ;  whereas,  if  afflicted  by  an  acute  disease — for  example, 
measles — it  should  tend  to  develop  an  inborn  power  of  acquiring 
immunity.  Both  inborn  immunity  and  the  power  of  acquiring 
immunity  arise  in  the  individual  through  the  experience  his  race 
has  had  of  disease.  They  are  nutritional  characters.  But  actual 
acquired  immunity  arises  in  the  individual  through  his  own 
personal  experience  of  disease.  So  also  a  man's  hand  and  his 
power  of  acquiring  callosities  on  it  are  due  to  an  evolution  in 
his  race  which  enables  him  to  develop  those  characters  under  the 
influence  of  nutrition  ;  but  the  actual  callosities  are  due  to  his  own 
experience  of  rough  work. 

429.  Again,  we  have  seen  that  there  are  several  theories  of 
evolution,  each  with  its  corresponding  theory  of  heredity.     First, 
there  is  the  theory  of  an  internal  adaptive   growth-force,  which 
supposes  that  variations  tend,  on  the  whole,  to  be  adaptive.     This 
hypothesis,  which   is    founded  purely  on    an    appeal   to   miracle, 
need  not  be  considered  further.     Science  ought  not  to  appeal  to 
the  supernatural  until,   at  least,  it  has  been  demonstrated  that 
natural    interpretations    are    impossible.      Second,    there   is   the 
Lamarckian  doctrine,  which  supposes  that  characters  acquired  by 
parents  under  the  influence  of  use  or  injury,  tend  to  be  reproduced 
by  offspring  under  the  stimulus  of  nutriment.     Third,  there  is  that 
very  popular  theory  of  heredity  which  supposes  that  variations 
commonly  arise  through  the  direct  action  of  the  environment  on 
the  germ-plasm.     This  hypothesis  of  the  causation  of  variations 
is  usually  associated  with  the  doctrine  of  Natural  Selection,  but 
is  clearly  incompatible  with  it.     Examined  closely,  we  find  that 
it  implies  a  theory  of  racial  change,  but  not  adaptive  change.     It 
implies,  in  fact,  that  species  drift  helplessly  under  the  influence  of 
the  environment  in  directions  which  may  or  not  be  adaptive,  but 
which  can  very  rarely  be  adaptive.     Lastly,  there  is  the  theory 
that  the  mass  of  variations  are  spontaneous,  and  that  they  occur 
all  round  the  specific  mean,  and,  therefore,  that  the  germ-plasm 
(in  so  far  as  its  hereditary  tendencies  are  concerned)  is  highly 
insusceptible   to   the   direct   action    of    the    environment.      This 
theory,  and  this  alone,  is  compatible  with  the  doctrine  of  Natural 
Selection.      If  only  we  think  closely  and  clearly,  we  find  also  that 
it  is  the  only  theory  which  fits  in  with  the  facts  of  adaptation. 

430.  Now,  which  theory  of  heredity  is  borne  out  by  human 


THE  RACIAL  EFFECTS  OF  DISEASE  259 

experience  of  diseases?  If  the  Lamarckian  doctrine  be  true,  all 
races  exposed  to  such  chronic  maladies  as  tuberculosis  should 
steadily  deteriorate ;  for  by  such  maladies  the  individual  is  never 
strengthened  in  any  known  way,  but,  on  the  contrary,  always 
injured.  His  resisting  power  is  lowered.  Therefore,  no  matter 
how  slight  and  partial,  how  fitful  and  faint  the  inheritance  of 
parental  injury,  yet  the  effects  accumulating  during  many  genera- 
tions should  at  last  cause  the  race  to  trend  towards  extinction. 
Is  it,  then,  the  fact  that  races  afflicted  by  tuberculosis,  or  any 
other  agency  which  causes  chronic  ill-health,  are  steadily  deterio- 
rating, steadily  becoming  less  and  less  capable  of  existence?  On 
the  other  hand,  acute  maladies  confer  a  great  measure  of  resisting 
power  on  individuals  who  have  experienced  them  and  survived. 
If  this  be  inherited,  no  matter  how  faintly  and  fitfully,  the  race 
should  in  time  develop  absolute  inborn  immunity,  absolute  in- 
capacity to  acquire  disease.  Is  it,  then,  the  fact,  that  races  which 
have  long  been  afflicted  by  such  acute  maladies  as  measles, 
chicken-pox,  whooping-cough,  and  the  like,  have  become  quite 
immune  to  infection  ?  Evidently  the  Lamarckian  doctrine  implies 
racial  effects  due  to  disease  which  are  very  remarkable.  Each 
chronic  disease  must  weaken  the  race  till  it  perishes,  each 
acute  disease  must  strengthen  it  till  it  is  quite  immune  to  that 
disease. 

431.  The  hypothesis  that  variations  are  caused  by  the  direct 
action  of  the  environment,  though  often  confused  with  the 
Lamarckian  doctrine,  is  quite  distinct  from  it.1  It  supposes,  not 
that  the  characters  which  arise  in  the  parent  through  use  or  injury 
are  reproduced  by  the  child  under  the  influence  of  nutrition,  but 
merely  that  nutritive  substances,  waste  products,  toxins,  and  the 
like,  circulating  in  the  blood,  or  otherwise  acting  on  the  germ- 
cells,  tend  to  alter  the  hereditary  tendencies  in  the  germ-plasm  in 
some  definite  way — in  such  a  way  that  the  individual  who 
springs  from  the  germ-cell  is  injured  or  benefited,  weakened  or 
strengthened.  At  first  sight  this  hypothesis  is  much  more  probable 
than  the  Lamarckian  theory.  But  it  is  only  reasonable  to  suppose 
that  if  the  germ-plasm  is  altered  at  all  by  the  direct  action  of  the 
environment,  it  is  injured  and  devitalized,  not  benefited  by  ex- 
posure to  the  toxins  of  acute  diseases  or  by  the  general  inter- 
ference with  nutrition  which  accompanies  the  chronic  maladies. 
At  any  rate,  while  it  has  often  been  held  that  parental  ill-health 
is  a  cause  of  filial  degeneration,  no  one  has  suggested  that  syphilis, 

1  See  §  98. 


26o  THE  PRESENT  EVOLUTION  OF  MAN 

tuberculosis,  malaria,  measles,  or  any  other  disease  or  ill-condition 
suffered  by  parents  increases  the  vitality  of  their  offspring.  If, 
then,  this  theory  is  correct,  all  races  afflicted  by  any  sort  of  disease 
should  steadily  drift  towards  extinction. 

432.  Lastly,  if  the  theory  that  the  vast  majority  of  variations 
are  spontaneous,  be  true,  and,  therefore,  if  the  doctrine  of  Natural 
Selection  be  correct,  then  every  prevalent  and  lethal  disease  should 
be  the  cause  of  protective  evolution  against  itself.  Diseases  which 
are  not  prevalent  or  not  lethal  should  cause  no  racial  change. 
Prevalent  and  lethal  chronic  diseases,  since  the  survivors  from 
them  are  people  who  resist  infection,  or  who,  if  they  recover  from 
infection,  do  so  only  because  their  vitality  is  improved,  not  because 
they  undergo  that  peculiar  reaction  known  as  acquired  immunity, 
should  cause  an  evolution  of  inborn  immunity — an  evolution  of  an 
inborn  power  of  resisting  infection.  Prevalent  and  lethal  acute 
diseases,  since  the  survivors  from  them  do  not,  as  a  rule,  resist 
infection,  but  merely  when  infected  tend  to  recover  within  a 
definite  time,  should  cause  an  evolution  of  the  power  of  acquiring 
immunity  under  the  experience  of  disease.  In  other  words,  the 
evolution  should  be  such  that,  in  the  case  of  chronic  maladies, 
immunity  should  develop  in  the  individual  under  the  stimulus  of 
nutrition,  whereas  in  the  case  of  acute  maladies  it  should  develop 
in  him  under  the  stimulus  of  use.  Thus,  if  the  theory  of  spon- 
taneous variations  and  of  Natural  Selection  be  true,  the  individuals 
of  a  race  that  has  been  long  and  severely  afflicted  by  tuberculosis 
should,  as  a  rule,  display  a  greater  innate  power  of  resisting  infec- 
tion, or,  if  infected,  of  withstanding  the  malady,  than  individuals 
of  races  that  have  been  less  or  not  at  all  afflicted.  A  race  afflicted 
by  measles  should  display  no  greater  power  of  resisting  infection 
than  any  other  race,  but  a  much  greater  faculty  of  recovering  by 
the  acquirement  of  immunity  than  races  that  have  had  less  experi- 
ence of  the  disease.  On  the  other  hand,  races  that  have  been 
afflicted  by  such  non-lethal  diseases  as  chicken  -  pox l  should 
possess  a  power  of  resistance  no  greater  than  that  displayed  by 
races  that  have  had  no  previous  experience.  Moreover,  in  all 
cases  the  resisting  power,  whether  inborn  immunity  or  the  inborn 
power  of  acquiring  immunity,  should  be  specific.  That  is,  the 
effect  of  each  disease  on  human  races  should  be  an  increased 

1  In  1905  "  chicken-pox  is  said  to  have  claimed  ninety-three  victims,  but  it 
is  at  least  probable  that  some  of  the  latter  were  unrecognized  cases  of  the  graver 
malady  "  (smallpox). — Sixty -eighth  Annual  Report  of  the  Registrar-General  of  Births, 
Deaths,  and  Marriages  in  England  and  Wales,  p.  Ixxix. 


MATERIALS  FOR  STUDY  261 

power  of  resisting  it  and  nothing  more.  The  race  should  not  gain 
in  beauty  or  muscular  strength  or  size  or  anything  of  the  sort.1 
Of  course,  it  is  possible  that  this  or  that  character  may  in  the 
future  be  found  to  be  correlated  to  susceptibility  to,  or  to  power  of 
resisting  this  or  that  disease,  but,  to  the  best  of  my  knowledge, 
nothing  of  the  kind  has  yet  been  discovered.2 

433.  Very  plainly,  disease  furnishes  ideal  material  for  investi- 
gation of  that  most  important  problem  of  heredity,  the  causation 
of  variations.  The  acquirements  made  under  the  influence  of 
injury  (e.g.  in  such  chronic  maladies  as  tuberculosis),  or  of  use 
(e.g.  in  such  acute  complaints  as  measles),  are  very  striking  and 
peculiar,  and  in  the  case  of  many  diseases  and  many  races  have 
been  made  by  every  generation  for  unnumbered  generations.  The 
germ-cells  are  often  literally  bathed  in  toxins,  it  may  be  for  pro- 
longed periods,  as  in  syphilis  and  malaria.  Their  nutrition  is 
interfered  with  for  even  longer  periods  in  such  complaints  as 
tuberculosis  and  leprosy.  Our  opportunities  for  observation  are 
particularly  good,  for  every  one  of  us  has  had  personal  experience 
of  illness,  and  is  acquainted  with  numerous  cases  of  it.  Any 
amount  of  precise  statistical  evidence,  furnished  by  Departments 
of  Public  Health,  concerning  the  different  effects  of  disease  on 
different  races,  is  available.  Every  instance  of  the  birth  of  a  child 
to  a  parent  who  is  or  has  been  diseased  constitutes  an  experiment 
which  is  as  stringent  as  any  that  can  be  consciously  devised,  but 
which  possesses  in  addition  the  advantage  that  it  is  made  under 
conditions  that  are  normal  to  the  species.  Like  many  other 
experiments,  this  experiment  has  the  disadvantage  that  the  effect 
produced  on  the  offspring,  if  any,'*may  be  so  small  as  not  to  be 
observable,  or  it  may  be  so  confused  with  spontaneous  variations 
as  not  to  be  detectable  ;  but  in  the  case  of  every  disease  we  are 
able  to  compare  many  races  which  have  suffered  much  and  long 

1  It  seems  hardly  necessary  to  insist  on  this,  but  various  critics  have  thought 
it  necessary  to  declare  that  there  is  no  evidence  that  much  experience  of  disease 
produces  the  '  finest  race.' 

2  The  dark  colour  of  negroes  has  been  thought  to  be  correlated  to  their  high 
powers  of  resisting  malaria.     But  many  black  races,  for  example  some  Polynesians, 
are  highly  susceptible,  and  some  white  races  are  relatively  resistant.     Thus  malaria, 
which  destroyed   an  invading  British  army  as  a  fighting  force,  left  the  inhabi- 
tants of  the   island  of  Walcheren   able  to  pursue   their  ordinary  avocations. 
Biometric  attempts  have  been  made  to  discover  correlations  between  physical 
and  mental  traits  and  disease  by  comparing  individuals  of  the  same  race,  but  if  we 
compare  individuals  of  different  races,  in  whom  contrasts  in  resisting  power,  colour, 
and  the  like  are  so  much  more  marked  as  to  be  easily  observable,  we  find  no 
such  correlations. 


262  THE  PRESENT  EVOLUTION  OF  MAN 

with  many  others  which  have  suffered  less  or  not  at  all.  If  disease 
produces  any  germinal  change,  then,  no  matter  how  small  and  im- 
perceptible the  difference  between  one  generation  and  the  next,  or 
how  confused  with  spontaneous  variations,  the  constant  accentua- 
tion of  the  alteration  during  hundreds,  perhaps  thousands,  of 
generations,  must  make  it  at  last  manifest  and  unmistakable. 
The  multitude  of  races  and  their  diseases  is  so  great  that  we  are 
able  to  make  endless  comparisons  and  so  reduce  the  chance  of 
error  to  a  minimum.  The  materials  are  so  familiar  that  every  man 
may  verify  them  for  himself;  whereby  that  grave  source  of  error 
and  doubt,  the  '  personal  equation '  of  the  observer,  is  eliminated. 

434.  Manifestly,  we  are  dealing  now  with  a  problem  of  the  first 
importance,  the  question  of  the  causation  of  variations,  which, 
both  from  a  theoretical  and  a  practical  standpoint,  is  the  central 
problem    of    heredity.      All    theories   of    racial    adaptation    and 
degeneration,  of  the  influence  of  environment,  of  likenesses  and 
differences  between  parents  and  offspring,  of  plant  and  animal 
breeding,  of  far-reaching  social  effort  depend  on  it.    Disease  affords 
material  for  solving  the  problem  more  conclusively  than  anything 
else  to  be  met  with  in  nature.     The  reader  must,  therefore,  consider 
carefully  what  theory  of  the  causation  of  variations  fits  in  with  the 
known  changes  undergone  by  races  that  have  been  in  contact  with 
disease.     In  other  words,  he  must  make  a  rigorous  deductive  infer- 
ence  of  consequences,    and    then   carefully   compare   these    con- 
sequences to  reality. 

435.  The  facts  are  decisive.     Nearly  all  human  races  have  been 
exposed  to  disease  for  thousands  of  years,  and  in  no  instance  is 
there  to  be  found  an  iota  of  evidence  that  any  race  has,  as  a  con- 
sequence, become   degenerate,  or  that  any  race  has  transmuted 
acquired   into  inborn   immunity.     On   the   contrary,  not   only  is 
every  race  resistant  to  every  prevalent  and  lethal  disease  precisely 
in  proportion  to  its  past  experience  of  it,  but  the  resisting  power  is 
such  that  it   can   have   been    evolved   only  through   the   Natural 
Selection  of  the  spontaneous  variations  of  a  germ-plasm  that  was 
insusceptible  to  the  direct  action  of  the  environment,  and  did  not 
transmute  acquirements  into  innate  characters.     Without  excep- 
tion, those  races  which  have  been  exposed  to  diseases  (e.g.  tuber- 
culosis),   against   which    immunity   cannot    be    acquired    by   the 
individual,  have  tended  to  become,  not    enfeebled,   but  innately 
capable  of  resisting   infection  ;    whereas,   races  which  have  been 
exposed   to   diseases   against  which   immunity  may  be  acquired 
(e.g.    measles),   have    evolved    nothing    other   than   an    increased 


ACCLIMATIZATION  263 

capacity  of  making  the  acquirement,  of  recovering  from  infection. 
On  the  other  hand,  races  that  have  been  exposed  to  non-lethal 
diseases  (e.g.  chicken-pox),  are  neither  more  nor  less  resistant, 
neither  more  nor  less  degenerate  than  races  that  have  had  no 
previous  experience  of  them.  Apparently  they  are  in  no  way 
changed.  The  sufferings  of  races  have  not  altered  them  at  all. 
Only  the  elimination  of  the  un fittest  has  altered  them. 

436.  Clearly  both  the  Lamarckian  doctrine  of  the  transmission 
of  acquirements  and  the  doctrine  that   variations   are   normally 
caused  by  the  direct  action  of  the  environment  on  the  germ-plasm 
are  erroneous.     The  theory  that  the  mass  of  variations  are  spon- 
taneous is  just  as  clearly  correct.     Only  in  that  case  can  Natural 
Selection,  the  actuality  of  which  as  regards  disease  is  obvious  to 
every  observer,  have  produced  the  particular  racial  changes  that 
have  resulted.     We  constantly  speak  of  the  acclimatization  of  an 
individual   or  a  race.     As  applied  to  individuals,  the  term  is  a 
synonym  for  use-acquirement,   for  protective  development,  for  a 
becoming  accustomed   or  habituated   to    the    new   conditions — a 
habitation  which  may  be  '  active '  (i.e.  due  to  recovery  from  actual 
disease),  or  '  passive  '  (i.e.  due  to  experience  of  microbes  and  toxins 
in  doses  too  small  to  cause  disease).     As  applied  to  races,  it  is  a 
synonym  for  protective  evolution,  which,  in  the  case  of  diseases 
against  which  immunity  cannot  be  acquired,  implies  the  increase  of 
a  power  of  resisting  infection^  and  in  the  case  of  diseases  against 
which  immunity  can  be  acquired,  implies  the  increase  of  a  power 
of  recovering  from  infection  and  resisting  it  subsequently.     When 
we  talk  of  the  deadly  climate  of  West  Africa  and  the  healthy  climate 
of  England,  we  think  only  of  ourselves.     Not  less  deadly  to  the 
African  negro,  to  whom  the  West  Coast  is  healthy,  is  the  climate 
of  London  with  its  prevalent  tuberculosis.     To  the  Polynesian  or 
Red  Indian,  whose  race  has  had  even  less  experience  of  this  disease, 
a  residence  in  any  one  of  our  great  cities  is  usually  equivalent  to  a 
sentence  of  death. 

437.  All  educated  men  know  more  or  less  clearly  that  every 
race  that  has  long  dwelt   in  any  environment   is  especially  well 
adapted   to   the   conditions   of  that    environment,   including    its 
diseases.     Medical  men  share  this  knowledge.     But  most  doctors 
believe  atsothat  races  tend  to  deteriorate  when  exposed  to  injurious 
conditions.     The  two  beliefs  are  utterly  incompatible,  and  afford  a 
good  example  of  the  confusion  of  thought  that  arises  when  the 
duty  of  making  a  rigorous  deductive  inference  of  consequences 
is   neglected.     The  latter   belief  (that   variations   are   commonly 


264  THE  PRESENT  EVOLUTION  OF  MAN 

caused  by  the  direct  action  of  the  environment)  is  based  in  part, 
apparently,  on  a  tradition  ultimately  derived  from  popular  notions 
and  first  acquired  by  us  all  in  the  nursery,  and  in  part  on  experi- 
ments and  statistics  which  as  a  rule  have  no  bearing  on  the  point 
at  issue.  The  problem,  as  we  have  already  noted,  is  not  whether 
it  is  possible  to  devise  conditions  in  which  the  germ-plasm  is 
injured  beyond  recovery,  but  not  destroyed,  but  whether  under 
conditions  more  or  less  normal  to  the  race  variations  are  commonly 
caused  by  the  direct  influence  of  the  environment.1  Disease, 
which  at  one  time  or  another  affects  practically  every  individual 
in  England  and  Africa,  has  for  thousands  of  years  been  almost 
as  normal  an  occurrence  as  birth  itself. 

438.  The  experiments  on  which  medical  men  rely  are  such  as 
are  afforded  by  Clayton's  beans,2  transplanted  Alpine  plants, 
Fere's  alcoholized  eggs,3  and  the  like.  The  experiments  they 
ignore  are  those  of  nature  which  every  day's  professional  work 
brings  under  their  notice,  but  over  which  hangs  the  veil  of  famili- 
arity. The  statistics  they  rely  on  are  such  as  alienists  collect.4 

1See  §  1 60.  2See  §§  134,  156. 

3  I  think  it  would  puzzle  anyone  who  tries  to  think  clearly  to  explain  how 
Fere's  perpetually  quoted  experiments  bear  on  the  problem  of  the  causation  of 
variations.  Fere  exposed  eggs  to  the  vapour  of  alcohol  and  got  some  remarkably 
miserable  chickens.  This  indicates  that  alcohol  is  bad  for  developing  chickens. 
It  does  not  indicate  that  the  ill-effects  are  germinal  and  therefore  '  innate  '  and 
'  transmissible  '  to  descendants — any  more  than  a  plucked  chicken  indicates  that 
the  effects  of  plucking  are  '  inheritable.'  Fere  should  have  bred  from  his  de- 
debauched  chickens.  The  attitude  of  some  medical  men,  who  are  interested  in 
philanthropy,  especially  temperance  reform,  and  who  have  been  accustomed  to 
insist  on  the  '  degeneracy  '  which  results  from  insanitation  and  drink,  is  instructive 
from  the  point  of  view  of  scientific  education  (see  §  1 16,  footnote).  The  statement 
that  ill-conditions  cause  protective  evolution,  not  racial  deterioration,  is  often 
declared  by  them  to  be  too  '  philosophical '  or  '  academic  '  or  '  logical.'  '  Honest 
facts  '  are  demanded.  It  is  hard  to  say  what  is  meant  exactly — possibly  nothing 
more  than  that  the  masses  of  fact  on  which  the  statement  is  founded  are  large 
and  complex,  and  the  thinking  necessary  before  the  relations  can  be  ascertained 
somewhat  difficult.  The  fact  that  diseases  cause  evolution,  not  deterioration,  if 
not  honest,  is  at  least  indisputable.  I  imagine  by  honest  is  meant  experimental. 
The  statement  that  "  we  know  very  little  about  heredity  "  has  no  doubt  very 
often  an  element  of  truth  ;  but  the  version  that  "  very  little  is  known  about 
heredity  "  is  distinctly  inaccurate.  Sometimes  it  is  said  that  "  the  proposition 
that  germ-cells  are  inviolable  is  sheer  nonsense.  They  are  just  as  liable  to  injury 
as  other  cells,  and  we  have  daily  experience  that  somatic  cells  may  be  injured." 
But  no  one  has  maintained  that  germ-cells  are  inviolable.  It  has  only  been 
maintained  that  all  kinds  of  cells,  including  the  germ-cells  of  all  species,  have 
been  so  dealt  with  by  Natural  Selection  that  they  hold  to  their  hereditary 
tendencies  almost  as  firmly  as  they  hold  to  life. 

*See§§  131,  135. 


THE  MIGRATIONS  OF  NEGROES  265 

The  statistics  unused  are  those  published  by  Departments  of 
Public  Health,  which,  especially  in  the  conquests  and  colonies  of 
Europeans,  show  clearly  the  real  effects  which  have  flowed  from 
racial  experience  of  disease. 

439.  It  is  hardly  necessary  to  quote  evidence  that  races  are 
resistant  to  diseases  in  proportion  to  their  past  experience  of 
them.1  The  evolution  of  negroes  against  tuberculosis,  however,  is 
so  very  illuminating  and  typical  that  it  is  worth  while  to  devote  a 
paragraph  to  it.  There  are  no  accounts  of  negro  conquests  outside 
the  limits  of  Africa,  but  from  very  ancient  times  a  constant  stream, 
of  slaves  has  passed  to  Southern  Europe  and  Asia,  where  they 
have  been  employed  mainly  in  domestic  service,  and  in  more 
recent  times  to  America,  where  their  principal  occupation  has  been 
agriculture.  The  invasion  of  Asia  has  continued  to  our  own  day  ; 
but,  notwithstanding  the  great  antiquity  and  volume  of  the  stream, 
one  may  search  from  Spain  to  the  Malay  Peninsula,  and,  except  in 
recent  importations,  find  no  trace  of  a  negro  ancestry.  Yet  slaves 
like  cattle  are  valuable  property,  more  cheaply  bred  than  imported. 
In  Eastern  countries  they  have  often  been  kindly  treated,  and 
many  have  achieved  wealth  and  power.  Yet  they  all  perished  in 
a  few  generations,  the  elimination  of  the  unfit  being  so  stringent 
as  to  cause  extinction,  not  evolution.  A  permanent  colony  of 
native  Africans  in  the  midst  of  an  ancient  tuberculosis-infested 
civilization  is  impossible.  The  fate  of  negro  migration  into 
America  has  been  different.  The  race  had  undergone  some 
evolution  against  tuberculosis  in  Africa,  and  therefore  was  more 
resistant  than  the  vanishing  aborigines.  In  its  new  home, 
employed  in  agriculture  in  a  hot  climate  where  white  men  and 
tubercle  bacilli,  also  recent  importations,  were  yet  few  in  number,  it 
was  placed  under  the  best  conditions  possible.  Gradually,  as  the 
stringency  of  selection  waxed,  it  evolved  increasing  resisting  power. 
To-day  the  descendants  of  the  migrants  have  undergone  such  an 
extent  of  protective  evolution  that  they  are  able  to  dwell  even  in 
North  American  and  European  cities,  though  it  is  still  said  of 
them  that  "every  other  adult  negro  dies  of  consumption." 

1  The  reader  who  requires  evidence  will  find  it  in  convincing  quantities  in  my 
work,  The  Principles  of  Heredity,  chapter  xi. 


CHAPTER  XIV 
EPIDEMIC  AND  ENDEMIC  DISEASE 

The  conditions  of  parasitic  life — Probably  every  disease  originated  from  a 
single  centre — No  new  diseases  are  known — Disease  in  ancient  and  modern  times 
— Contagious  diseases — Insect-borne  diseases — Air-borne  diseases — Water-borne 
diseases — Earth-borne  diseases — The  antiquity  of  diseases — Pestilence — The 
invasion  of  the  Western  Hemisphere  by  disease — Diseases  as  empire-builders. 


w 


440.  "^~^[  7"^  mav  safety  assume  that  the  micro-organisms  of 
disease  evolved  from  saprophytic  forms  of  life,  the 
only  alternative  being  the  impossible  hypothesis 
that  these  highly  specialized  types  arose  by  spontaneous  generation 
after  the  evolution  of  the  higher  animals  and  plants.  Precisely 
how  the  passage  from  a  saprophytic  to  a  parasitic  mode  of  life 
occurred  is  a  matter  of  conjecture.  We  know  only  that  there  is  per- 
petual war  in  nature,  and  that  the  bodies  of  the  higher  animal  types 
contain  nutritious  material  of  which  the  lower  types  must  always 
have  tended  to  avail  themselves.  From  the  beginning,  therefore, 
there  must  have  been  some  sort  of  a  struggle.  The  evolution  of 
the  parasite  had  two  concurrent  phases.  First,  the  saprophytic 
species  must  have  become  capable  of  persisting  for  a  longer  or 
shorter  period  in  living  bodies  in  spite  of  their  defences.  Second, 
it  must  have  evolved  means  of  passing  from  infected  to  healthy 
but  susceptible  individuals.  Some  saprophytic  species  are  very 
virulent,  for  example  those  of  putrefaction.  Apparently  the 
toxins  they  manufacture  are  either  digestive  ferments  or  means  of 
offence  or  defence  against  other  lowly  organisms.  Under  favour- 
able circumstances  they  readily  adopt  a  parasitic  mode  of  life, 
causing  disease ;  but,  since  they  are  unable  to  pass  easily  from  one 
individual  to  another,  they  cannot  maintain  themselves  as  parasites. 
Thus,  also,  the  microbes  of  vaccinia  are  unable  to  persist  unless 
artificially  propagated.  The  main  difficulty  to  be  overcome  by  an 
evolving  microbic  species,  then,  is  not  the  development  of  virulence, 
but  the  evolution  of  faculties  for  passing  from  one  individual  to 
another.  Possibly  each  species  of  pathogenic  organism  first  estab- 
lished itself  as  a  regular  parasite  during  times  when  hardship,  famine, 


THE  ORIGINS  OF  MICROBIC  DISEASES  267 

or  other  causes  had  lowered  the  resisting  power  of  a  community  of 
its  present  hosts. 

441.  The  microbes  of  the  different  diseases  differ  so  sharply  in 
the  effects  they  produce,  in  their  methods  of  protecting  themselves 
when  in  the  body,  and  in  their  modes  of  passage  from  one  in- 
dividual to  another,  that  it  seems  more  probable  that  each  patho- 
genic species  was  derived  direct  from  a  separate  saprophytic  type 
than  that  any  two  species  were  derived  from  a  common  parasitic 
stock — an  ancient  disease  ancestral  to  two  modern  diseases.  Very 
possibly  the  air-borne  species  arose  from  saprophytic  types  that 
were  originally  air-borne,  the  water-borne  species  from  water-borne 
saprophytes,  and  the  contagious  types  from  saprophytes  that 
normally  and  harmlessly  inhabited  cavities  of  the  body,  and  so  on. 
Again,  since  the  constant  tendency  in  nature  is  towards  differentia- 
tion, not  approximation,  in  type,  since  the  microbes  of  disease  are 
highly  specialized,  and  since  the  passage  from  saprophytic  to 
parasitic  ways  of  life  is  very  difficult,  whereas,  when  once  the 
parasitic  habit  is  established,  the  passage  from  one  host  to  another, 
and  so  from  one  country  to  another,  is  comparatively  easy,  it  seems 
probable  that  no  disease  had  multiple  origins  in  different  parts  of 
the  world,  but  that  every  disease  spread  from  a  single  centre.1 
However,  as  to  all  this  we  have  no  direct  evidence  on  which  to  base 
speculation. 

1  At  least  we  must  consider  it  improbable  that  diseases  had  multiple  origins 
if  we  accept  the  selectionist  theory  of  evolution.  Doubtless,  however,  supporters 
of  the  mutation  theory,  who  insist  that  the  same  mutation  tends  constantly  to 
occur  in  the  same  species,  would  hold  a  contrary  opinion.  But  probably  recur- 
rent mutations  are  in  most,  if  not  all  cases,  reversions  (see  footnote,  §  297). 
None  of  them  have  been  known  to  be  adaptive,  and  a  mutation  which  adapted 
a  saprophytic  species  in  all  its  structures  to  a  parasitic  mode  of  life  would  be  a 
very  wonderful  thing.  It  would  involve,  not  only  the  sudden  development  of 
great  virulence  and  all  that  that  implies,  including  a  capacity  to  resist  the  enzymes 
of  the  host,  but,  at  the  same  time,  a  power  and  a  tendency  to  pass  from  the 
infected  person  to  others  in  the  neighbourhood.  Moreover,  this  amazing  con- 
glomeration of  correlated  mutations  would  have  to  occur,  not  in  one  or  a  few 
microbes  but  simultaneously  in  thousands  ;  for  if  only  a  few  microbes  invade 
the  body  they  perish.  Disease  results  from  the  invasion  of  very  many  (see 
§  402).  Thus  the  microbes  of  vaccinia  are  unable  to  persist  naturally  because 
as  a  variety  they  lack  means  of  passing  from  one  host  to  another.  It  follows,  if 
evolution  is  by  mutation,  then  only  the  simultaneous  mutation  of  thousands  of 
vaccinia  or  other  microbes  could  render  them  independent  of  artificial  propagation. 
On  the  other  hand,  if  evolution  proceeds  by  the  selection  of  fluctuations,  a  passage 
through  a  few  weakly  (e.g.  non-resistant  or  starving)  persons  might  create  the 
necessary  virulence  (see  §  400).  It  must  be  borne  in  mind  that  it  has  been  ex- 
perimentally demonstrated  that  microbes  gain  in  virulence  only  slowly  after  the 
passage  of  many  generations,  and  unless  greatly  injured,  as  by  heat,  lose  their 
virulence  as  slowly. 


268  EPIDEMIC  AND  ENDEMIC  DISEASE 

442.  Somewhat  better  than  mere  guessing  is  the  assumption 
that  mankind,  under  the   influence  of  constant   persecution,  has 
gradually  grown  more  resistant,  not  only  to  particular  diseases,  but 
to  microbic  infection  in  general.     Owing  to  the  increase  of  popu- 
lation, and  to  the  crowded,  insanitary,  wretched  conditions  under 
which  many  communities  live,  the  facilities  for  the  evolution  of 
parasitic  types  are  now  greater  than  ever  they  were.     Yet,  though 
we  have  the  whole  world  under  survey,  we  never  hear  of  a  new 
disease.      The  so-called  new  diseases  are  merely  maladies  newly 
observed    in    their   ancient   habitats,    or   complaints   which   have 
invaded  fresh  territories.     Presumably,  therefore,  the  alteration  of 
saprophytes  into  parasites  (i.e.  the  evolution  of  a  new  disease)  is 
now  a  more  difficult  and  unlikely  occurrence  than  it  was  anciently. 
This  conjecture  (that  mankind  has  evolved  against  microbic  infec- 
tion in  general  as  well  as  against  particular  diseases)  is  confirmed 
by  the  fact  that  children,  who  recapitulate  the  life-history,  are,  as 
a  rule,  less  resistant  to  microbic  disease  than  adults,  even  when  the 
disease  is  one  of  which  the  race  has  had  little  or  no  experience. 
For  example,  English  children  succumb  much  more  readily  than 
older  persons  of  their  own  race  to  malaria  and  dysentery.     It 
must  be  remembered,  however,  that  since  variations  occur  during 
all  stages  of  development,  the  race  evolves  in  the  stage  of  develop- 
ment reached  by  the  child  as  well  as  in  the  adult  stage.     On  this 
account  African  and  Indian  children  succumb  much  less  readily 
to   malaria  and   dysentery  than   English  children,  though  more 
readily  than  adults  of  their  own  race.1 

443.  On  the  other  hand,  we  have  no  certain  evidence  that  any 
disease  has  ever  completely  died  out.     The  chances  are  all  against 
such  occurrences  in  the  past.     When  once  established  as  parasites, 
the  microbes,  owing  to  the  continual  growth  of  human  populations, 
found  a  constantly  augmented  food-supply  as  well  as  increased 
opportunities    of    reaching   fresh   fields    of   conquest.      Sanitary 
science  is  still  in  its  infancy,  and  as  yet  has  accomplished  compara- 
tively little.    Under  skilled  direction  it  has  done  something  towards 
diminishing  earth-,  water-,  and  insect-borne  diseases.     Tuberculosis, 
enteric  and  yellow  fever,  and  malaria  have  diminished  somewhat 
in  a  few  parts  of  the  world.     Leprosy  has  disappeared  from  some 
countries.     But  air-borne  diseases,  which  are  propagated  through 
a  medium  the  flow  of  which  is  too  swift  and  the  volume  too  vast 
for  control,  are  as  common  as  ever.     Almost  every  child  acquires 
measles,    whooping-cough,    chicken-pox,    mumps,  common    cold, 

1  See  §417. 


THE  ANTIQUITY  OF  DISEASES  269 

bronchitis,  and,  in  its  modified  form,  smallpox.     All  are  more  or 
less  exposed  to  scarlet  fever,  diphtheria,  pneumonia,  and  influenza. 

444.  We  have  historical    evidence   of  the   antiquity  of  many 
diseases.     Leprosy  is  mentioned  in  the  Book  of  Exodus  as  pre- 
valent in  Egypt.     By  other  accounts  it  was  prevalent  in  India, 
China,  and  Japan  about  the  same  time.     Contagious  diseases  (e.g. 
syphilis)  were  well  known  to  the  Greek  and  Roman  writers.1     We 
have  few  accounts  of  them  from  the  Middle  Ages,  when  physicians 
regarded  their  treatment  as  degrading  to  professional  dignity ;  but 
at  the  Renaissance  the  '  great  pox '  was  a  terrible  scourge.     "  A 
pox  on  you  "  was  a  common  Elizabethan  malediction.     "  Consump- 
tion of  the  lungs  may  be  traced  with  certainty  in  the  writings  of 
every  period  as  far  back  as  the  earliest  attempts  of  the  ancient 
world  to  deal  with  medicine  according  to  a  method."  2     Granting 
that  diseases  had  not  multiple  origins,  their  wide  prevalence  in  the 
ancient  world,  when  communities  dwelt  in   far  greater  isolation 
than  at  present,  argues  extreme  antiquity. 

445.  It  seems  probable  that  both  man  and  his  diseases  arose 
in  the  Eastern  Hemisphere,  where  "  behind  dim  empires  ghosts  of 
dimmer    empires    loom."     Still    more    ancient   than    the    oldest 
empires  are  the  traces  of  the  early  agriculturists,  who  in  turn  were 
preceded  by  the  hunters  and  cave-men  of  the  long  Stone  Ages. 
Amongst  savages  of  the  lowest  types  the  problem  of  the  food- 
supply  is  always  acute.     Population,   as  till  lately  amongst  the 
natives  of  Australia,  tends  always  to  exceed  the  available  supply 
and  is  limited  by  recurrent  famine.     Man  is  naturally  a  gregarious 
animal,  delighting  in  large  communities,  but  the  difficulty  of  pro- 
curing sufficient  food  forces  a  race  of  hunters,  not  only  to  scatter, 
but   to   assert  rights   of  ownership   over  large  areas  of  country, 
intrusion  into  which  by  strangers   is  strongly   resented.     Hence 
tribal  jealousy,  perpetual  warfare,  and  frequently  an  isolation  so 
profound  and  stringent  that  the  inhabitants  of  near  valleys  may  be 
of  distinct  types  and    speak  a   language  unintelligible  to   their 
neighbours.     Civilization  implies  a  dense  and  settled  community, 
which  in  turn  implies  a  more  abundant  and  secure  supply  of  food, 
and  that,  again,  implies  comparative  peace,  combined  with  regular 
communications  over  great  areas  of  land  and  even  of  water,  where- 
by the   deficiencies   of  one   part   are    supplied   from    the  super- 

1  Hirsch's  Handbook  of  Geographical  and  Historical  Pathology,  vol.   ii.  p.  2 
(New  Sydenham  Society).     The  notion  is  general  that  the  venereal  diseases  were 
imported  from  America,  but  this  would  appear  to  be  an  error. 

2  Op.  cit.,  vol.  iii.  p.  170- 


270  EPIDEMIC  AND  ENDEMIC  DISEASE 

abundance  of  others.  Our  many  and  vast  English  cities  are 
possible  only  because  our  peace  is  more  profound  and  our  means 
of  communication  more  perfect  than  ever  before  in  the  history  of 
man.  On  our  tables  may  be  found  fruit  and  spices  from  the 
tropics,  wheat  from  Canada,  Australia,  and  Russia,  mutton  from 
New  Zealand,  beef  from  the  Argentine,  rice  from  India  and  China, 
bacon  from  the  United  States,  and  fish  from  half  the  world. 
To-day  we  may  eat  cheese  or  drink  wine  that  has  been  stored  for 
years.  So  widely  do  we  travel  that  there  is  on  earth  scarcely  a 
distinct  language  but  some  Englishman  is  able  to  express  himself 
in  it. 

446.  The  pressure  of  population,  therefore,  is  usually  greatest 
amongst  the  lowest  types  of  mankind,  and  this   results,   not  in 
intercommunication,  but  in  isolation  ;  in  wars  the  object  of  which 
is  extermination  not  subjugation  ;  in  a  search  for   food,  not  for 
slaves,  whom  a  stone  or  pointed  stick  would  arm  as  well  as  their 
masters.     Doubtless  it  was  during  this  time  of  great  pressure  and 
desperate   struggle  that   man,    spreading  slowly  from  a  common 
centre,    populated    the    Eastern    and     ultimately    the    Western 
Hemisphere. 

447.  The  era  of  the  early  hunters,    who   subsisted  solely  on 
wild  animals  and  vegetables,  was  followed  by  that  of  the  primitive 
shepherds  and  husbandmen,  who  made  provision,  not  only  for  the 
immediate  present  by  hunting,  but  for  the  future  by  labour.     The 
supply  of  food  became  more  abundant  and  secure.     Property  in 
land  tended  to  become  personal  instead  of  tribal.     Men  began  to 
gather   for  mutual  protection   into   communities,   which   differed 
from  one  another  in  their  stored  productions.     Barter,  and  there- 
fore intercommunication,  become  more  general  and   widespread. 
Since  the  labour  of  a  man  now  produced  more  food  than  sufficed 
for  his  own  existence,  warfare  underwent  gradual  change.     The 
conquerors  sought  slaves  and  tributaries  rather  than  mere  elbow- 
room.     They  subjugated  rather  than  exterminated  their  enemies. 
Population   increased    immensely,  and   with  it   the   microbes   of 
disease,  which,  spreadingfrom  their  centre  of  origin,  ranged  to  and 
fro  with  travellers  and  raiders. 

448.  The  microbes  of  contagious  diseases  pass  directly  from 
one  individual  to  another.     The  living  body  furnishes  their  entire 
environment,  and,  therefore,  they  are  able  to  exist  in  all  climates 
and  under  all  conditions.     The  long  duration  in  the  individual  of 
syphilis,  the  chief  of  them,  makes  itespecially  capable  of  infecting  and 
maintaining  its  hold  on  new  communities.    But  the  method  by  which 


THE  MIGRATIONS  OF  MALARIA  271 

contagious  maladies  pass  from  one  individual  to  another  renders 
their  diffusion  through  a  population  comparatively  slow.  They 
are  endemic  from  the  first.  They  rarely  cause  great  epidemics ; 
but,  once  established,  are  never  again  absent  from  their  new  habitat. 

449.  The  microbes  of  all  other  diseases  alternate  between  the 
human  body  and  the  world  outside,  in  which,  on  the  way  to  fresh 
'  hosts/  they  pass  a  longer  or  a  shorter  time.  They  are  depen- 
dent, therefore,  to  a  greater  or  lesser  extent  on  this  outer  environ- 
ment. The  insect-borne  maladies  are  found  only  in  localities 
where  the  insect  host  is  able  to  maintain  existence.  Malaria  was 
once  common  in  England,  but  the  conditions  became  unfavourable 
to  the  mosquito,  and  the  disease  disappeared.  Though  many 
infected  people  from  the  tropics  land  on  our  shores,  it  cannot  re- 
establish itself.  In  historic  times  it  is  said  to  have  invaded 
Greece  and  Italy,  and  by  some  medical  writers  is  supposed  to 
have  contributed  to  the  downfall  of  the  classic  empires.  In  more 
modern  times  it  invaded  Mauritius.  The  fact  that  before  the 
historical  era  malaria  had  spread  to  most  parts  of  the  globe  where 
its  intermediate  host,  the  Anopheles  mosquito,  is  capable  of  per- 
sisting, is  evidence  of  its  vast  antiquity.  Of  all  the  host  of 
maladies  which  now  infest  the  Western  Hemisphere  it  is  apparently 
the  only  one  of  any  importance  which  was  not  introduced  by 
Columbus  and  his  successors.  Possibly  it  is  the  most  ancient  of 
all  human  diseases.  The  path  by  which  it  journeyed  to  America 
is  quite  unknown.  Under  present  conditions  of  climate  it  can 
hardly  have  travelled  by  the  Arctic  circle.  Before  the  era  of 
European  discovery  man  had  crossed  the  Pacific,  all  the  large 
islands  of  which  are  thickly  populated.  But,  except  near 
Asia,  malaria  is  unknown  in  them.  The  difficulties  of  crossing  the 
practically  uubroken  expanse  of  the  Atlantic  are  obvious.  The 
antiquity  of  the  disease  is  evidently  so  great  that  the  surmise  that 
it  may  have  reached  America  during  a  warm  inter-glacial  period  is 
perhaps  not  altogether  extravagant 

450.  Plague,  sleeping  sickness,  and  yellow  fever  are  other  very 
important  insect-borne  maladies.  Plague  is  a  disease  of  rats,  the 
intermediate  host  being  a  species  of  flea  which  is  parasitic  on  these 
animals,  but  which  will  on  occasion  attack  human  beings.  During 
an  epidemic  the  rats  tend  to  be  exterminated  and  the  disease  to 
die  out.  It  is  endemic  in  India,  but  several  great  pandemics  in 
which  it  spread  widely  are  recorded  in  history.  It  was  known  in 
Europe  before  the  Christian  era.1  In  the  sixth  century  after 
1  Hksch,  vol.  i.  p.  494. 


272  EPIDEMIC  AND  ENDEMIC  DISEASE 

Christ  it  "  spread  over  the  whole  Roman  Empire  of  the  East  and 
West  and  even  far  beyond  the  limits  of  the  empire ;  .  .  .  and 
wrought  the  most  frightful  devastation  wherever  it  appeared ;  .  .  . 
it  depopulated  towns,  turned  the  country  into  a  desert,  and  made 
the  habitations  of  men  to  become  the  haunts  of  wild  beasts."1 
Another  great  pandemic,  "  known  everywhere  under  the  name  of 
the  Black  Death  as  one  of  the  great  events  in  the  world's  history," 
"  reached  over  the  whole  of  the  known  world  "  and  destroyed  a 
third  or  a  quarter  of  the  inhabitants  of  Europe.  The  Great  Plague 
of  London  furnishes  an  additional  example. 

451.  Yellow  fever,  like  malaria,  has  the  mosquito  for  its  inter- 
mediate host.     Its  original  habitat  appears  to  have  been  the  West 
Coast  of  Africa,  but  it  is  now  endemic  in  the  tropical  parts  of 
Eastern  America.     Till  very  recently  sleeping  sickness  appears  to 
have  been  confined  to  the  West  Coast  of  Africa.     It  was  often 
carried  by  slaves  to  Brazil  and  the  West  Indies,  where,  however,  in 
the   absence    of    its    intermediate   host    the    tsetse   fly   (Glossina 
palpalis\  it  did  not  spread.     The  infected  slaves  were  supposed 
to  be  suffering  from  nostalgia  or  home-sickness.2     Owing  to  the 
improvements  of  communications  consequent  on  European  con- 
quest, it  has  spread  very  widely  and  has  now  almost  reached  the 
East  Coast  near  Zanzibar,  where  it  is  likely  to  prove  a  scourge  as 
terrible   as   it   is   already   in    Uganda.     Doubtless  the   tsetse  fly 
preceded  the  disease  in  Central  Africa,  but  did  no  great  harm  till 
infected  human  beings  arrived.     The  insect-borne  diseases  are  the 
only  complaints  which,  on  the  whole,  afflict  sparse  populations 
more  than  they  do  denser  communities  of  men. 

452.  Air-borne  maladies  are  immensely  infective  but  of  short 
duration  in  the  individual.     After  a  brief  illness  the  sufferer  dies  or 
acquires  an  immunity  which  may  or  may  not  be  permanent.     Con- 
sequently, in  small  and  isolated  communities,  they  can  occur  only 
in  epidemic  form,  at  any  rate  when  the  immunity  they  confer  is  at 
all  lasting.     Owing  to  the  large  number  of  susceptible  persons, 
such  a  disease,  when  it  reaches  a  new  country,  spreads  like  fire. 
If  it  has  long  been  absent,  it  strikes  down  the  whole  population. 
So  many  are  infected,  so  abundant  do  the  microbes  become,  that 
no  one  escapes  the  chance  of  infection.     As  a  consequence,  the 
food-supply  of  the  microbes  is  swiftly  exhausted,  and  the  malady 
disappears  till  re-introduced  from  foreign  sources.     On  the  other 

1  Hirsch,  vol.  i.  pp.  495-6. 

2  The  Kingdom  of  Man,  by  Sir  E.  Ray  Lankester,  p.  159  (London  :  Constable 
&  Co.,  1907). 


EPIDEMIC  AND  ENDEMIC  DISEASE  273 

hand,  when  a  community  is  large,  and  especially  when  it  enjoys 
constant  intercourse  with  other  considerable  centres  of  population 
air-borne  disease  prevails  in  endemic  form,  mild  exacerbations  of 
which  are  termed  epidemics.  Nearly  every  one  suffers  during 
youth.  The  non-resistant  perish,  the  resistant  acquire  immunity. 
New  births  supply  materials  sufficient  to  secure  the  persistence  of 
the  disease,  and  provide  for  the  so-called  epidemics;  but  the 
microbes  never  become  so  abundant  as  when  they  invade  a  new 
country  and  infect  the  whole  population.  Therefore  children  may 
not  be  infected  until  several  years  after  birth. 

453.  Disease,  when  endemic,   is    far   less   terrible   than    when 
epidemic.     In  the  former  case  the  sick  are  tended,  the  treatment 
is  understood,  and  the  business  of  the  community  is  not  impeded. 
In   the   latter,  so   great   may  be   the  number  of  adult   sufferers 
that  the  sick  receive  scant  attention,  and  so  considerable  the  dis- 
location  of  business   that    famine    may   follow.      Disease,  when 
endemic,  does  the  work  of  selection   much  more   'cleanly'  and 
thoroughly  than  when  epidemic.     Practically  every  non-resistant 
person  is  eliminated,  but  few  people  perish  from  neglect  or  starva- 
tion.    Epidemic  disease,  on  the  other  hand,  causes  the  death  of 
numbers  of  people  whose  powers  of  resistance  are  considerable, 
while  it  spares  during  its  intervals  of  absence  many  others  whose 
resisting  powers  are  low.     It  selects  in  a  much  less  discriminating 
fashion.1 

454.  Formerly  smallpox  was  endemic  in  Europe  in  the  same 
way  as  measles  is  to-day.     At  present  vaccinia  is  endemic.     The 
disappearance    of    smallpox   coincided    with   the    prevalence    of 
vaccinia.     A    considerable   portion    of  the  community,  including 
some  men  distinguished  in  science  or  of  great  intellectual  activity, 
insist  that  the  two  events  had  no  causal  connection,  and  therefore 
that  vaccinia  is  not  a  preventive  of  smallpox.     But,  if  they  are 
right,  it  is  difficult  to  conceive  what  can  have  banished  the  latter. 
It   cannot    have   been   sanitation,   for   smallpox   is   an   air-borne 

1  We  noted  that  sanitary  science  has  absolutely  no  control  over  air-borne 
disease.  In  England  it  is  customary  to  close  the  schools  during  an  epidemic  of 
measles,  chicken-pox,  mumps,  or  whooping-cough.  It  is  a  question  whether 
"  the  game  is  worth  the  candle,"  at  any  rate  as  a  preventive  measure.  Speaking 
practically,  every  susceptible  child — and  innately  unsusceptible  children  are 
rare — is  sure  to  acquire  the  disease  sooner  or  later.  The  danger  from  chicken- 
pox  and  mumps  is  negligible.  Measles  and  whooping-cough  are  more  dangerous 
to  infants  than  to  older  people,  but  not  appreciably  more  dangerous  to  school 
children  than  to  adults.  If  these  diseases  are  inevitable,  it  is  perhaps  better  that 
they  should  be  done  with  early  in  life,  when  time  is  less  valuable  and  the  incon- 
venience not  so  great  as  later. 
18 


274  EPIDEMIC  AND  ENDEMIC  DISEASE 

disease,  and  no  other  disease  of  this  kind  has  been  so  affected.  It 
cannot  have  been  isolation,  for,  if  vaccinia  is  no  protection,  almost 
the  whole  community  is  susceptible,  and  doctors  and  nurses  should 
contract  and  spread  the  disease.  Isolation  is  possible  only  when 
susceptible  individuals  are  comparatively  rare.  It  has  been  denied, 
even,  that  there  is  such  a  thing  as  acquired  immunity  against  any 
disease.  But  the  fact  that  the  microbes  of  acute  disease,  which  at 
first  swarm  in  an  infected  person,  disappear  within  a  definite  time, 
so  that  the  sufferer  no  longer  conveys  infection  after  recovery,  is 
decisive  proof.  The  fact  that  a  vaccinated  person  cannot  be  made 
to  contract  vaccinia  again  soon  after  recovery  is  proof  that  it  con- 
fers immunity  against  itself.  The  fact  that  he  can  be  successfully 
vaccinated  after  an  interval  of  years  is  proof  that  the  immunity  is 
not  perpetual.  The  fact  that  smallpox,  if  experimentally  trans- 
ferred to  the  calf,  becomes  cow-pox,  and  if  transferred  back  to  man 
becomes  vaccinia,  is  proof  that  the  latter  is  a  modified  form  of 
smallpox.  The  fact  that  recently  vaccinated  persons  are  able, 
with  almost  complete  safety,  to  nurse  people  ill  of  smallpox, 
whereas  unvaccinated  persons  are  almost  sure  to  contract  the 
disease,  is  proof  that  experience  of  the  attenuated  malady  affords 
protection  from  the  more  virulent  type.  The  fact  that  in  England 
most  people  who  contract  smallpox  have  been  vaccinated,  but  not 
recently,  is  proof  that  the  protection  afforded  by  vaccinia  is  only 
transient — so  transient,  owing  to  the  mildness  of  the  disease,  as  to 
be  midway  between  'acute'  and  'passive'  immunity.  Probably 
the  agitation  against  vaccination  would  never  have  arisen  in  this 
country  had  the  power  of  conferring  permanent  immunity  from 
smallpox  not  been  claimed  for  vaccinia  by  the  medical  men  of 
a  past  generation.  Reaction  followed  the  discovery  that  most 
sufferers  from  smallpox  had  undergone  vaccination.  The  public 
learns  very  slowly,  but  forgets  no  faster. 

455.  Water-borne  diseases  are  almost  as  infective  as  the  air- 
borne type.     They  prevail   as  epidemics  more  rarely  in  isolated 
communities,  but  as  such  are  not  uncommon  in  densely  populated 
centres.     The  microbes  are  very  dependent  on  the  environment 
outside  the  body  of  the   host,    therefore   they  are  less  able   to 
travel   than    air-borne   species,  and   seasonable  changes  may  for 
a    time    purify   the    water-supply,   even   where    they    are    most 
prevalent. 

456.  Earth-borne  diseases,  of  which  the  only  one  that  greatly 
affects  human  beings  is  tuberculosis,  are  always  endemic.     Direct 
sunlight  is  fatal  to  the  microbes  of  tuberculosis.     In  effect,  it  can- 


THE  DISEASES  OF  THE  LOWER  ANIMALS         275 

not  be  contracted  in  the  open  air.  Its  microbes  are  found  especi- 
ally in  such  dark,  ill-ventilated,  and  crowded  dwellings  as  are 
built  by  the  civilized  inhabitants  of  cold  and  temperate  regions. 
More  especially  it  affects  the  larger  towns  and  cities,  and  yet 
more  the  slums  of  these.  Beyond  all  other  complaints  it  is  the 
disease  of  civilization.  As  in  the  case  of  syphilis,  its  long 
duration  confers  considerable  powers  of  journeying  to  distant 
lands. 

457.  For  all  we  know  or  can  surmise  to  the  contrary,  distinctively 
human  contagious  and  insect-borne  maladies  may  have  prevailed 
during  the  early  Stone  Age.  Air-borne  maladies  can  hardly  have 
come  into  being  till  large  continental  tracts  had  been  relatively 
densely  peopled  by  hunters  and  nomads.  The  advent  of  water-  and 
earth-borne  diseases  must  have  occurred  later.  Their  existence 
implies  large  and  settled  populations.  In  the  one  case  the  water- 
supply,  and  in  the  other  stationary  dwellings  must  have  been 
constantly  used  and  infected.  Probably,  of  all  animals,  human 
beings  suffer  most,  or  at  least  from  the  greatest  number  of  microbic 
diseases.  More  than  any  other  animal,  man  now  dwells  in  large 
and  settled  communities,  between  which  there  is  constant  inter- 
course. Many  insect-borne  diseases  of  the  lower  animals,  however, 
are  known  to  be  endemic  in  certain  regions,  as  for  example  the 
Texas  fever  of  cattle,  which  is  carried  by  ticks,  and  the  fly-disease 
in  South  Africa,  which  is  borne  by  the  tsetse  fly.  Races  long 
afflicted  by  them  tend  to  evolve  resisting  power,  whilst,  as  in  the 
case  of  man,  immigrants  suffer  severely.  Air-borne  diseases,  such 
as  are  perhaps  the  rabbit  plague  of  Canada  and  rinderpest  which 
lately  more  than  decimated  the  herbivora  of  Africa,  are  the  causes 
of  the  great  murrains  or  pestilences  which  tend  to  appear  whenever 
animal  populations  become  dense.  The  distemper  of  dogs  appears 
to  have  become  endemic  amongst  the  large  and  settled  canine 
population  supported  by  man,  but  amongst  wild  animals  air-borne 
diseases  appear  always  to  be  epidemic.  Earth-borne  diseases  occur 
especially  amongst  browsing  animals,  which  acquire  them  through 
herbage  that  has  been  tainted  by  infected  individuals.  Probably 
the  disease  which  destroys  hive  -  bees  is  earth  -  borne.  Since 
recovery  within  definite  time  from  microbic  diseases  implies 
immunity,  and  since  the  vast  destruction  of  life  greatly  diminishes 
the  available  supply  of  nutriment  for  the  microbes,  epidemics 
amongst  lower  animals  are  usually  very  transient.  Probably  the 
starting-point  of  every  great  pandemic  of  earth-borne  disease  is 
some  area  where  the  animal  hosts,  having  undergone  evolution,  are 


276  EPIDEMIC  AND  ENDEMIC  DISEASE 

numerous  but  resistant,  and  where,  therefore,  the  disease  is  endemic. 
Rinderpest  is  said  always  to  start  from  Southern  or  Central  Asia.1 

458.  In  histories  and  poems  dealing  with  recent  times,  and  in 
the  works  of  modern  philosophers  or  people  who  attempt  to  found 
new  religious  sects,  we  rarely  meet  any  mention  of  endemic  diseases. 
These  are  accepted  as  part  of  the  normal  environment,  and  claim 
allusion  only  when  some  prominent  person  dies  of  a  'decline' 
(consumption)  or  the  like.     But  should  a  great  pestilence  occur,  it 
is  eagerly  noted,  described,  and  made  the  basis  of  endless  disserta- 
tions   and    exhortations.      Yet    among    modern    civilised    people 
endemic  disease  claims  by  far  the  greater  number  of  victims.     So 
also  ancient  records,  which  were  written  not  for  us  but  for  the 
contemporaries  of  the  writers,  tell  as  little  of  the  endemic  diseases 
prevalent  at  the  time  as  they  do  of  the  everyday  life  of  the  people, 
but  much  of  such  great  and  striking  disasters  as  epidemics  and 
wars.     We  may  be  sure,  however,  that  some  endemic  diseases,  for 
example  leprosy,  the  contagious  maladies,  and  malaria,  did  exist 
very  anciently. 

459.  A  notable  contrast  between  ancient  and  modern  times  is 
furnished   by  the  fact  that  pestilence  (i.e.  epidemic  disease)  was 

1  The  microbic  or  other  diseases  of  plants  and  lower  animals,  considered  from 
the  standpoint  of  the  student  of  evolution,  constitute  a  vast  subject  of  great 
intellectual  fascination  and  practical  importance,  which,  it  is  to  be  hoped,  some 
worker  with  more  time  and  knowledge  than  I  am  able  to  claim  will  investigate. 
Like  me,  he  will  find  his  materials  scattered  through  books  of  travel,  histories, 
and  technical  works,  but  will  have  to  surmount  even  greater  difficulties  than  I 
have  encountered  in  my  very  imperfect  and  fragmentary  study  of  human  disease. 
Many  profitable  industries  have  been  ruined  or  are  being  checked  in  various 
parts  of  the  world  by  plant  or  animal  disease.  Thus  Phylloxera  vastatrix  (a  species 
of  Aphides)  caused  great  damage  to  the  vines  of  France,  and  coffee-growing  had 
to  be  abandoned  in  Ceylon.  Pig  and  poultry  farming  on  a  large  scale  are  un- 
profitable, because  as  surely  as  many  animals  are  gathered  in  one  place  they  are 
swept  by  epidemic  disease.  Wild  animals  are  delicate  in  captivity,  mainly  because 
they  perish  of  microbic  diseases  against  which  domesticated  animals  have  under- 
gone some  evolution.  The  difficulties  of  the  farmer  illustrate  very  vividly  the 
dangers  which  beset  the  human  race  in  its  earliest  struggles  towards  settlement 
and  civilization.  Human  selective  breeding  is  at  present  outside  the  range 
of  practical  politics.  Selective  plant  and  animal  breeding  is  practised  all  the  world 
over  ;  but  I  am  not  aware  that  plants  and  animals,  especially  animals,  have  ever 
been  bred  to  any  considerable  extent  with  the  view  of  increasing  their  powers  of 
resisting  disease.  Some  horses  and  cattle,  for  example,  are  able  to  acquire  im- 
munity to  the  fly  disease  of  Africa.  Artificial  selection  achieves  results  much  more 
rapidly  than  Natural  Selection.  It  should  not  be  difficult  to  establish  a  resistant 
race  by  continued  breeding  from  animals  that  had  shown  themselves  capable  of 
recovery  from  infection.  Since  plants  are  almost  incapable  of  making  use- 
acquirements,  and  since  their  diseases  are  usually  caused  by  muticellular  organisms, 
only  '  inborn  '  immunity  could  be  evolved  amongst  them. 


ANCIENT  EPIDEMICS  277 

formerly  much  more  common  and  severe.  The  Great  Plague  of 
1666  was  the  last  very  destructive  epidemic  in  England,  but  it  was 
not  nearly  so  destructive  as  the  Black  Death,  which  occurred  some 
centuries  previously.  Both  these  pestilences  had  spread  from 
regions  in  the  East,  where  they  were  endemic,  where  the  inhabitants 
were  so  resistant  that  the  victims  were  comparatively  few,  and 
where  they  caused  no  more  comment  in  histories,  poems,  and  ex- 
hortations than  malaria  in  Africa  or  tuberculosis  in  England.  As 
has  always  been  customary,  preachers  in  Europe  attributed  them  to 
the  anger  of  the  Deity,  and  called  the  peoples  to  repentance  for 
sins  committed  against  this  or  that  religion,  and  to  a  more 
strenuous  support  of  this  or  that  sect.  Similarly,  while  no  great 
epidemic  of  our  domestic  diseases  is  recorded  in  history,  they  have 
occasioned  some  terrible  pestilences  amongst  peoples  to  whom  they 
were  previously  unknown,  to  whom  we  conveyed  them,  and  by  whom 
they  were  regarded  as  evidence  of  divine  or  diabolical  anger. 

460.  The  inference  is  irresistible  that  historians  are  mistaken 
when  they  attribute  ancient  epidemics  to  diseases  which,  owing  to 
war,  bad  sanitation,  or  similar  causes,  came  suddenly  into  being, 
but  have  since  died  out  of  the  world.  In  each  case  in  which  the 
accounts  are  sufficiently  ample  and  clear,  every  ancient  pest  may 
be  identified  with  an  air,  water,  or  insect-borne  malady  now,  as  theo, 
endemic  in  some  part  of  the  world,  whence  it  has  spread  periodically 
whenever  the  conditions,  such  as  a  hot,  dry  summer  and  much  inter- 
course between  neighbouring  nations,  have  become  favourable. 
Bad  sanitation  tends,  of  course,  to  render  a  strange  water-  or  insect- 
borne  disease  epidemic  when  once  it  has  arrived,  but,  other  things 
equal,  it  tends  also  to  perpetuate  it  afterwards  in  the  endemic 
form.  Yet,  though  sanitation  did  not  noticeably  improve,  the  Black 
Death,  the  Great  Plague,  and  other  exotic  diseases  retreated  to 
their  normal  habitats  in  India  or  farther  east.  Both  the  former 
were  evidently  the  same  bubonic  plague  which  is  now  ravaging 
India.  They  "  spent  their  force,"  they  disappeared  from  Europe 
because  they  were  epidemic — because  the  disease  became  so  pre- 
valent that  it  exhausted  its  nutrient  supply  of  susceptible  rats  or 
human  beings  so  effectually  that  it  could  not  persist.  Very 
modern  sanitation  has  rendered  its  return  to  Europe  difficult. 
Rats  are  less  numerous.  Probably  all  our  earth-  and  air-borne 
diseases,  which  are  much  better  able  to  travel  than  insect  and 
water-borne  complaints  and  therefore  sooner  become  permanently 
established,  were  endemic  amongst  our  ancestors  before  the  dawn 
of  established  history.  But  from  remote  periods,  from  myth  and 


278  EPIDEMIC  AND  ENDEMIC  DISEASE 

legend,  we  seem  to  gleam  dim  accounts  of  air-borne  pestilences. 
Thus  the  disaster  which  befell  the  Assyrian  host  before  Jerusalem 
and  that  which  afflicted  the  Greeks  before  Troy  had  that  appalling 
suddenness  which  characterizes  an  air-borne  epidemic  occurring  in 
a  population  entirely  susceptible. 

461.  To  sum  up,  human  microbic  diseases  seem  to  have  origi- 
nated  in  the  Eastern  Hemisphere,  which  has  long   been  thickly 
populated,  each  disease  from  a  single  centre,  whence  it  spread — 
facts  which  appear  to  be  confirmed  by  the  apparently  total  lack  of 
all  microbic  diseases,  except  malaria,  in  the  various  parts  of  the 
West   before   the   invasion   by  Europeans   and   their   subsequent 
establishment   there.     Earth-borne  and  contagious  diseases  must 
have  been  endemic  from  their  origins,  as  also  must  have  been  some 
insect-borne    maladies.      Doubtless    water-borne    diseases    early 
became  endemic  wherever  the  conditions,  including  a  dense  and 
settled  human  population,  were  favourable.     Air-borne  disease  was 
probably  epidemic  at  first,  passing  with  great  rapidity  and  fear- 
ful  results  from   one    region    to   another,   but   gradually  became 
endemic  in  all  thickly  populated  localities  that  were  in  frequent 
communication  with  surrounding  areas.     There  can  be  no  doubt 
that  all  our  familiar  maladies  were  rife  in  Europe  at  the  time  when 
Columbus  set  out  on  his  fateful  voyage,  and  initiated  the  greatest 
tragedy,  the  most  tremendous  event  in  human  history. 

462.  On  the   one  side  of  the  Atlantic  were  peoples  who  for 
thousands  or  tens  of  thousands  of  years  had  been  slowly  evolving 
resisting  power  against  a  multitude  of  maladies — peoples  whose 
increase  had  been  very  slow,  largely  because  of  the  numbers  of  the 
unfit  that  had  perished  from  disease,  maladies  that  had  gradually 
passed  from  the  epidemic  form  in  which  the   selection    of  their 
victims  was  haphazard  and  imperfect,  to  the  endemic  form,  when 
selection  was  more  thorough  and  clean.     These  Eastern  peoples 
now  dwelt  under  conditions  that  would  have  been  fatal  to  their 
remote  ancestors.     Their  civilization,  with  its  dense  communities 
and  constant  communication  between  distant  parts,  was  absolutely 
conditioned  by  their  power  to  resist  many  diseases.     Their  houses, 
especially   in   their    great    cities,   were    dark,   ill-ventilated,    and 
crowded  both  with  men  and  microbes.     Their  clothes,  which  their 
climate  necessitated  and  custom  and  religion  ordained  even   in 
warmer  regions,  were  vehicles  almost  ideally  adapted  for  the  con- 
veyance of  disease.     On  the  other  side  of  the  Atlantic  were  peoples 
who  had  undergone  no  evolution  against  any  zymotic  malady  except 
malaria,  and  against  the  latter  only  in  the  wooded  tropical  parts. 


DISEASE  IN  THE  NEW  WORLD  279 

To  them  came  Eastern  civilization,  not  by  slow  degrees,  as  it  had 
dawned  on  the  inhabitants  of  the  Old  World,  but  suddenly,  and, 
in  its  consequences,  fearfully.  The  aborigines  could  not  in  a  few 
generations  achieve  an  evolution  which  the  Europeans  had  accom- 
plished only  during  the  lapse  of  thousands  of  years  and  at  a  cost  of 
millions  of  lives. 

463.  At  once  the  very  ancient  conditions  of  the  Old  World 
were  reproduced.     Air-  and  water-borne  diseases  began  to  sweep  in 
great  waves  of  pestilence  over  the  whole  vast  regions  of  the  West. 
The  entire   population   was   susceptible ;   and,  therefore,    almost 
every  individual  was  stricken  down.     Each  disease  took  its  toll  of 
victims,  and  then,  its  nutritive  supply  exhausted,  passed,  but  only 
to  return   after   intervals  of  years  in    the  same   epidemic  form. 
Towns  and  cities  of  the  European  type,  foci  of  endemic  disease, 
arose  on  the  seaboard,  extended  into  the  interior,  and  provided 
the   starting-point    of    fresh   epidemics.      Measles,   cholera,   and 
especially  smallpox,  penetrated  into  remote  prairies  and  forests, 
and   piled    the    earth    with   the   dead.      Since   the   invasion    by 
Europeans  was  rapid,  and  the  aborigines  had  achieved  no  ante- 
cedent evolution,  the  epidemics  were  more  frequent  than  anciently 
in  the   Eastern   Hemisphere,  and  more   deadly  in   their   effects. 
Whole  tribes  and  nations  were  exterminated.1 

464.  The  part  played  by  tuberculosis,  though  less  striking  and 
obvious,  and  therefore  less  noticed  by  historians,  was  even  greater. 
Prevailing  mainly  in  the  North  and  South,  in  the  neighbourhood 
of  European  settlements  and  missionary  establishments,  it  spread 
with  their  extension  into  the  interior  and  swept  the  land  quite 
bare  of  its  native  inhabitants.     It  completed  the  destruction,  begun 
by  air-  and  water-borne  diseases,  of  the  natives  even  of  the  tropical 
West  Indian  Islands  and  parts  of  the  adjacent  mainland,  especially 
in  the  neighbourhood  of  mines,  in  which  aborigines  were  forced  to 
labour  and  where  the  malady  prevailed  to  a  terrible  extent.     But 
in  the  mainland  of  tropical  America,  where  the  great  forests  were 
defended  by  malaria  which  prevented  white  settlement,  and  by 
heat  which  necessitated  the  building  of  airy  dwellings,  it  did  com- 
paratively little  harm.     Moreover,  the  whites  intermarried  with  the 
aborigines,  and  the  mixed  race  which  resulted,  inheriting  in  half 
measure  powers  of  resisting  both  malaria  and  tuberculosis,  seems, 
as  in  Mexico,  destined  to  survive.     In  North  America  and  in  the 
open  pampas  about  the  river  Plate,  the  work  of  extermination  was 
more  thorough.     Many  unions  occurred  between  the  whites  and 

1  Hirsch,  vol.  i.  p.  136. 


280  EPIDEMIC  AND  ENDEMIC  DISEASE 

the  aborigines.  But  except  on  the  distant  frontiers  the  native 
women  perished  or  were  sterile  through  ill-health,  and  even  the 
half-caste  children  could  not  survive  under  the  conditions  that 
were  created.1  The  natives  melted  away,  and  now  are  found  almost 
solely  in  remote  and  thinly  populated  wilds,  where  a  nomadic  life 
affords  some  protection.  The  white  colonization  of  Australasia 
is  having  similar  results.  In  Polynesia,  as  soon  as  the  trader 
brings  his  clothes  and  the  missionary  insists  on  his  converts  wear- 
ing them  and  attending  crowded  churches  and  schools,  the  work  of 
extermination  begins. 

465.  In  Asia  and  Africa,  where  Europeans  have  made  many 
conquests   and  native   wars  have  been  as  many  and  as  bloody 
as   in   the   West,    every  European   settlement   has   a   flourishing 
native  suburb.     But  throughout  America  and  Australasia  no  con- 
siderable European  town  has  a   native  quarter.     This   one   fact 
brings  into  startling   prominence  the   difference  between  the  in- 
habitants   of    the    East    and   West.      The    latter   were   able    to 
found  settled  communities  and  even  cities  before  the  advent  of 
tuberculosis.     Since  its  arrival  even  nomadic  life  is  hardly  possible 
to  them. 

466.  Writing  of  the  Spanish  occupation  of  the  West  Indies,  the 
historian  Froude  declares,  "  The  Carib  races  whom  the  Spaniards 
found  in  Cuba  and  St  Domingo  had  withered  before  them  as  if 
struck  by  a  blight.    Many  died  under  the  lash  of  the  Spanish  over- 
seers.    Many,  perhaps  the  most,  from  the  mysterious  causes  which 
have  made  the  presence  of  civilization  so  fatal  to  the  Red  Indians, 
the  Australians,  and  Maoris.     It  is  with  man  as  it  is  with  animals. 
The  races  that  consent  to  be  domesticated,  prosper  and  multiply ; 
those  that  cannot  live  without  freedom,  pine  like  caged  eagles,  or 
disappear  like  the  buffaloes  of  the  prairies.     Anyway,  the  natives 
perished  out  of  the  islands  of  the  Caribbean  Sea  with  a  rapidity 

1  The  fact  that  half-castes  abound  in  tropical  America  but  are  comparatively 
rare  in  the  North  has  an  interesting  bearing  on  the  Mendelian  hypothesis.  It 
has  been  surmised  that  the  inheritance  of  susceptibility  and  resisting  power  to 
disease  is  alternative.  But  if  that  were  true,  and  if  the  independent  inheritance 
of  characters  be  also  a  fact,  half-castes  should  abound  in  the  North  as  much  as 
in  the  South,  and  be  as  capable  of  dwelling  in  tubercle-infested  cities  as  Europeans- 
A  proportion,  while  displaying  a  Mendelian  mixture  of  Indian  and  European 
characteristics,  should  inherit  fully  the  powers  of  resisting  consumption  possessed 
by  their  white  ancestors.  Obviously,  since  they  persist  in  the  tropics,  where 
selection  by  tuberculosis  is  less  stringent,  but  perish  in  the  temperate  regions, 
where  it  is  more  severe,  the  '  inheritance  '  of  resisting  power  is  blended,  not 
alternative  ;  wherein  it  accords  with  all  other  human  racial  traits  except  eye 
colour. 


CAUSES  OF  DEATH  281 

which  startled  the  conquerors.  The  famous  Bishop  Las  Casas 
pitied  and  tried  to  save  the  remnant  that  was  left.  The  Spanish 
settlers  required  labourers  for  the  plantations.  On  the  continent 
of  Africa  were  another  race,  savage  in  their  natural  state,  which 
would  domesticate  like  sheep  and  oxen,  and  learnt  and  improved 
in  the  white  man's  company." 

467.  These  sentences  are  typical  of  much  that  has  been  written 
concerning  the  decay  of  the  New  World  races.     Almost  all  writers 
unite  in  speaking  of  it  as  mysterious,  and  yet  the  facts  are  patent 
to  all  observers  on  the  spot.     There  is  no  more  mystery  connected 
with  their  decay  than  with  the  extinction  of  the  dodo  and  the 
bison.     It  cannot  be  doubted  that  the  races  of  the  New  World 
have    suffered    or    are    suffering    extinction    in    consequence    of 
the  introduction  amongst  them  of  Old  World  microbic  diseases, 
and  because  of  one  other  cause,  also  an  importation,  of  which 
more  hereafter.1 

468.  Like   the   imported    African    slaves    that   suffered   from 
sleeping  sickness,  and  perhaps  also  Swiss  mountaineers  who  are 
said  to  die  of  nostalgia,  but  probably   fall   victims   to   microbic 
disease,  they  perish  of  physical,  not  mental   decline.     Their  in- 
capacity to  achieve  European  civilization  is  mainly  corporal,  not 
psychical.    That  much  is  quite  beyond  dispute  and  may  be  verified 
by  reference  to  the  reports  of  all  the  Departments  of  Public  Health 
in  America,  Australasia,  and  Polynesia.     These  show  quite  deci- 
sively that  the  proportionate  mortality  of  the  natives  is  very  high, 
that  they  perish  on  the  average  at  an  exceptionally  early  age,  and 
that  the  causes  of  their  deaths  are  our  imported  diseases.      Their 
families  are  abnormally  small ;    but   we   need    not,  as  so  many 
writers  have  done,  seek  a  mystical  explanation.     Presumably,  in 
the   New   World   as   in    the    Old,  amongst   natives   as   amongst 
Europeans,  ill-health  is  one  of  the  causes  of  sterility. 

469.  Anciently  the  inhabitants  of  conquered  territories  were 
put  to  the  sword,  and  thus  were  never  again  a   menace   to  the 
invaders.     In   this   manner   the   Jews   established   themselves   in 
Palestine,  and,  apparently,  the  Saxons  in  England.     Zengis  Khan 
is  said  to  have  destroyed  eighteen  millions  of  people  in  China 
alone.      Red   Indians   and    Maoris   sought   to   exterminate   their 
enemies,  as  do  African  and  Polynesian  savages  at  the  present  day. 
Civilized  peoples  fight  to  conquer,  not  to  destroy.    Rome  extended 
her  sway  over  many  lands,  the  inhabitants  of  which  prospered  and 
multiplied  under  her  rule.   Similarly,  the  Normans  in  England  and 

1  See  chapters  xv.  and  xvi. 


282  EPIDEMIC  AND  ENDEMIC  DISEASE 

the  English  in  Wales  merely  administered  the  conquered  territory. 
England  and  Russia  govern  empires  vaster  than  the  Roman, 
and,  so  far  from  making  any  conscious  effort  to  root  out 
the  subject  races,  endeavour  to  render  them  peaceful  and 
prosperous. 

470.  But  if  history  teaches  anything  with  plainness,  it  is  the 
lesson  that  conquest,  to  be  permanent,  must  be  accompanied  by 
the  extermination  of  the  natives ;    otherwise,  in  the  fullness  of 
time,  the  conquered  expel  or  absorb  the  conquerors.     The  Greeks 
and  Romans  were  expelled  from  their  acquisitions.     The  Normans 
were  absorbed.     The  Moors  have  left  scarcely  a  trace  in  Spain. 
The  Irish  continually  threaten  the  expulsion   of  the  English,  to 
whom  the  Welsh  are  united  on  equal  terms.     In  parts  of  South 
America  pure  Spaniards  have  nearly  disappeared.     It  is  folly  to 
suppose  the  European  possessions  in  Asia  and  tropical    Africa 
have  any  element  of  permanency.      The  local  endemic  diseases 
fight  for  the  natives,  who  yearly  grow  more  numerous,  intelligent, 
and  insistent  in  their  demands  for  self-government.     Presently  the 
Europeans,  like  the  Romans,  will  be  expelled.     South  Africa  is 
not  effectually  defended  by  diseases  strange  to  Europeans ;  but 
they  have  imported  none  which  the  natives  are  unable  to  resist. 
Therefore    at   the    Cape    and    in    the   north   of   the    Continent, 
Europeans   are   threatened    with    absorption ;    or    if,   as   is    very 
unlikely,  the  two   races  remain    for  ever  distinct,  with  subjuga- 
tion.   History  affords  no  example  of  a  race  maintaining  perpetual 
supremacy  over  a  more  numerous  subject  people. 

471.  But  in   the  Western   Hemisphere  conquest   has   usually 
been    followed   by   extermination.      Disease   has   wrought   more 
widely  and  not  less  fatally  than  the  sword.     The  races  of  nearly 
half  the  world  are  becoming  extinct,  and  are  being  replaced  by 
races  from  the  other  half,  and  in  this  great  cataclysm  our  own 
people  has  played  a  predominant  part.     The  Spaniards  and  the 
Portuguese,   powerful  maritime  nations  in  the  fifteenth  and  six- 
teenth centuries,  had  the  first  start   in  the  race  and  chose  the 
seemingly   richer   tropics.     But,   checked   by   malaria,   European 
emigration  soon  dwindled.    Possibly  there  are  now  fewer  individuals 
of  pure  European  descent  in  tropical  America  than  there  were 
three  hundred  years  ago.     But  the  Britons,  who  colonized  North 
America  and  at  a  later  date  Australasia,  multiplied  enormously, 
and  the  stream  of  new  colonists,  so  far  from  dwindling,  ultimately 
gathered  volume,  til-1  now  by  far  the  larger  part  of  our  race  resides 
abroad.     Owing  solely  to  the  vast  void  created  by  disease,  a  people 


MICROBES  AS  EMPIRE  BUILDERS  283 

who,  four  centuries  ago,  numbered  no  more  than  the  present  inhabi- 
tants of  Greater  London,  has  increased  nearly  fifty-fold.  The 
greatest  world-force  to-day,  it  seems  certain  to  maintain  its 
position,  for  the  sword  as  a  means  of  founding  permanent  empires 
went  out  of  date  with  the  coming  of  civilization,  and  the  regions 
that  disease  can  lay  waste  are  all  occupied,  not  by  mere  conquerors, 
but  by  colonists  rooted  in  the  soil  and  resistant  to  every  disease 
that  is  likely  to  afflict  them.  No  other  race  in  the  world  has  such 
room  for  growth  and  expansion  as  the  Anglo-Saxon. 


CHAPTER   XV 
ALCOHOL 

The  essential  constituents  of  alcoholic  beverages — The  reasons  why  men 
drink — The  types  of  men  that  drink  for  thirst,  taste,  and  the  cerebral  effects — 
The  question  as  to  whether  alcohol  is  beneficial  or  harmless — The  mental  effects 
produced  by  alcohol  —  Normally  no  man  drinks  except  for  the  pleasure  that 
drinking  affords — Inheritance  and  acqiiirement  in  relation  to  alcohol — The  hypo- 
thesis that  men  drink  in  proportion  as  they  do,  or  do  not,  exercise  self-control — 
The  causes  that  determine  the  extent  of  indulgence — The  inheritance  of  sus- 
ceptibility to  the  charm  of  alcohol — Individuals  differ  as  regards  susceptibility — 
Selection  in  relation  to  alcohol. 


w 


472.  ~^~^  T'E  see,  then,  that  disease  is  the  only  factor,  at  any 
rate  the  only  clearly  recognized  factor,  of  selective 
elimination  sufficiently  stringent  amongst  civilized 
men  to  be  a  cause  of  progressive  evolution.  The  racial  changes 
resulting  from  it  have  rendered  many  peoples  of  the  Old  World  so 
resistant  to  the  endemic  diseases  of  their  own  countries  that  they 
are  now  able  to  dwell  in  large  and  settled  communities  and  so 
achieve  civilization.  On  the'other  hand,  civilization,  with  its  dense 
populations  and  constant  intercourse  with  distant  peoples,  has 
conveyed  to  and  rendered  prevalent  in  every  country  the  diseases 
to  which  the  environment  is  suitable.  The  races  to  which  civiliza- 
tion with  its  endemic  diseases  came  so  slowly  that  the  birth-rate 
tended  to  exceed  the  death-rate,  are  adapting  themselves  to  the 
new  conditions.  The  rest  have  become  extinct  or  are  drifting 
towards  extinction. 

473.  But  parasitic  micro-organisms  are  not  the  only  causes  of 
selective  disease  amongst  civilized  men.  Certain  narcotics,  of 
which  the  principal  are  alcohol  and  opium,  are  causes  of  disease, 
disablement,  and  death,  as  stringently  selective  and  as  widespread 
as  any  parasitic  species.  Unfortunately,  we  now  enter  a  region 
of  discussion  which  has  ever  been  a  playground  of  passion  and 
prejudice,  born,  on  the  one  hand,  of  self-interest,  and,  on  the  other, 
of  a  fanaticism  as  unreasoning  as  any  that  has  been  displayed  in 
religious  controversy.  Here  the  disputants  have  belonged  mainly 
to  classes  peculiarly  unfitted  for  the  calm  discussion  of  what  are 

284 


ALCOHOLIC  BEVERAGES  285 

really  abstruse  problems  in  heredity  and  psychology.  No  state- 
ment has  been  too  obviously  absurd  for  acceptance  or  too  obviously 
true  for  rejection  by  the  one  side  or  the  other.  Nevertheless,  in 
dealing  with  alcohol  we  possess  one  great  advantage  :  most  people 
are  able  to  appeal  not  only  to  the  observations  of  others,  but  to 
their  own  sensations.  If  the  reader  has  anything  like  an  average 
knowledge  of  life,  he  will  possess  ample  materials  drawn  from  his 
personal  experience  on  which  to  found  a  judgment.  In  science 
independent  thought,  founded  if  possible  on  first-hand  knowledge, 
is  not  only  a  right  but  a  duty.  Applying  the  broad  principles  of 
heredity  already  laid  down,  I  shall  set  forth  conclusions  which 
conflict  with  popular  beliefs,  but  which,  I  think,  the  reader  will  find 
not  altogether  unreasonable. 

474.  The  essential  constituents  of  every  alcoholic  beverage  in 
common   use   are   alcohol,  certain   flavouring  agents,  and  water. 
These  three  constituents  attract  three  separate  classes  of  drinkers ; 
or,  at  any  rate,  they  supply  separate  and  unlike  motives  for  drink- 
ing, one  or  other  of  which  predominates  in  every  drinker.     Water 
is  an  essential  part  of  our  bodies.     When  the  quantity  within  us 
becomes  deficient,  we  crave  to  renew  it,  and  this  instinctive  crav- 
ing we  term  thirst.     Many  men  drink  alcohol  only  when  they  are 
thirsty.     The  thing  primarily  desired  by  them  is  water.     Alcohol 
is  added,  as  lime-juice  might  be,  merely  as  a  flavouring  agent,  as 
something  which  renders  the  necessary  draught  of  water  more  pleas- 
ing.     Drinkers  of  this  sort  usually  prefer  the  lighter  beverages, 

'such  as  beer  and  wines,  which  contain  a  considerable  proportion  of 
water.  Other  men  drink  alcohol  mainly  to  gratify  the  sense  of 
taste — to  produce  pleasant  sensations  by  stimulating  certain  nerve- 
endings  in  the  mouth.  The  average  connoisseur  is  a  typical 
example.  He  drinks  for  precisely  the  same  reason  as  a  child 
consumes  sweets,  and  he  always  chooses  the  beverages  most 
palatable  to  him.  The  third  class  of  drinkers  comprises  people 
who  desire  to  experience  the  various  sensations  which  result  from 
alcohol  circulating  in  the  blood  and  acting  directly  on  the  central 
nervous  system,  the  brain — sensations  of  well-being,  of  exhilaration, 
of  confidence,  of  general  happiness,  of  comfort,  of  cheerfulness,  of 
restfulness,  of  somnolence,  and  so  forth,  which  in  different  drinkers 
mark  different  stages  of  intoxication.  A  drinker  of  this  sort, 
especially  if  his  desires  are  very  strong  and  he  is  unable  to  procure 
anything  more  palatable,  may  drink  thirst-creating  and  nauseous 
compounds  such  as  methylated  spirits. 

475.  Of  course   the   three   primary   constituents   of   alcoholic 


286  ALCOHOL 

beverages,  the  three  sets  of  sensations  to  which  they  give  rise,  may 
all  attract  a  given  drinker  at  one  and  the  same  time ;  or  a  man 
may  drink  at  first  to  satisfy  his  thirst  or  his  palate,  and  later  for 
the  sake  of  the  feelings  which  accompany  intoxication  ;  or  in  the 
beginning  of  his  career  as  a  drinker  he  may  be  influenced  mainly 
by  one  or  other  of  the  former  motives,  but  later  in  life  mainly  by 
the  last.  Nevertheless,  the  fact  remains  that  the  three  main  con- 
stituents are  distinct,  the  desires  they  gratify  are  utterly  distinct, 
and  that,  while  some  drinkers  are  influenced  solely  by  one  of  these 
desires,  all  drinkers  are  influenced  at  any  given  moment  more  by 
one  of  them  than  by  the  others.  The  heated  cyclist  or  cricketer, 
who  gulps  a  quart  of  light  beer  and  is  satisfied,  evidently  seeks 
sensations  which  are  not  the  same  as  those  desired  by  the  con- 
noisseur toying  with  his  choice  wine,  smelling,  sipping,  rolling  it  in 
his  mouth  so  as  to  get  all  the  enjoyment  possible  from  its  taste 
and  aroma ;  nor  the  same  as  those  sought  by  the  man  who  desires 
a  'stimulant'  or  'night-cap,'  or  who  with  deeper  longing  craves 
intoxication,  and  drinks  perhaps  with  a  shudder  some  strong  and 
it  may  be  distasteful  spirit  which  increases  his  thirst. 

476.  Thirst  and  taste  are  not,  by  themselves,  causes  of  excessive 
indulgence.     Both   are   satisfied   by   a   very  moderate  degree   of 
indulgence ;  and  the  experienced  drinker,  who  knows  what  sensa- 
tions to  expect  from  various  amounts  of  the  beverage  he  is  imbibing, 
soon  learns  the  quantity  which  will  afford  him  the  greatest  gratifica- 
tion.    Both  thirst  and  taste  are  incentives  to  instinctive  actions. 
The  former  impels  to  the  drinking  of  dilute  beverages,  and  ceases  as* 
soon  as  sufficient  water  is  imbibed ;  while  the  palate  is  cloyed  by 
a  few  glasses  even  of  the  choicest  wine,  just  as  it  would  be  by  the 
best  of  sweets.     Excessive  drinkers  are  drawn  solely  from  the  class 
that  seeks  the  sensations  produced  by  alcohol  when  acting  directly 
on  the  brain.     Of  course,  however,  not  every  drinker  who  belongs 
to  this  latter  class  takes  alcohol  in  excess.     Many,  if  not  most,  in 
England  at  least,  take  no  more  than  they  would  if  impelled  by 
thirst  or  taste. 

477.  It  is  a  moot  point  whether  alcohol  in  small  quantities — 
the  quantities  that  are  drunk  by  the  '  moderate '  people  we  meet  in 
society,  who  are  able  to  go  about  the  occupations  of  life  apparently 
unaffected    mentally — is    injurious.      Many   people,   including    a 
minority   of  medical    men,   declare   that   the    smallest    amounts 
are   harmful,  and  support  their  contention  by   an    appeal  to  the 
statistics  of  insurance  companies,  some  of  which  place  in  different 
classes  total  abstainers  and  moderate  drinkers,  and  report  that  the 


ALCOHOL  AND  DISEASE  287 

former  live,  on  the  average,  distinctly  the  longer.  But  all  inebriates 
are  not  paragons  of  candour.  None  who  seek  to  insure  their  lives 
will  admit  that  they  are  other  than  moderate.  Were  they  so 
honest  as  to  admit  excessive  drinking  they  would  not  court 
inevitable  rejection  by  presenting  themselves  for  medical  examina- 
tion.1 There  can  be  no  doubt  that  many  people  who  have  insured 
as  moderate  drinkers  really  indulge  to  excess.  Probably  most 
medical  examiners  have  experienced  the  humiliation  of  having 
recommended  to  insurance  companies  individuals  who  declared  they 
were  temperate  and  showed  no  signs  that  they  were  otherwise,  but 
who  were  subsequently  discovered  to  be  much  the  reverse.  If  we 
accept  the  dictum  that  the  smallest  quantity  of  alcohol  is  injurious, 
we  must  believe,  contrary  to  the  evidence  of  our  senses,  that  whole 
nations  like  the  Italians  suffer  chronic  ill-health.  Some  men  are 
much  more  resistant  to  alcohol,  physically  and  mentally,  than  others. 
I  have  known  many  excessive  drinkers  who  have  survived  till  old 
age.  Others  perish  early  in  life.  Doubtless  the  truth  is  that, 
while  large  quantities  of  alcohol  are  injurious  to  all  men,  they 
are  less  injurious  to  some  men  than  to  others ;  and  that,  while 
small  quantities,  such  as  are  drunk  by  Italian  peasants,  are  in- 
jurious to  some  men,  they  are  little,  if  at  all,  injurious  to  most  men. 

478.  Probably  no  substance  that  is  eaten  or  drunk  produces 
quite  the  same  sensations  in  every  one.     One  man  prefers  beef, 
another  mutton,  a  third  pork  ;  one  prefers  apples,  another  oranges  ; 
one  tea,  another  coffee  ;  one  delights  in  tobacco,  another  derives  no 
pleasure    from    it.     If  their  sensations    were   exactly  alike,    their 
preferences  would  be  the  same.     Identical  quantities   of  alcohol 
make  some   men  cheerful,  others  maudlin,  others  morose,  others 
amiable,  yet  others  pugnacious ;  some  are  stimulated  to   greater 
activity,  others  are  lulled  to  sleep.     However,  it  is  evident  that 
whatever  his  sensations,  the  habitual  and  excessive  drinker  finds 
them  pleasant,  or  he  would  not,  in  spite  of  heavy  penalties,  seek  to 
renew  them  periodically. 

479.  In  one  particular  all  excessive  drinkers  agree  :  they  pay 
for  the  pleasant  sensations  experienced  when  alcohol  is  circulating 
in  the  blood  by  feelings,  following  its  elimination  from  the  body, 
which  are  the  reverse  of  pleasant — sensations  of  abnormal  thirst, 
headache,    nausea,    nervousness,   wakefulness,    irritability,   terror, 

1  One  Canadian  company  which  does  business  in  this  country  demands  from 
its  '  proposers  '  a  declaration  of  the  number  of  times  they  have  been  drunk 
during  the  past  five  years,  and  the  date  of  the  last  occasion.  If  nothing  else  is 
elicited,  at  least  a  maximum  of  lying  is. 


288  ALCOHOL 

delirium,  and  the  like,  which  indicate  temporary  or  permanent 
impairment  of  health.  In  some  cases,  especially  with  habitual 
drinkers,  these  disagreeable  sensations  are  temporarily  alleviated 
by  further  indulgence  in  alcohol,  the  drinker  taking  "  a  hair  of 
the  dog  that  bit  him."  Doubtless  the  fact  that  drinking  often 
affords  temporary  relief  from  the  after  effects  of  previous  indulgence 
conduces  to  continued  indulgence.  Some  writers  seem  to  hold 
a  belief  that  it  is  the  sole  cause  of  all  excessive  drinking,  at  any 
rate  of  all  excessive  drinking  that  is  of  importance.  Obviously, 
however,  they  are  mistaken.  A  week's  incarceration  in  prison,  which 
may  remove  every  unpleasant  sensation,  will  seldom  cure  a 
habitual  drinker.  Sailors,  who  start  on  a  long  voyage  in  miserable 
case  but  return  perfectly  cured,  are  as  prone  as  any  class  to  deep 
indulgence.  Years  ago  I  lived  in  New  Zealand  with  bushmen  and 
"  gum  diggers."  Alcohol  was  not  obtainable  in  the  neighbourhood. 
Some  of  my  companions,  men  in  splendid  health  and  vigour, 
dreamed,  as  of  heavenly  delights,  of  the  week  or  fortnight  of 
furious  drinking  in  which  they  were  wont  to  dissipate  the  earnings 
of  months.  Clearly,  then,  the  craving  for  drink  is  not  always  due 
to  a  longing  to  counteract  the  ill-effects  of  previous  indulgence,  but 
to  a  recollection  of  its  delights.  The  relief  which  continued 
drinking  affords  is  a  contributory  cause,  but  never,  of  course,  the 
primary  cause.1 

480.  The  craving  for  alcohol  is  a  resultant  of  two  factors.  The 
first  is  an  inborn  (nutritional)  capacity  to  enjoy  or  develop  a  power 
of  enjoying  the  sensations  that  alcohol  awakens.  The  second  is  a 
recollection  of  the  sensations  aroused  by  previous  acts  of  drinking. 
No  one  could  possibly  crave  for  indulgence  in  alcohol  unless  he 
were  so  constituted  as  to  enjoy  the  effect — any  more  than  he  could 
crave  for  a  draught  of  sea-water.  On  the  other  hand,  no  one  is  born 
with  a  knowledge  of  the  sensations  aroused  by  drinking,  therefore 
none  can  crave  for  them  without  a  recollection  of  previous  experi- 
ence. It  is  true  that  a  man  who  has  heard  of  the  delights  of 
drinking  may  desire  alcohol  in  the  sense  that  a  boy  desires  tobacco, 
or  an  Englishman  some  tropical  fruit ;  but  this  desire  is  quite 
distinct  from  that  which  besets  the  experienced  toper.  Both  these 
desires,  again,  are  distinct  in  type  from  hunger,  or  thirst,  or  the 

1  This  discussion,  with  much  else  in  the  present  chapter,  may  appear  childish 
to  the  reader — an  attempt  to  prove  the  obvious.  But  it  must  be  borne  in  mind 
that  we  are  now  dealing  with  a  subject  about  which  an  incredible  amount  of 
nonsense  has  been  written  and  accepted.  It  is  necessary,  therefore,  to  demon- 
strate even  the  very  obvious. 


SUSCEPTIBILITY  TO  ALCOHOL  289 

sexual  craving.  The  latter  are  instincts, '  inborn  '  characters,  which 
develop  inevitably  as  the  body  develops,  and  which,  though  they 
may  be  awakened  to  activity  by  fitting  stimulus  (the  presence  of 
food,  water,  or  a  particular  mate),  are  not  then  created  by  it  in  the 
sense  meant.  In  other  words,  they  are  not,  like  the  drinker's  longing 
or  the  boy's  desire  for  tobacco,  necessarily  dependent  on  memory. 

481.  Mental  differences  in  relation  to  other  narcotics  are  just  as 
marked  as  in  relation  to  alcohol.     For  example,  some  natives  of 
China  are  satisfied  with  a  very  moderate  indulgence  in  opium ;  in 
others  the  craving  is  so  strong  that,  in  effect,  they  commit  suicide 
to  gratify  it.     The  insensibility  which  follows  the  inhalation   of 
chloroform    is  a  form  of  intoxication.     Most   people   who   have 
experienced  it  only  once  or  twice  describe  the  sensations  of '  going 
off'   and    'coming   to'  as  horrible.     But   often    pleasure   attends 
wider   experience.     Some    people   find   pleasure   even    from    the 
beginning.     Once  a  woman,  who  was  inhaling  the  drug  for  the 
first  time,  said  to  me,  "  You  are  sending  me  into  heaven."     I  knew 
a  doctor's  servant  who  was  in  the  habit  of  stealing  her  master's 
chloroform  and  rendering  herself  deeply  insensible. 

482.  The  individuals  of  every  species  vary  from  one  another  in 
every  particular.     Probably  there  is  not  on  earth  an  individual 
who  is  exactly  like  another  in  any  character.     We  have  seen  that 
men  manifestly  vary  in  the  sensations  aroused  in  them  by  alcohol 
— in  the  amount  of  pleasure  which  drinking  confers,  and  conse- 
quently in  the  degree  in  which  they  are  tempted  to  repeat  the 
remembered  experience.     Some  men  who  have  taken  alcohol  all 
their  lives  experience,  apparently,  not  much  more  pleasure  from 
the   act   than  they  derive  from  the  eating  of  an   apple.     Their 
temptation  to  deep  indulgence  is  of  the  slightest.     From  first  to 
last  they  are  attracted  more  by  thirst  or  taste  than  by  the  cerebral 
effects.     But  beyond  question  the  longing  awakened  in  other  men 
is  very  intense.     A  woman  inebriate,  in  desperate  straits  for  drink, 
once  procured  alcohol  by  a  trick — the  amputation  of  her  own  hand. 
Pathological  specimens  in  hospital  museums,  gruesome  prepara- 
tions of  cancers,  diseased  intestines,  and  the  like,  have  been  spoilt 
because  people  who  had  access   to  them  drained  the  methylated 
spirits  in  which  they  were  preserved. 

483.  Until  very  recently   the  vitally  important  fact  that  the 
degrees  in  which  men  are  tempted  by  alcohol  differ  greatly  was 
hardly  recognized.1     Even  now  very  many  well-meaning  people, 

1  As  far  as  I  am  aware  it  was  not  recognized  before  1896,  when  I  published 
The  Present  Evolution  of  Man. 

19 


290  ALCOHOL 

who  think  it  is  in  conflict  with  their  schemes  of  temperance  reform, 
endeavour  to  push  it  as  much  as  possible  into  the  background. 
At  any  rate  it  was  and  is  quite  ignored  in  all  discussions  on  intem- 
perance. Men  are  supposed  to  be  temperate  or  the  reverse  solely  in 
proportion  as  they  exercise,  or  do  not  exercise  self-control  ;  or, 
what  is  very  much  the  same  thing,  in  proportion  as  they  have  or 
have  not  been  well  trained.1  But  since  there  are  men  who,  very 
plainly,  are  intensely  tempted  by  alcohol,  this  hypothesis  carries 
the  corollary  that  all  men  who  drink  at  all  crave  furiously  for  the 
sensations  awakened  by  deep  indulgence,  and  differ  among  them- 
selves only  because  some  of  them  exercise  strenuous  restraint. 
But  let  the  reader  turn  to  the  best  of  all  guides  for  him,  his  own 
experience  of  life.  He  is  sure  to  have  known  many  inebriates, 
men  whose  desires  for  alcohol  were  as  those  of  a  shipwrecked 
sailor  for  water.  Some  of  them  he  has  seen  to  struggle  desperately 
if  unavailingly  against  an  overwhelming  desire.  As  much  as  any 
man  they  seek  to  exercise  self-restraint.  Next  let  him  examine 

1  "  It  is  often  alleged,  it  is  still  more  often  assumed  that  the  difference  between 
the  sober  man  and  the  drunkard  is  that  the  one  possesses  and  the  other  lacks 
sufficient  self-control  to  enable  him  to  overcome  his  urgent  and  masterful  desire 
for  drink.     The  repetition  from  mouth  to  mouth,  and  from  book  to  book,  of  this 
obviously  false  doctrine  is  one  of  the  most  striking  instances  of  the  ovine  imitative- 
ness  of  the  human  intellect,  and  of  the  ingrained  habit  of  yielding  unquestioning 
assent  to  authority.     There  are  countless  millions  of  sober  men  and  women  in 
the  world,  all  of  whom  are  ready  to  utter  the  parrot  cry  that  they  are  sober 
because  of  their  superior  self-control,  because  they  have  the  strength  to  resist 
temptation  ;  and  this  they  say  in  perfect  good  faith,  when,  if  they  would  only 
think    for  one  moment  and  interrogate  their  own  consciousness   in  their  own 
experience,  they  could  not  fail  to  know/with  irresistible  conviction,  that  in  fact  they 
are  not  tempted  to  drink  at  all.     Drink  has  no  temptation  for  them.     It  offers 
them  no  allurement.     It  yields  them  no  delight.     It  satisfies  no  craving.     The 
taste  of  it  finds  them  as  indifferent  as  it  leaves  them.     They  are  drink-proof,  not 
because  of  any  superior  virtue,  not  because  of  any  superiority  of  self-control, 
but  because  drink  holds  out  to  them  no  temptation      And,  not  being  tempted, 
they  do  not  fall.     They  are  no  more  meritorious  for  not  getting  drunk  than  a  cat 
is  meritorious  for  not  wetting  its  feet,  or  a  child  is  meritorious  for  not  falling 
to  the  ground.     Many  such  persons  could  not  get  drunk  if  they  tried.     The 
sensations  produced  by  the  ingestion  of  alcohol  are  to  them  so  unpleasant  that 
they  are  compelled  to  leave  off  long  before  they  have  taken  enough  to  make  them 
drunk.     If,  then,  the  difference  between  the  drunkard  and  the  sober  person  is  not 
a  difference  in  self-control,  what  is  it  ?  .  .  .  The  facts  are  that,  on  the  one  hand, 
when  alcohol  is  applied  in  solution  in  the  blood  to  the  brain  tissue  of  one  person, 
there  arises  in  that  person  pleasurable  feeling.     When  applied  in  solution  in  the 
blood  to  the  brain  tissue  of  another  person,  there  occurs  in  that  person  no  such 
pleasurable  feeling.     The  feeling  is  neutral,  or  is  unpleasurable,  or  is  displeasur- 
able."    (Mercier,  The  Presidential  Address  on  the  Physical  Basis  of  Mind,  delivered 
at  the  sixty-seventh  annual  meeting   of  the  Medico-Psychological  Association, 
July  23rd  and  24th,  1908.) 


THE  TEMPERAMENT  OF  THE  DRUNKARD    291 

his  own  emotions.  Is  he  so  miserable  as  to  be  afflicted  by  this 
intense  and  tormenting  desire  ?  Is  he  saved  from  that  which  will 
wreck  home  and  happiness  and  life  only  by  an  effort  as  tremendous 
as  and  more  sustained  than  that  which  keeps  the  sailorjfrom  draining 
his  last  drops  of  water  ?  Or  is  it  a  fact  that  his  desires  for  deep 
indulgence  are  very  faint — as  faint  as  the  everyday  desire  of  a 
landsman  for  water,  so  faint  or  non-existent  that  he  is  hardly,  if 
at  all,  conscious  of  them  ?  What  of  the  people  he  knows  best,  his 
own  relatives  and  intimate  friends  ?  Are  the  majority  of  them 
deeply  tempted  ?  Has  he  any  valid  reason  for  supposing  that  the 
lady  whom  he  meets  at  dinner,  and  who  sips  her  glass  of  wine  in 
such  seeming  contentment,  is  earnestly  desirous  of  draining  the 
decanter  ?  It  is  sufficient  merely  to  ask  the  question  to  demon- 
strate its  absurdity. 

484.  For  the  sake  of  comparison,  it  may  be  worth*  while  to 
describe  my  own  feelings  at  the  present  moment.     If  a  glass  of 
beer  were  before  me,  I  should  feel  no  inclination  for  it,  though  I 
am  capable  of  enjoying  beer  when  thirsty.     If  a  glass  of  some 
sweet  wine  were  here,  I  should  enjoy  perhaps  half  a  glass,  just  as  I 
should  enjoy  a  morsel  of  chocolate.     When  I  was  younger  and  my 
delight  in  sweets  greater,  I  should  have  liked  more.     A  glass  of 
whisky  would  awaken  only  repulsion.     When  sleepless  or  tired  or 
when  with  friends  I  have  often  found  it  pleasant.     I  find,  however, 
that  even  a  small  amount  affects  me  disagreeably  some  hours  later, 
and  therefore  as  a  rule  I  take  none.     I  am  not  conscious  at  any 
time  of  having  exercised  any  self-control  worth  mentioning.     I 
dare  say  many  people  will  doubt  the  truth  of  this  introspection 
— especially  abstainers  who  have  had   no  experience,  and  people 
to   whom    even   a   glass   of  methylated   spirits   is  a  temptation. 
But  I  think  a  great  many  others  will  find  a  parallel  in  their  own 
experience. 

485.  Plainly,  then,  as  in  the  case  of  tobacco,  a  lifelong  experi- 
ence  of  alcohol    endows  some  men  with  only  weak  and  easily 
satisfied  desires,  whereas  a  much  shorter  experience  awakens  in 
others  a  keen  longing  which  is  satisfied  with  nothing  short  of  deep 
indulgence,    or   is    resisted    only  at   the   cost  of   acute  suffering. 
Plainly  again,  not  only  does  alcohol  awaken  deeper  desires  in  some 
men   than   in  others,  but  it  awakens  them   more  quickly.     Self- 
control,  therefore,  though  a  factor  of  great  importance,  is  not  the 
only  or  even  the  main  factor  in  the  causation  of  sobriety.     It  is 
argued  sometimes  that  men  are  temperate  or  the  reverse  because 
those  of  the  former  class  have,  from  the  beginning  and  always, 


292  ALCOHOL 

exercised  self-restraint,  and  so  have  never  acquired  through  ex- 
perience the  desires  which  increased  indulgence  creates  in  the  latter. 
But  we  all  know  men  and  women  whose  whole  lives  are  abandoned 
to  an  unrestrained  search  for  pleasure,  and  who  are  nevertheless 
temperate  in  their  drinking.  Is  it  believable  that  these  people  con- 
stantly resist  urgent  temptation  which  they  continually  feed  with 
inadequate  indulgence?  Abstainers  form  a  class  by  themselves. 
They  are  not  exposed  in  the  same  way  to  temptation.  But  pro- 
bably the  reader  is  a  moderate  drinker.  Let  him  inquire  of  his 
own  sensations. 

486.  Just   as   a   limited    experience    enables   the   smoker    to 
ascertain  the  amount  of  tobacco  and  the  periods  and  methods  of 
indulgence  which  are  most  agreeable  to  one  of  his  type,  so  a 
certain  experience  endows  the  drinker  with  a  similar  knowledge. 
As  we  see,  some  men,  influenced  mainly  by  thirst  or  taste,  are 
satisfied  with  a  glass  at  meals.     Others  are  satisfied  with  nothing 
short  of  complete  insensibility.     Some,  desiring  only  the  drowsiness 
which  alcohol  creates  in  them,  take  a  "  night-cap  "  ;  others  must  be 
sipping  the  whole  day.     In  the  latter  case  the  drinker  may  not, 
and  usually  does  not  become  intoxicated  in  the  ordinary  accept- 
ance  of  the   word  ;    but   a   mental   condition  which  borders   on 
intoxication  is  so  pleasant  to  him  that  he  seeks  to  maintain  it 
constantly  during  his  waking  hours,  and  in  this  way  may  imbibe  a 
quantity  of  alcohol  which  may  exceed  the  average  amount  taken 
by  one  who  drinks  when  opportunity  offers  to  the  point  of  coma. 

487.  We  must,  however,  always  bear  in  mind  that  the  drinking 
habits  of  men  are  not  solely  determined  by  the  pleasure  conferred 
by  alcohol.     Many  men  are  unable  to  afford  or  are  otherwise  pre- 
vented   from   obtaining   as   much    as   they  desire.     Some  are  so 
trained  that  they  regard  all  drinking  with  moral  abhorrence,  and 
from  birth  to  death  never  indulge  in  it.     Others,  seeing  the  misery 
of  their  loved  ones,  or  having  the  fear  of  physical,  material,  or 
social  ruin  in  sight,  become  abstainers  later  in  life.     All  normally 
constituted  men  are  greatly  influenced  by  fashion,  that  is,  by  the 
tone  of  the  society  in  which  they  live.     It  is  probable  that  our 
great-grandfathers  encouraged  one  another  to  drink  more,  on  the 
average,   than  they  really  craved.     It  is  certain  that  under  the 
present  fashion  many  men  voluntarily  drink  less  than  they  would 
enjoy.     But  when  all  this  is  granted,  it  still  remains  true  that  a 

given  experience  of  drink  awakens  stronger  desires  in  some  men 
than  in  others,  that  under  any  given  conditions  men  on  the  average 
drink  in  proportion  to  their  desires,  that  the  men  most  tempted 


VARIETIES  OF  DRUNKARDS  293 

most  often  fall,  and  that  the  excessive  drinker,  whether  actual 
inebriate  or  continuous  soaker,  is  invariably  one  to  whom  deep 
indulgence  is  a  strong  temptation  ;  whereas  the  moderate  drinker 
is  almost  as  invariably  one  who  is  so  constituted  that  his  tempta- 
tion is  much  weaker.  All  deep  drinkers  suffer  from  the  immediate  or 
remote  effects  of  poisoning,  and  know  well  to  what  their  sufferings 
are  due.  It  is  almost  inconceivable  that  any  man  would  incur  the 
inevitable  penalties  were  he  not  greatly  tempted.  We  never  hear 
of  men  deliberately  making  themselves  poor,  contemptible,  miser- 
able, and  ill  with  something,  for  example  sea-water,  which  has  no 
intoxicating  effect.  On  the  other  hand,  a  moderate  drinker  who 
has  had  an  average  experience  of  alcohol  and  has  in  him  the 
makings  of  a  drunkard,  is  not  common.  The  human  will  is 
seldom  strong  enough  to  resist  the  steady  pull  of  vehement 
temptation  when  the  latter  is  constantly  fed  by  partial  indulgence. 

488.  Some  drinkers,  it  is  true,  are  so  constituted  that  alcohol 
affords  them  pleasure  mainly  as  a  relief  from  unhappiness.     They 
are  one  variety,  but  on   the  whole   a  somewhat   rare  variety  of 
excessive   drinker.      If  the   reader   will    again    consult    his   own 
experience  of  life,  I  think  he  will  find  that  nearly  all  the  inebriates 
with  whom  he  is  well  acquainted,  slipped,  after  a  longer  or  shorter 
experience,  according  to  the  ease  with  which  strong  desires  were 
awakened  in  them,  into  bad  habits  under  quite  ordinary  conditions 
of  life.     Again,  bad  companionship  is  said  to  lead  to  intemperance, 
and  doubtless  it  often  does.     But  usually  the  zest  for  such  society 
owes  its  origin  to  alcohol,  which  can  furnish  it  only  to  those  who 
are  susceptible  to  its  charm.     "  Birds  of  a  feather  flock  together." 
A  man  who  craves  for  drink  would  hardly  choose  the  society  of 
abstainers  or  moderate  men.     The  kind  of  pleasures  that  appeal  to 
a  more  or  less  inebriated   man    are  not  those  which   appeal  to 
respectable    women,    clergymen,    scientific   men,    or    athletes,    as 
such. 

489.  Now,  since  susceptibility  to  the  charm  of  alcohol  is  an 
*  innate '   character  which   develops  with    the   growth  of  the  in- 
dividual  under    stimulus   of  nutrition,   it   tends    as   such   to    be 
'  inherited,'  in  the  same  sense  as,  for  example,  the  shape  of  his 
head.     In  this  connection  it  matters  not  whether  the  individual 
does  or  does  not  drink.     Awake  or  dormant,  his  susceptibility  is 
still  present.     On  that  account  drunkenness  tends  to  run  in  families. 
The  child  is  "  by  nature  "  similar  to  the  parent,  and  under  similar 
conditions  tends  to  acquire  the  same  trait.      Often,  however,  it 
happens  that  a  sober  or  a  drunken  parent  is  succeeded  by  a  child 


294  ALCOHOL 

who  is  the  reverse.  The  child  has  two  parents,  and  may  inherit 
mainly  or  exclusively  from  the  one  or  the  other.  Or  the  conditions 
of  life  under  which  parent  and  child  develop  may  be  different. 
Thus  a  man,  impressed  by  the  " awful  example"  of  his  father,  may 
become  an  abstainer.  But  his  son,  falling  amongst  evil  companions, 
and  seeing  at  first  more  of  the  delights  than  the  woes  of  drinking, 
may  exhibit  the  character  of  the  grandparent.  The  facts  remain, 
however,  that,  though  many  people  who  are  very  susceptible  to  the 
charm  of  alcohol  do  not  fall  victims  to  it,  yet,  whether  it  be  in- 
dulged or  not,  the  susceptibility  exists,  is  greater  in  some  people 
than  in  others,  tends  to  be  inherited  in  its  various  degrees,  and 
people  on  the  average  tend  to  fall  victims  to  it  in  proportion 
to  its  strength  in  them.  The  clearest  proof  that  degrees  ot 
susceptibility  to  the  charm  of  alcohol  tend  to  be  reproduced  by 
offspring  is  found  when  we  examine  races.  In  the  midst  of 
abundance  of  alcohol,  generations  of  Spaniards  or  Italians  lead 
temperate  lives.  Under  similar  conditions  Englishmen  are  more 
drunken,  Russians  yet  more  drunken,  while  Red  Indians  furiously 
drink  themselves  to  death.  Races  are  merely  aggregates  of  more 
or  less  nearly  related  individuals.  Therefore,  as  in  the  case  of 
disease,  the  individuals  of  each  race  must  tend  to  transmit  their 
degrees  of  susceptibility  to  offspring  and  descendants. 

490.  There  can  be  no  doubt,  then,  that  some  people  are  so 
constituted  as  to  be  more  tempted  by  drink  than  others,  that  they 
tend  to  transmit  this  characteristic  to  offspring,  and  that,  though  a 
proportion  of  those  who  have  it  are,  in  England  at  least,  abstainers,  or 
in  far  rarer  cases  moderate  drinkers,  yet  all  really  excessive  drinkers 
are  drawn  from  their  ranks.  Again,  there  can  be  no  doubt  that 
excessive  drinking  is  injurious,  and  that  a  great  number  of  people, 
all  of  a  particular  type,  indulge  in  it.  The  question  arises,  then, 
whether  it  is  so  injurious  and  to  so  large  a  number  of  people,  as 
to  act,  like  a  microbic  disease,  as  a  stringent  agent  of  selection. 
In  that  case  it  must  so  shorten  or  in  other  ways  so  influence  the 
lives  of  a  certain  type  of  people,  that  the  total  number  of  offspring 
and  descendants  they  contribute  to  the  race  is  much  less  than 
would  have  otherwise  been  reared.  According  to  the  Registrar- 
General,  22 1 1  people  died  of  alcoholism  in  1905,  the  rate  per 
million  of  the  population  being  only  65.  In  the  same  year  the 
deaths  from  tuberculosis  were  55,759,  the  rate  per  million  being 
1632.  Judged,  then,  by  the  returns,  excessive  drinking  is  by  no 
means  a  stringent  agent  of  elimination.  The  number  of  deaths 
recorded  must  bear  a  very  small  proportion  to  the  total  number  of 


THE  ELIMINATION  BY  ALCOHOL  295 

excessive  drinkers.     Must  we  conclude,  then,  that  alcoholism  only 
very  rarely  destroys  its  victims  ? 

491.  The  statistics    of  the    Registrar  -  General    are   compiled 
almost  exclusively  from  medical  certificates  of  death.      When  I 
turn  over  the  counterfoils  of  my  old  books  of  death  certificates,  I 
find,  here  and  there  but  very  seldom,  the  word  '  alcoholism.'     The 
term  implies  that  the  person  whose  end  is  recorded  drank  himself 
quickly,  violently,  and  relentlessly  to  death.      He  or  she  died, 
not  from  the  remote  effects  of  alcohol,  but  from  poison  actually 
circulating  in  the  blood  at  the  time  of  death,  or  during  the  few  days 
or  weeks  preceding.     De  mortuis  nil  nisi  bonum  \  but  I  could  not 
truthfully  enter  anything  else.     Sometimes  such  a  one,  after  a  more 
or   less  prolonged  career  of  drink  and  poverty,  owed  his  actual 
decease  to  a  windfall  of  money.     More  common  is  *  cirrhosis  of  the 
liver,'  an  expression  which  is  usually,  but,  as  Dr  H.  B.  Donkin  has 
shown,  not  always  a  synonym  for  chronic  or  soaker's  alcoholism. 
The  Registrar-General's  returns  indicate  that  4008  persons  died  of 
this  complaint  in    1905,  a  number  which  works  out  at  a  rate  of 
117  per  million  living.     This  number,  even  when  added  to  that 
due  to  acute  alcoholism,  is  too  small  to  indicate  stringent  selection. 

492.  But,  looking  through  my  counterfoils,  I  see  recorded  the 
names  of  many  people  some  of  whom  as  I  knew,  and  more  of  whom 
as  I  suspected,  had  been  injured  by  excessive  drinking  before  they 
died  of  accident   or   contracted   phthisis,  pneumonia,  bronchitis, 
apoplexy,   or   the   more   gradual   forms   of  paralysis,    erysipelas, 
syphilis,  kidney,  heart,  or  arterial  disease,  or  this  or  that  other 
complaint  which  was  the  immediate  cause  of  death.     The  circum- 
stances surrounding  their  ends  make  me  very  sure  that  in  a  large 
proportion   of  cases   they   would  not  have   contracted  the  fatal 
disease,  or  would  have  recovered  from  it  had  they  not  previously 
weakened  their  powers  of  resistance  by  intemperance.    Some  years 
ago  "  The  Harveian  Society  of  London  instituted  an  investigation 
and  found  that  in  London,  of  10,000  persons  dying  over  twenty- 
four  years  of  age,  the  result  was  as  follows : — 

A.  Deaths  in  nowise  due  to  alcohol 8598 

B.  Deaths  accelerated  or  partly  caused  by  its  abuse      .     1005 

C.  Deaths  wholly  due  to  it 397 

.  .  .  These  1402  deaths  constituted  almost  exactly  14  per  cent, 
of  the  total  deaths.  If  this  proportion  still  continues  .  .  .  the 
total  deaths  in  the  United  Kingdom  for  1889,  altogether  or  partly 
caused  by  alcohol  were  94,416,  of  which  26,736  would  be  directly 
due  to  alcohol  and  67,680  accelerated  or  partly  caused  by  it. 


296  ALCOHOL 

...  In  that  inquiry,1  conducted  over  totally  different  grounds, 
the  deaths  of  intemperate  males  of  over  twenty-five  were  30  per 
cent,  of  the  whole,  while  25  per  cent,  were  careless  drinkers,  some- 
times taking  excess.  This  being  the  proportion  among  adult 
males,  we  find  no  difficulty  in  believing  that  about  one  death  in 
seven  is  partly  or  wholly  caused  by  alcohol,  omitting  for  the 
moment  those  caused  indirectly."  2 

493.  Very  possibly  the  above  estimate  exaggerates  the  mortality 
due   to  alcohol,  but  that  it  is  very  considerable  is  shown  by  the 
statistics   of  insurance   companies.     Thus   the   United   Kingdom 
Temperance  and  General  Provident  Institution,  the  policy-holders 
of  which  are  separated  as  sheep  from  goats  into  abstainers  and 
non-abstainers,  found  the  mortality  amongst  the  former  71.49  per 
cent,  of  the   total  expected,  whereas  amongst   the  latter  it  was 
96.66  per  cent.     In  the  Sceptre  Life  Office  the  percentage  was 
56.86  and  77.61.     On  the  average  the  members  of  the   Friendly 
Society  of  Rechabites,  who  are  abstainers,  live  longer  and  have  less 
sickness  than  Oddfellows  and  Foresters.     The  mortality  amongst 
grocers  has  increased  appreciably  since  they  were  permitted  to  sell 
wine  and   spirits.     English  and    Russian  soldiers,   who  consume 
considerable  quantities  of  alcohol,  perish  more  readily  of  wounds 
than    Afridis    and  Turks,  who  consume   little  or  none.     Heavy 
drinkers  tend  to  fall  into  poverty,  the  slums  of  our  cities  being 
full  of  them.     Their  children,  who,  if  they  survive,  tend  to  inherit 
their  characteristics,  perish  in  greater  numbers  than  the  offspring 
of  more  temperate  people.     Women  drinkers  are  often  immoral 
and  sterile. 

494.  Evidently  the  elimination    due   to  excessive   drinking  is 
much  greater  than  that  indicated  by  the  returns  of  the  Registrar- 
General,   so   much  greater   that  there  is   every  probability   that 
alcohol  is  an  agent  of  stringent   selection.     We  are  able  to  test 
this  conclusion ;  but,  first,  it  is  necessary  to  note  that  stringency 
of  alcoholic  selection  varies  with  time  and  place.     It  is  greatest 
when  and  where  drink  is  most  abundant  and  accessible,  and  the 
prevailing  social  tone  most  favourable  to  its  consumption.     Thus 
alcohol  is  more  accessible  to  Italians  than  to  Englishmen  and  a 
fortiori  to  Red  Indians  ;  to  coal-porters  more  than  to  coal-miners. 

The  social  tones  prevailing  during  the  Victorian  era  and  the 
Commonwealth  were  less  favourable  to  its  consumption  than  those 
which  prevailed  during  the  period  of  the  Georges  and  of  the  Restora- 

1  Collective  Investigation  Committee  of  the  British  Medical  Association. 
*  Alcohol  and  Public  Health,  by  J.  J.  Ridge,  M.D.     London  :  H.  K.  Lewis. 


THE  EVOLUTION  AGAINST  ALCOHOL  297 

tion.  It  is  less  favourable  amongst  clergymen  than  amongst 
publicans.  All  this  is  very  obvious  and  need  not  have  been 
mentioned  were  it  not  that  a  confused  notion  seems  prevalent 
amongst  writers  on  the  subject  that  selection  is  not  selection  if  it 
varies  in  intensity.  Selection  is  selection,  no  matter  what  its 
intensity.  It  may  not  be  stringent  enough  to  cause  progression, 
but  selection  it  is  nevertheless.  Again,  it  must  be  noted  that  the 
stringency  of  selection  is  not  to  be  estimated  by  the  magnitude  of 
the  mortality  due  to  the  selecting  agent,  but  by  the  greater  or  lesser 
completeness  with  which  it  weeds  out  the  unfit.  When  the  unfit 
are  very  numerous,  a  large  mortality  may  indicate  a  lesser  degree 
of  stringency  than  a  lower  mortality  when  the  unfit  are  less 
numerous.  For  example,  in  Italy,  where  people  are  '  naturally ' 
disinclined  to  excessive  indulgence,  and  where  alcohol  is  very 
abundant  and  accessible,  the  deaths  of  quite  a  few  excessive 
drinkers  may  indicate  a  greater  stringency  of  selection  than  the 
elimination  of  a  much  larger  number  in  England. 

495.  The  people  that  alcohol  eliminates  are  those  who  are  so  con- 
stituted mentally  that  they  are  tempted  to  take  it  in  excess.  There- 
fore "  the  tendency  of  evolution  is  to  produce  a  race  .  .  .  capable 
of  sitting  down  in  the  presence  of  floods  of  alcoholic  liquor  .  .  . 
without  the  desire  to  get  drunk."  x  Is  there  any  evidence  of  such 
an  evolution  ?  If  the  reader  will  call  to  mind  all  the  races  of  the 
world  of  which  he  has  a  knowledge,  he  will  find,  as  in  the  case  of 
a  prevalent  and  lethal  disease,  that  every  race  is  resistant  (i.e.  tem- 
perate] in  the  presence  of  alcohol  in  proportion  to  the  length  and 
severity  of  its  past  experience  of  the  poison.  There  is  no  exception 
to  this  rule.  Moreover,  whenever  we  possess  a  sufficiently  detailed 
and  prolonged  history  of  a  race  which  is  now  temperate,  we  find  that 
it  was  anciently  drunken.  To  this  rule  also  there  is  no  exception. 
Of  course,  however,  when  we  seek  to  compare  the  past  with  the 
present  of  a  race,  we  must  not  commit  the  absurdity  of  compar- 
ing one  year  or  decade  with  the  next  preceding  or  succeeding. 
Man  is  a  slow-breeding  animal  in  whose  race  germinal  changes 
occur  only  very  slowly,  and  the  extent  of  his  drinking  is  influenced, 
not  only  by  the  depth  of  his  desire,  but  by  many  other  considera- 
tions, such  as  the  accessibility  of  alcohol  and  the  tone  of  the  society 
in  which  he  is  reared.  Therefore  we  must  compare  past  eras  or 
centuries  with  much  later  times. 

1  Sir  E.  Ray  Lankester,  Fortnightly  Review,  Sept.  1896,  p.  413. 


CHAPTER  XVI 
THE  EVOLUTION  AGAINST  NARCOTICS 

Alcohol  in  ancient  and  modern  times — Among  the  lake-dwellers — In  Egypt 
— In  Greece — In  Italy — Among  Jews — In  West  Africa — In  Great  Britain — 
In  Germany — In  China — In  the  Western  Hemisphere — Opium — The  poisonous 
effects  of  narcotics — The  origin  of  the  susceptibility  to  the  charm  of  narcotics — 
Objections  to  the  theory  of  narcotic  evolution — Education — Strength  of  beverages 
— Civilization — The  memory  of  past  racial  disaster — Convivial  and  industrial 
drinking — The  alleged  effect  of  alcohol  on  the  germ-plasm. 


s 


496.  f^\  TRONG  solutions  of  alcohol  are  products  of  the  know- 
ledge and  skill  which  civilization  brings.  The  lowest 
savages,  for  example  the  Tierra  del  Fuegians  and 
Australians,  are  unacquainted  with  means  of  manufacturing  in- 
toxicating liquor.  Settled  tribes  almost  always  possess  intoxi- 
cants in  some  form,  alcoholic  or  other  ;  but,  unless  they  are  well 
advanced  in  civilization,  the  beverages  they  manufacture  are  weak 
and  far  from  abundant.  Thus  it  is  recorded  that  the  natives  of 
Guiana  were  obliged  to  drink  their  cassava  intoxicant  (which, 
however,  was  not  alcohol)  for  three  days  before  a  state  of  drunken- 
ness satisfactory  to  them  was  achieved.  Moreover,  especially  in 
cold  and  temperate  climates,  the  alcohol  made  by  savages  is 
usually  derived  from  the  fermentation  of  articles  of  food — milk, 
honey,  corn,  and  the  like — which  are  rarely  abundant  with  them. 
Owing,  then,  to  the  insufficiency  of  the  supply,  due  partly  to 
difficulties  of  manufacture  and  partly  to  lack  of  materials,  excessive 
drinking  amongst  most  savages  is  comparatively  rare  and  spas- 
modic. Consequently  the  elimination  of  the  unfit  is  far  from 
stringent.  But,  as  in  the  case  of  such  a  disease  as  tuberculosis, 
with  growing  civilization  comes  an  increasing  and  more  regular 
exposure  to  the  evil — in  other  words  an  increasing  and  more 
effective  stringency  of  selection.  It  follows  that  a  race  that  has 
evolved  its  own  civilization  or  very  slowly  absorbed  that  of 
another,  tends  to  become  resistant  to  alcohol  and  survive,  whereas 
a  race  which  is  suddenly  introduced  to  civilization  with  its  strong 
solutions  of  alcohol,  tends  to  drink  to  extinction. 

497.  Probably  in  all  the  world  alcohol  has  been  most  abundant 


ANCIENT  INTEMPERANCE  299 

and  uninterruptedly  accessible  in  the  vine-producing  countries  of 
the  South  of  Europe  and  the  forest  region  of  West  Africa.  There 
is  evidence  that  it  was  manufactured  from  wild  fruits  such  as  the 
raspberry  and  mulberry  by  the  lake-dwellers  of  Switzerland  and 
the  South  of  France  during  the  Stone  Age.  We  do  not  know  when 
the  vine  was  first  cultivated  for  alcohol,  but  the  fact  that  at  the 
dawn  of  myth  and  fable  grape-wine  was  in  use  all  round  the 
Mediterranean,  argues  an  immense  antiquity.  Probably  palm-wine 
has  been  used  in  West  Africa  and  elsewhere  for  almost  as  long. 
Both  the  vine  and  the  palm  enable  men  to  manufacture  abundance 
of  alcohol  without  trenching  on  their  food-supplies.  Just  as  we 
are  able  to  gather  little  from  history  about  the  endemic  diseases 
of  antiquity,  so  we  are  able  to  learn  little  about  its  endemic 
drunkenness.  Usually  the  earliest  references  relate  to  the  in- 
toxication of  some  prominent  person  on  some  memorable  occasion, 
and  then  the  reference  is  made,  not  because  the  person  was 
intoxicated,  but  because  the  occasion  was  memorable.  Thus  Noah 
is  represented  as  drunk  when  Ham  discovered  his  nakedness,  as 
was  Lot  when  he  became  the  ancestor  of  the  Moabites  and  the 
children  of  Ammon.  So  also  the  suitors  of  Penelope  were 
inflamed  with  wine  when  Ulysses  slew  them,  and  we  are  told  that 
Alexander  died  of  a  surfeit  of  drink.  Clearer  evidence  is  to  be 
gleaned  from  laws  and  injunctions  against  excessive  drinking, 
such  as  are  common  in  the  Old  Testament,1  and  of  which  many 
1  For  example,  "  Who  hath  woe  ?  Who  hath  sorrow  ?  Who  hath  contentions  ? 
Who  hath  babblings  ?  Who  hath  wounds  without  cause  ?  Who  hath  redness  of 
eyes  ?  They  that  tarry  long  at  the  wine.  They  that  go  to  seek  mixed  wine. 
Look  not  upon  the  cup  when  it  is  red,  when  it  giveth  colour  to  the  cup,  when  it 
moveth  itself  aright.  At  last,  it  biteth  like  a  serpent,  it  stingeth  like  an  adder  " 
(Prov.  xxiii.  29-32).  "  Woe  unto  him  that  giveth  his  neighbour  drink,  that 
puttest  the  bottle  to  him,  and  makest  him  drunken  also."  "  Blessed  art  thou, 
O  land,  when  thy  king  is  the  son  of  nobles,  and  thy  princes  eat  in  due  season,  for 
strength,  and  not  for  drunkenness  "  (Eccles.  x.  17).  "  Woe  unto  them  that  rise  up 
early  in  the  morning  that  they  may  follow  strong  drink,  that  continue  until  night 
till  wine  inflame  them  "  (Isa.  v.  1 1).  "  Woe  to  the  crown  of  pride  to  the  drunkards 
ofEphraim  .  .  .  that  are  overcome  with  wine  "  (Isa.  xxviii.  i).  "  But  they  also 
have  error  through  wine,  and  through  strong  drink  are  out  of  the  way  ;  the  priest 
and  the  prophet  have  erred  through  strong  drink,  and  they  are  swallowed  up  of 
wine,  and  they  are  out  of  the  way  through  strong  drink :  they  err  in  vain,  they 
stumble  in  judgment.  For  all  tables  are  full  of  vomit  and  filthiness,  so  that  there 
is  no  place  clean  "  (Isa.  xxviii.  7-8).  Jews  have  still  a  feast,  that  of  Purim,  when 
intemperance  is  not  only  permissible  to  them,  but  is  absolutely  encouraged. 
Modern  Jews  show  no  disposition  to  avail  themselves  of  the  permission  ;  but 
anciently  it  was  different.  "  We  need  only  mention  the  Purim,  or  deliverance 
of  the  Jews  from  the  rage  of  Haman,  which,  until  the  reign  of  Theodosius,  was 
celebrated  with  insolent  triumph  and  riotous  intemperance  "  (Gibbon,  The  Decline 
and  Fall  of  the  Roman  Empire,  vol.  ii.  p.  85,  ed.  Grant  Richards,  1903). 


300  THE  EVOLUTION  AGAINST  NARCOTICS 

are  addressed  to  races  which  are  now  so  temperate  as  not  to  need 
exhortation.  The  oldest  known  Egyptian  papyrus,  which  comes 
to  us  from  an  antiquity  of  7000  years,  contains  such  an  injunction, 
which  is  repeated  in  many  later  writings.  "  The  moralists  reprove 
these  excesses,  and  cannot  find  words  strong  enough  to  express 
the  danger  of  them.  Wine  first  loosens  the  tongue,  even  wresting 
from  him  dangerous  words,  and  afterwards  it  prostrates  him,  so 
that  he  is  no  longer  capable  of  defending  his  own  interests.  Do 
not,  therefore,  forget  thyself  in  the  breweries  ;  be  afraid  that  words 
may  come  back  to  thee  that  thou  hast  uttered,  without  knowing 
that  thou  hast  spoken.  When  at  last  thou  fallest,  thy  limbs  failing 
thee,  no  one  will  help  thee,  thy  boon  companions  will  leave  thee, 
saying,  '  Beware  of  him,  he  is  a  drunkard.'  Then  when  thou  art 
wanted  for  business  thou  art  found  prone  on  the  earth  like  a  little 
child." l  "  Young  men  especially  should  avoid  this  shameful  vice, 
for  beer  destroys  their  souls.  He  that  abandons  himself  to  drink 
is  like  an  oar  broken  from  its  fastening,  which  no  longer  obeys  on 
either  side ;  he  is  like  a  chapel  without  its  god,  like  a  house  with- 
out bread,  in  which  the  wall  is  wavering  and  the  beam  shaking. 
The  people  he  meets  in  the  street  turn  away  from  him,  for  he 
throws  mud  and  hoots  after  them  till  the  police  interfere  and  carry 
him  away  to  regain  his  senses  in  prison."  2 

498.  The  fact  that  the  Spartans  made  drunken  their  helots  that 
they  might  serve  as  "  awful  examples "  to  the  aristocratic  youth 
is  clear  evidence  of  the  danger  and  probably  the  prevalence  of 
drunkenness  amongst  the  latter.     Lycurgus  amputated  the  legs  of 
drunkards  and  destroyed  the  vines.     Solon  condemned  an  Archon 
to  death  for  being  drunk.     The  Senate  of  Areopagus  punished 
men  for  too  prolonged  drinking.     Pittacus  of  Mytelene  inflicted 
double  punishments    for    offences  committed    in    drink.     It    is 
related  that  thirty-six  competitors  perished  in  one  of  Alexander's 
drinking  matches.     The  festivals  in  honour  of  Dionysus  "  became 
more  and  more  dissolute  both  in  Greece  and  Rome  until  they 
degenerated  into  saturnalia  of  the  most  disgraceful  character."3 
Drunkenness  is  a  constant  theme  of  Homer  and  Aristophanes. 

499.  Apparently   alcohol   was   not   abundant   in    Italy    when 
Rome  was  founded,  for  "  Numa,  the  successor  of  Romulus  .  .  . 
directed,  from  the  great  scarcity  of  wine  that  prevailed,  that  no 
man  should  besprinkle   the  funeral  pile  with  it,   and  when   the 

1  The  Maxims  of  Ant,  XVIII.  Dynasty,  about  1530-1330  B.C. 
a  Maspero.  Life  in  Ancient  Egypt,  translated  by  A.  Morton,  p.  31. 
3  Samuelson,  History  of  Drink,  pp.  75-9. 


ITALIANS  AND  JEWS  301 

sacrifices  to  the  gods  were  permitted  in  wine,  it  was  declared,  with 
a  view  to  encourage  the  plantation  of  vineyards,  that  all  wine  so 
offered  should  be  the  produce  of  such  vine  plants  as  had  been  cut 
and  pruned."  1  The  elder  Pliny,  Petronius,  and  other  historians  of 
later  Roman  times,  mention  great  excesses.  The  sobriety  of  the 
modern  inhabitants  of  the  vine  countries,  including  Jews,  who  until 
lately  dwelt  mainly  in  the  warmer  parts  of  Europe,  is  well  known. 
For  example,  until  lately,  the  Italian  peasants  drank  at  their 
taverns,  for  a  very  trifling  sum,  by  the  hour,  not  by  the  quantity. 
A  publican  who  adopted  such  a  custom  among  Englishmen  would 
be  ruined,  amongst  Red  Indians  he  would  be  murdered.  An 
English  physician  resident  in  Italy  writes — 

500.  "  I  have  met  time  after  time  Italians  who  confess  without 
shame  that  they  have  never  drunk  anything  but  wine;  they  are 
never  drunken.     Drunkenness  upon  Italian  wine  I  have  seen,  but 
only  amongst  my  fellow-countrymen   and  women.      Among  my 
servants   I  find  that  water  as  a  drink  is  considered  bad  for  the 
stomach,  and  is  feared  just  as  water  in  a  bath  is  feared,  as  a  peril 
and  a  danger.  .  .  .  On  inquiry  from  old  residents  in  the  country  I 
learn  that,  however  abundant  the  vintage,  the  contadini  preserve 
always  their  temperate  habits,  drinking  their  fill,  but  never  becom- 
ing drunken.     Drunkenness  in  the  British  sense  is  so  very  rare  as 
to  be  a  matter  of  great  interest  and  discussion  when  it  occurs  ;  .  .  . 
even  thirty  years  ago,  when  the  export  trade  was  practically  nil, 
and  there  was  a  great  excess  of  production  over  consumption,  there 
was  no  drunkenness.     In  those  days,  I  am  told,  wine  was  given  to 
horses,  and  whole  barrels  would  be  poured  out  in  the  road  to  make 
way  for  the  new  vintage,  when  the  price  was  only  a  few  coppers 
per  flask  ;  ...  it  is  given  to  infants,  children  drink  it  regularly,  and 
babies  are  bathed  in  it,  but  drunkenness  in  the  English  sense  does 
not  exist."2 

501.  The  sobriety  of  modern  Jews  has  been  the  subject   of 
numerous  homilies.     In  London,  for  example,  a  drunken  Jew — or 
Italian  organ-grinder — is  practically  unknown.     Hebrew  sobriety 
is  often  attributed  by  the  members  of  that  community  to  "the 
fact,    recognized  by  many  non-Jews,  that  the  absence  of  drunken- 
ness amongst  Jews  is,  in  the  main,  due  to  their  training,  from  their 
earliest  childhood,  in  the  principles  of  their  religion,  which,  amongst 
other  things,  inculcates  temperance  and  moderation  in  all  things." 
The   Jews   have  the  reputation  of  being   as  much   addicted   to 

1  Morewood,  History  of  Inebriating  Liquors,  p.  u. 

*  Dr  H.  Laing-Gordon,  British  Journal  of  Inebriety,  Jan.  1904. 


302  THE  EVOLUTION  AGAINST  NARCOTICS 

pleasure  as  other  races,  and  Jewish  abstainers  are  almost  as  rare 
as  Jewish  drunkards.  If,  then,  Jews  are  temperate  only  through 
self-restraint,  they  must  all  be  under  the  influence  of  that  dire 
craving  which  the  toper  feels,  but  must  very  bravely  resist  it.  I  do 
not  know  if  it  is  possible  for  anyone  to  believe  this.  Moreover, 
the  claim  of  superior  moral  training  carries  a  corollary.  The 
Hebrew  moral  code  inculcates  a  good  deal  besides  sobriety — the 
Ten  Commandments,  for  example.  It  will  hardly  be  maintained 
that  Jews  are  as  conspicuously  superior  to  the  English,  for  instance 
in  morals  in  general,  as  they  are  in  sobriety.  If,  then,  Jews  are  so 
teachable  and  so  well  taught  as  to  be  sober  mainly  through 
religious  training,  must  we  conclude  that  their  religious  training  is, 
speaking  comparatively,  conspicuously  lax  and  faulty  with  regard 
to  morals  in  general?  This  inference  flows  logically  from  the 
Jewish  claim,  but  no  Jew  will  care  to  press  it.  Notwithstanding 
the  fulminations  in  the  Old  Testament,  some  Jews  maintain  that 
their  race  has  always  been  temperate.  But,  whether  we  trace 
their  descent  from  Noah  or  the  savages  of  the  Stone  Age,  we  arrive 
at  an  ancestry  actually  or  potentially  drunken.  What  caused  the 
change  of  type  ?  The  only  real  alternative  to  miracle  is  Natural 
Selection. 

502.  Palm  wine  is  cheap  and  plentiful  in  West  Africa,  but  it  is 
customary  at  missionary  meetings  to  represent  the  natives  as 
debauched  by  the  European  liquor  traffic.  However,  evidence 
to  the  contrary  is  not  lacking.  "My  business  is  to  state  facts, 
not  to  reconcile  those  facts  with  the  representations  or  fancies 
of  any  other  person.  .  .  .  The  phrases  that  '  liquor  is  a  great 
scourge  to  the  natives  of  this  country,'  that  it 'commits  great 
ravages '  and  *  possesses  extraordinary  power  over  the  people,'  are 
not  true.  .  .  .  The  last  phrase  is  certainly  applicable  to  Great 
Britain,  but  not  to  West  Africa,  .  .  .  The  whole  subject  of  the 
attitude  of  philanthropists  towards  liquor  in  this  country  is  of 
intense  interest  to  the  philosopher.  .  .  .  Therefore  understand  that 
in  my  humble  opinion  the  future  of  the  people  of  this  country  is 
not  in  any  danger  from  liquor.  One  would  like  to  be  able  to  say  as 
much  for  Great  Britain,  and  of  her  nearest  neighbour,  to  which 
nations,  in  the  natural  and  logical  course  of  circumstances,  temper- 
ance advocates  should  be  sent  from  this  country."  1 

1  "  Extract  from  a  speech  on  the  Liquor  Question  delivered  by  Sir  W. 
MacGregor,  K.C.M.G.,  in  Legislative  Council,  on  the  i6th  Oct.  1901,  and  re- 
published  for  general  information." — Southern  Nigeria  Government  Gazette,  Sept. 
9th,  1908,  p.  1285. 


THE  SOBRIETY  OF  WEST  AFRICANS  303 

503.  "  The  Honourable  Mr  Sapara  Williams  :  '  I  rise  to  support 
the   remarks   which    have    been    made   by  His    Excellency    the 
Governor   relative   to  the  extracts   which  he  has  read  from  the 
speech  delivered  by  Bishop  Tugwell  before  the  Native  Races  and 
the    Liquor    Traffic   Committee,    and   published   in    the   Diocesan 
Magazine  of  the  Western  Equatorial  Africa  for  July  1908.     I  have 
read  the  speech  as  published,  and  standing  here  as  an  Unofficial 
Member   of  Council,  I  am  bound  to  say  that  it  is   the  duty  of 
this  Board  to  take  special  notice  of  the  same  and  to  denounce  the 
utterances  therein  contained.      Every  one  knows  that   I    am   an 
abstainer  and  one  who  is  entirely  opposed  to  the  evils  of  intemper- 
ance ;    but   that   fact  does   not  impose   on  me  the  obligation  to 
shut  my  eyes  to  facts  in  order  to  endorse  these  false  statements  of 
the  Bishop.' "  * 

504.  "  I  do  not  say  that  every  missionary  who  makes  untrue 
statements  on  this  subject  is  an  original  liar ;  he  is  usually  only 
following   his  leaders   and    repeating   their   observations   without 
going  into  the  evidence  around  him.  ...  I  have  no  hesitation  in 
saying  that  in  the  whole  of  West  Africa,  in  one  week,  there  is  not  one 
quarter  the  amount  of  drunkenness  you  can  see  any  Saturday  in  a 
couple  of  hours  in  the  Vauxhall  Road,  and  you  will  not  find  in  a 
whole  year's  investigation  on  the  Coast  one-seventh   part  of  the 
evil,  degradation,  and  premature  decay  you  can  see  any  afternoon 
you  choose  to  take  a  walk  in  the  more  densely  populated  parts  of 
our  own  towns."  2 

505.  "  One  of  my  native  colleagues  also  gave   a  temperance 
address.     I  shall  not  soon  forget  the  earnestness  with  which  he 
exhorted   his  hearers  to  fight  the  gigantic  demon  strong   drink. 
*  For,'  said  he,  *  unless  we  put  forth  our  best  efforts  in  this  direction, 
there  is  a  danger  of  becoming  as  drunken  as  the  people  of  England.' 
This  was  a  rather  startling  way  of  putting  the  case,  but  it  was 
decidedly  refreshing,  as  I  remember  there  were  so  many  in  England 
who  appear  to  be  under  the  impression  that  whole  territories  are 
being  depopulated  by  the  importation  of  spirits.     The  statement 
expressed  by   my  colleague   was   forceful,    but    I    unhesitatingly 
endorse   it.  ...  A   friend    of  mine,   a   most   ardent  temperance 
reformer,  was  appointed  District  Commissioner  of  Cape  Coast  a 
few  months  prior  to  my  first  residence.     At  the  end  of  his  first 
term  of  service  he  took  the  opportunity  to  write  to  a  temperance 
paper  in  this  country  to  say  that  the  friends  of  temperance  would 

1  Op.  dt.,  p.  1283. 

a  Miss  Kingsley,  Travels  in  West  Ajnca,  pp.  492-5 


304  THE  EVOLUTION  AGAINST  NARCOTICS 

be  glad  to  know  that  the  ravages  of  the  drink  traffic  were  not  so 
serious  at  the  Gold  Coast  as  was  generally  supposed.  Out  of  the 
hundreds  of  cases  tried  at  his  court  during  the  twelve  months,  not 
one  was  traceable  to  the  abuse  of  strong  drink." l 

506.  "  But  what  are  the  facts  of  the  case  ?     The  author  has  for 
many  years  been  favourably  situated  for  ascertaining  the  condition 
of  affairs  in  Africa.     He  has  conversed  with  men  of  culture  who 
have  resided  for  many  years  on  the  coast  at  various  places  of  trade, 
and  the  consensus  of  opinion  as  well  as  the  facts  that  have  been 
narrated    to   him    point   to   a  widely   different   conclusion.     The 
exportation  of  strong  drink  from  England  to  the  West  Coast  of 
Africa  is  enormous.     It  chiefly  consists  in  rum  ;  and  by  far  the 
larger  portion  of  this  is  forwarded  into  the  interior,  and  is  drunk 
out  of  sight  amongst  the  savage  tribes  who  are  rarely  visited  by 
Europeans."2 

507.  The    ancient   Germans   were    exceedingly    intemperate. 
According  to  Tacitus,  "  intemperance  proves  as  effectual  in  subduing 
them  as  the  force  of  arms."     "  They  gloried  in  passing  whole  days 
and  nights  at  the  table ;  and  the  blood  of  friends  and  relations 
stained  their  numerous  and  drunken  assemblies.  .  .  .  Strong  beer, 
a  liquor  extracted  with  very  little  art  from  wheat  or  barley,  and 
corrupted  (as  it  is  strongly  expressed  by  Tacitus)  into  a  certain 
semblance  of  wine,  was  sufficient  for  the  gross  purposes  of  German 
debauchery.     But  those  who  had  tasted  the  rich  wines  of  Italy, 
and  afterwards  of  Gaul,  sighed  for  that  more  delicious  species  of 
intoxication.     They  attempted,  not,  however  (as  has  since  been 
executed  with  so  much  success),  to  naturalize,  the  vine  on  the  banks 
of  the  Rhine  and  Danube ;  .  .  .  The  intemperate  thirst  of  strong 
liquors  often  urged  the  barbarians  to  invade  the  provinces  on  which 
art   or  nature  had  bestowed  those  much   envied  presents.     The 
Tuscan  who  betrayed  his  country  to  the  Celtic  nations  attracted 
them  into  Italy  by  the  prospect  of  the  rich  fruits  and  delicious  wines, 
the  productions  of  a  happier  climate.     And  in  the  same  manner  the 
German  auxiliaries,  invited  into  France  during  the  civil  wars  of 
the  sixteenth  century,  were  allured  by  the  promise  of  plenteous 
quarters  in  the  provinces  of  Champange  and  Burgundy.     Drunken- 
ness, the  most  illiberal  but  not  the  most  dangerous  of  our  vices,  was 
sometimes  capable,  in  a  less  civilized  state  of  mankind,  of  occasion- 
ing a  battle,  a  war,  or  a  revolution."  3 

1  Rev.  Dennis  Kemp,  Nine  Years  at  the  Gold  Coast. 

a  Samuelson,  History  of  Drink,  p.  9. 

3  Gibbon,  Decline  and  Fall  of  the  Roman  Empire,  vol.  i.  pp.  255-6. 


GERMANS,  BRITISH,  AND  CHINESE  305 

508.  "  After  the  establishment  of  Christianity  the  monks,  who 
needed  wine  for  sacramental  purposes,  introduced  the  cultivation 
of  the  grape  to  Gaul  and  Germany." l      Drunkenness   increased 
enormously,  both  amongst  men  and  women.2     German  intemper- 
ance became  "  a  byword  amongst  the  nations,  as  the  edict  of  Karl 
IV.  declared."3     The  papal  official  at  the  court  of  Frederic  III. 
wrote  to  his  master,  "  Nilhic  est  aliud  vivere  quern  bibere,"  4  "  Living 
here  is  nought  but  drinking."     So  plentiful  was  the  wine  that  a 
contemporary  rhyme  declares — 

"  In  fifteen  hundred  and  thirty-nine 
The  casks  were  valued  at  more  than  the  wine." 

People  of  all  classes  drank  the  whole  day  long  like  modern 
soakers.  "  Amongst  the  vices,"  said  a  preacher  in  Germany  in  the 
ninth  century,"  feasting  and  drunkenness  especially  reign,  since  not 
only  the  rude  and  vulgar  people,  but  the  nobles  and  powerful  of 
the  land  are  given  up  to  them.  Both  sexes  and  all  ages  have  made 
intemperance  into  a  custom  .  .  .  and  so  greatly  has  the  plague 
spread,  that  it  has  infected  some  of  our  own  order  in  the  priest- 
hood, so  that  not  only  do  they  not  correct  the  drunkards,  but 
become  drunkards  themselves."  5  Charlemagne  and  his  successors 
vainly  attempted,  by  means  of  numerous  edicts  and  laws,  to  control 
the  prevailing  intemperance.  At  the  present  day  modern  Germans 
and  Frenchmen  of  the  vine  regions  are  as  temperate  as  modern 
Greeks,  Italians,  and  Portuguese. 

509.  Great  Britain  has  always  been  intemperate,  and  has  sought 
as  long,  as  often,  and  as  vainly  as  Germany  to  cure  the  evil  by 
laws.     Though  the  vine  was  never  cultivated  to  any  considerable 
extent,  yet  alcohol  gradually  became  cheaper  and  more  accessible 
as  the  wealth  and  civilization  of  the  country  advanced.     British 
intemperance  reached  its  culmination,  therefore,  at  a  later  period 
than  that  of  Germany.     However,  since  the  eighteenth  century, 
when  men   got   "drunk  for  a  penny  and   dead   drunk   for   two 
pence,"  and  had  clean  straw  in  which  to  sleep  away  the  effects  for 
nothing,  it  has  steadily  diminished.     At  the  present  day,  though 
not  so  temperate  on  the  average  as  the  inhabitants  of  the   vine 
countries,  most  Englishmen  are  sober,  notwithstanding   the  fact 
that  they  are  not  abstainers. 

510.  At  the  present  time  the  Chinese  are  very  temperate  in  the 
use   of  alcohol.      The   teachings   of  Confucius   and   his   disciple 

1  Samuelson,  History  of  Drink,  p.  104.  *  Op.  cit.,  p.  109. 

3  Op.  cit.,  p.  112.  4  Op.  ctt.,  p.  112.  s  opm  Ctftt  pt  II4> 

20 


306  THE  EVOLUTION  AGAINST  NARCOTICS 

Mencius  contain  so  little  about  alcohol  that  it  is  probable  that 
there  was  little  excessive  drinking,  even  in  fifth  century  B.C. 
"  Whilst  the  princes  and  people  are  warned  against  voluptuousness 
and  extravagance,  we  seldom  find  drunkenness  referred  to  as  a 
dangerous  and  prevalent  vice."  x  But  in  the  "  Announcement  about 
Drunkenness,"  an  imperial  edict  believed  to  have  been  promulgated 
about  1116  B.C.,  it  is  stated  that  "our  people  have  been  greatly 
disorganized  and  lost  their  virtue,  which  can  be  traced  to  their 
indulgence  in  spirits."  "  Yea,  the  ruin  of  states  great  and  small "  is 
invariably  traced  to  the  same  cause,  the  use  of  spirits.2  Prince 
Fung,  to  whom  the  Announcement  is  addressed,  says,  "  The  people 
of  Yin  had  followed  the  example  of  the  sovereign,  and  the  vice  of 
drunkenness  with  its  attendant  immoralities  extensively  character- 
ized the  highest  and  lowest  classes  of  society.  .  .  .  The  disastrous 
consequences  of  drunkenness  are  strikingly  set  forth ;  he  is  called 
to  roll  back  the  flood  of  its  desolation  from  his  officers  and  people."3 

511.  The  furious  drinking  of  those  savages,  and  those  only, 
who   have   had   little   or   no   racial    experience   of  alcohol,    Red 
Indians,   Esquimaux,    Tierra    del    Fuegians,   Australasians,    and 
others,  is  too  well  known  to  need  description.     They  tend  to  drink 
themselves  to  death  at  a  single  bout.4     Often,  as  in  the  case  of  the 
ancient  Germans,  their  intoxication  is  accompanied  by  homicidal 
mania,  a  cerebral  effect  that  tends  to  procure  the  speedy  elimi- 
nation of  the  drinker,  and   in  its  extreme  forms  is  rarely  found 
amongst  peoples  that  have  long  used  alcohol. 

512.  The  facts  concerning  opium  are  very  similar.     It  has  been 
used  in  India  for  hundreds  of  years.     So  rarely  do  the  natives  of 
that  country  take  it  in  excess  that  none  of  the  scientific  witnesses 
who  appeared  before  the  late  Royal  Commission  on  Opium  had 
ever  seen  an  instance.     It  was  introduced  into  China  about  two 
centuries  ago   with    disastrous   consequences,  but   already   many 
Chinese  take  it  in  moderation.     In  Burma,  Polynesia,  and  Australia, 
where  it  was  introduced  within   the  memory  of  living  man,  the 
aborigines  take  it  in  such  excess  and  perish  of  it  in  such  numbers 
that  their  white  rulers  are  obliged  to  forbid  its  use  to  them,  while 
permitting  it  to  natives  of  India,  Chinese,  and  other  aliens — just  as 
in  Australasia  and  Canada  they  are  obliged  to  forbid  the  use  of 
alcohol  to  the  aborigines,  while  permitting  it  to  the  whites. 

513.  Narcotics,  like  most  diseases,  have  two  sets  of  poisonous 
• 

1  Samuelson,  History  of  Drink,  p.  19. 

2  Op.  cit.,  p.  20.  3  Op.  cit.,  p.  20. 

4  See  Alison's  History  of  Europe,  vol.  i.  p.  21,  seventh  edition. 


SECRETIONS  AND  EXCRETIONS  307 

effects,  the  immediate  and  the  remote.  The  former  are  those 
which  are  experienced  at  the  time  of  indulgence  or  within  a  short 
period  after,  and  are  due  mainly  to  the  direct  action  of  the  drug 
on  the  nervous  system.  Probably  the  earliest  effect  is  always  a 
greater  or  lesser  degree  of  paralysis,  which  besets  at  first  certain 
'inhibitory  centres'  of  the  brain,  and,  therefore,  may  present  in 
the  beginning  an  appearance  of  stimulation.  Thus,  after  a  small 
dose  of  alcohol  the  heart  tends  to  beat  faster,  owing  to  paralysis 
of  the  centres  which  inhibit  and  control  its  movements,  and  there 
may  also  be  mental  changes  involving  some  loss  of  self-control. 
A  deeper  degree  of  paralysis,  involving  other  nervous  centres, 
constitutes  obvious  intoxication.  This  initial  paralysis,  with  its 
associated  pleasurable  sensations,  is  exchanged,  some  hours  later, 
when  the  poison  is  eliminated  from  the  body,  for  the  well-known 
after-effects — the  temporary  illness  which  follows  a  bout  of 
excessive  indulgence.  The  remote  effects  are  mainly  gradual 
degenerative  changes  in  many  tissues,  including  the  brain.  As  a 
rule  they  do  not  occur  until  after  chronic  excessive  indulgence 
of  some  months,  or,  more  commonly,  years.  In  England  few 
deaths  occur  from  the  immediately  poisonous  effects  of  alcohol, 
but  amongst  Red  Indians  and  others,  whose  tendency  to  very 
deep  indulgence  is  greater,  they  are  more  common. 

514.  Alcohol  is  an  excretion,  a   waste-product   of  the   yeast 
fungus,  comparable  as  such  to  the  urine  or  carbonic  acid  excreted 
by  man.     Opium  and  nicotine,  on  the  other  hand,  are  real  toxins 
elaborated  by  the  poppy  and  tobacco  plants.     They  serve,  like  all 
other  vegetable  poisons  and  like  the  toxins  of  microbic  diseases,  as 
a  means  of  defence  against  enemies.    We  have  seen  that  an  acquired 
immunity  to  a  disease  is  a  capacity,  developed  under  the  stimulus 
of  use,  to  tolerate  a  toxin  which  was  previously  more  poisonous. 
We  have  seen,  also,  that  many  individuals   of  human  races  that 
have  had  no  previous  experience  of  measles  and  other  acute  lethal 
diseases,  are  able  to  acquire  immunity  against  them,  though  indi- 
viduals of  races  that  have  had  long  experience  are  able  to  acquire 
it  more  easily.    It  follows  that,  in  addition  to  having  evolved  special 
powers  of  acquiring  immunity  against  particular  diseases,  man  has 
evolved  a  general  power  of  becoming  able  to  tolerate  toxins,  which 
again  is  a  part  of  the  general  power  of  making  use-acquirements. 
Doubtless,  it  is  on  this  account  that  experience  makes  the  indi- 
vidual so  tolerant  of  opium  and  tobacco  that  he  is  able  to  consume, 
without  immediate  poisoning,  immensely  increased  doses. 

515.  But  no  amount  of  experience  enables  a  man  to  increase 


308  THE  EVOLUTION  AGAINST  NARCOTICS 

his  power  of  resisting  tuberculosis  nor  greatly  increases  his  power 
of  tolerating  alcohol.  That  is,  he  cannot  acquire  immunity  to 
the  former  nor  learn  to  take,  without  intoxication,  doses  of  the 
latter,  a  waste  product  (the  chemical  composition  of  which  is 
much  less  complex  than  that  of  the  toxins) l  a  hundred-  or  a 
thousand-fold  larger  than  those  which  were  immediately  poisonous 
to  him  at  the  beginning  of  his  experience.  Therefore,  in  the  case 
of  acute  diseases  and  opium  and  nicotine,  man  has  a  means  of 
protection  which  is  absent  in  the  case  of  alcohol  and  chronic 
complaints  such  as  tuberculosis.  Consequently  a  race  that  is  for 
the  first  time  introduced  to  an  acute  disease  or  to  nicotine  or 
opium  does  not  start  "  from  the  scratch."  It  is  advantageously 
situated.  It  has  undergone  a  previous  evolution  which,  by 
enabling  it  to  acquire  immunity,  places  it  in  a  position  of 
advantage.  In  the  case  of  tuberculosis  and  alcohol  it  has  to 
undergo  an  evolution  which,  in  each  instance,  must  be  begun 
almost  at  the  beginning.  Under  severe  modern  conditions,  the 
races  of  the  New  World  are  able  to  survive  acute  diseases  and 
undergo  evolution,  but  tuberculosis  exterminates  them.  There- 
fore, evolution  against  tuberculosis  is  much  the  more  difficult  and 
tedious.  Similarly,  evolution  against  alcohol  appears  to  be  more 
difficult  than  that  against  opium.  An  evolution  of  a  few  hun- 
dreds of  years  has  rendered  the  natives  of  India  '  immune '  to 
opium,  but  an  experience  of  thousands  of  years  has  rendered  the 
British  only  in  a  measure  immune  to  alcohol  in  the  sense  that 
Italians  are  immune  to  it. 

516.  Tobacco  may  be  compared  to  chicken-pox.     Nearly  all 
sufferers  quickly  and  easily  acquire  immunity  against  this  disease, 
and  all  tobacco-smokers  are  moderate  in  the  sense  that  they  do 
not  desire  to  reproduce  the  immediately  poisonous  effects  which 
they  felt  as  beginners.     So  few  people  perish  from  the  one  or  the 
other  that  no  evolution  results.    Therefore  races  that  have  long  been 
afflicted  by  chicken-pox  suffer  as  severely  as  races  that  are  newly 
exposed  to  it,  while  races  that  have  long  used  tobacco  indulge  in 
it  as  deeply  as  those  who  have  had  no  previous  experience. 

517.  Opium  may  be  compared  to  malaria.     Malaria  lies  mid- 
way between  tuberculosis  and  chicken-pox.     It  is  more  acute  than 

f~5  !  The  power  of  acquiring  a  toleration  does  not,  however,  depend  entirely  on 
the  chemical  complexity  of  the  toxin.  Thus,  while  it  is  said  to  be  possible  to 
increase  the  toleration  for  arsenic,  an  absolutely  simple  substance,  no  appreciable 
increase  of  toleration  follows  the  use  of  many  vegetable  toxins,  for  example 
digitalis  and  strychnine.  See  §  413. 


THE  MEANING  OF  "  IMMUNITY  "  309 

the  former  and  more  chronic  than  the  latter.  But  since  native 
West  Africans  suffer  more  from  it  as  children  than  as  adults,  and 
since  adult  negro  immigrants  from  non-malarious  countries  suffer 
more  at  first  than  the  native  adults  and  more  than  they  themselves 
do  later,  it  is  evident  that  individuals  of  a  race  that  has  long  been 
exposed  to  it  are  capable  of  acquiring  a  considerable  degree  of 
immunity.  Apparently,  average  Englishmen  gain  no  such  increase 
of  resisting  power.1  Nevertheless,  judging  from  the  direction  taken 
by  the  evolution,  it  is  probable  that  members  even  of  a  race  that 
has  had  no  previous  experience  have  some  power  of  acquiring 
resisting  power — a  power  which,  though  it  does  not  afford  much 
protection  to  a  majority  of  individuals,  yet  has  selection  value. 
Similarly,  opium  lies  midway  between  alcohol  and  tobacco.  The 
individuals  of  all  races  are  capable  of  increasing  their  power  of 
resisting  opium  ;  that  is  they  are  able  to  acquire  the  power  of 
taking  greatly  increased  doses  without  immediate  poisoning, 
without  intoxication.  But  individuals  of  races  that  have  long 
experienced  it  tend  to  take  it  in  less  excess,  tend  more  to  be 
satisfied  with  non-intoxicating  doses  than  races  to  which  the 
drug  is  new.  Experience  of  opium,  therefore,  tends  to  place  a 
race  in  the  same  position  of  advantage  that  it  occupies  from  the 
first  with  respect  to  tobacco. 

518.  It  should  be  noted  that  the  term  '  immunity/  when  applied 
to  microbic  diseases  and  to  narcotics,  has  not  identical  meanings. 
Immunity  to  disease  implies  a  physical  power  of  resisting  infection. 
Immunity  to  a  narcotic  is  a  mental  phenomenon  implying  such  an 
insusceptibility  to  its  charm  that  the  individual  is  not  tempted  to 
excessive  indulgence.     Nevertheless,  the  analogy  between  diseases 
and  narcotics  is  very  close. 

519.  We  see,  then,  that  alcohol  and  opium  act  as  agents  of 
selection  in  the  same  way  precisely  as  lethal  and  prevalent  diseases. 
They  eliminate  particular  types  of  individuals.     Individuals  differ 
in  their  susceptibility.     The  more  susceptible  are  eliminated  and 
as  a  consequence  the  race  undergoes  protective  evolution.     When 
thinking  of  narcotics,  the  reader  must  bear  in  mind  evolution  in 
general.      All    progressive     evolution   depends   on   selection,   all 
stringent  selective   elimination  results   in  evolution.      When  the 
whole  of  the  facts  are  taken  into  account  it  is  not  believable  that 
alcohol  and  opium,  which  are  so  enormously  destructive  of  life 
and  so  plainly  selective,  can  be  an  exception  to  the  rule.     It  has 
been  objected  that,  since  alcohol  awakens   unlike  sensations  in 

1  See  §  393. 


310  THE  EVOLUTION  AGAINST  NARCOTICS 

different  men,  thereby  causing  them  to  drink  for  diverse  reasons, 
it  does  not  eliminate  a  particular  type.  The  objection  is  merely 
verbal.  Whatever  the  shades  of  difference,  all  men  drink  because 
the  act  awakens  pleasurable  sensations — because  it  gives  actual 
pleasure  or  because  it  soothes  discomfort  or  suffering.  The  type 
which  survives  is  one  in  which  acute  pleasure  is  not  awakened  nor 
suffering  soothed  by  deep  indulgence.  It  would  be  as  reasonable 
to  argue  that  carnivora  are  not  causes  of  evolution  in  antelopes 
because  some  of  the  latter  are  eliminated  on  account  of  dull  hear- 
ing, others  for  defective  sight,  others  for  insufficient  speed,  and  so 
forth.  Nor,  as  we  have  seen,  is  the  argument  valid  that  selection 
is  not  selection  because  it  varies  in  intensity  with  time  and  place, 
and  is  never  absolutely  thorough.  Some  people  ask  how  the 
susceptibility  to  the  charm  of  narcotics  can  have  arisen  in  the 
human  race,  and  appear  to  think  that  they  have  indicated  a  valid 
objection.  Probably  it  is  a  by-product  correlated  to  mental  evolu- 
tion in  general — a  by-product  which  was  harmless  while  mind  was 
evolving,  and  only  became  injurious  when  men  discovered  that 
certain  vegetable  poisons  were  capable  of  producing  delightful 
sensations.  But  the  question  as  to  how  it  arose  is  one  thing.  The 
question  as  to  whether  it,  being  existent,  is  a  cause  of  selective 
elimination  is  quite  another  thing.  It  certainly  exists. 

520.  The  theory  that  alcohol  and  opium,  like  lethal  and  pre- 
valent diseases,  are  causes  of  protective  evolution,  is  so  opposed  to 
popular  notions  that  it  is  apt  to  be  received  with  initial  incredulity. 
I  can  only  beg  the  reader  to  test  the  chain  of  fact  and  reasoning 
link  by  link.  I  believe  that  he  will  conclude  ultimately  that,  if 
evolution  has  occurred  in  any  instance,  then  it  has  occurred  in  this 
instance  also.  Is  it  undeniable  that  men  differ  in  the  sensations 
awakened  in  them  by  alcohol  (and  opium)  ;  that  some  are  so  consti- 
tuted that  after  a  given  experience  they  are  much  more  tempted 
to  excessive  indulgence  than  others,  for  the  reason  that  their 
sensations  are  more  pleasurable  ;  that,  as  a  general  rule,  men  yield 
to  temptation  in  proportion  as  they  are  strongly  tempted  ;  that  the 
average  moderate  drinker  shows  no  indication  that  he  is  strongly 
tempted  to  deep  indulgence  ;  that  the  average  excessive  drinker 
shows  every  indication  that  he  is  so  tempted,  for  otherwise  no  one 
would  do  actions  so  painful  and  ruinous,  both  in  the  immediate  and 
remote  future ;  that  he  tends  to  transmit  his  degree  of  suscepti- 
bility to  descendants;  that  drink  tends  to  shorten  the  lives  of 
excessive  drinkers  and  otherwise  lower  the  number  of  their  possible 
descendants  ;  that  the  amount  of  this  elimination  is  large  j  that 


RACIAL  DIFFERENCES  3 1 1 

therefore  alcohol  is  an  agent  of  stringent  selection  ;  that  every  race 
on  earth  that  has  had  little  or  no  experience  of  alcohol  tends  to  be 
excessively  intemperate  when  afforded  the  opportunity ;  that 
therefore  this  excessive  susceptibility  is  the  primitive  condition  of 
humanity  ;  that  every  race  that  has  had  previous  experience  is  tem- 
perate in  the  presence  of  abundant  supplies  of  alcohol  in  proportion 
to  the  length  and  severity  of  its  experience  ;  that  therefore  there  is 
no  escape  from  the  conclusion  that  such  races  have  undergone 
protective  evolution  ?  The  subject  requires  careful  and  unprejudiced 
thought.  Hitherto  men  have  been  content  to  accept  without 
question  the  simple  belief  that  men  are  sober  or  intemperate  in 
proportion  as  they  do  or  do  not  exercise  self-control — a  belief 
which  involves  the  corollary  that,  since  drunkards  are  vehemently 
tempted,  therefore  all  moderate  men  are  as  much  tempted  but  oppose 
even  more  vehement  resistance.  The  reader  should  test  this  hypo- 
thesis by  examining  his  own  psychology  and  that  of  his  intimates. 

521.  Formerly  it  was  universally  believed  that  certain  races 
(e.g.  Italian  and  Spanish)  were  'naturally'  more  temperate  than 
others  (e.g.   English  and  Red   Indian).     But  since  the  theory  of 
alcoholic  evolution  was  formulated,  the  surprising  discovery  has 
been    made   that   the   races   hitherto   supposed    to   be    the   most 
temperate  are  really  the  most  drunken  of  all.     Thus  it  is  stated 
that  the/w  capita  consumption  in  the  South  of  Europe  is  greater 
than  in  the  North,  and  much  greater  than  among  Red  Indians  or 
Australian  blacks,  and  the  *  obvious '  inference  is  drawn  that  South 
Europeans  are  much  the  most  intemperate  of  all.     According  to 
this  theory,  if  a  party  of  one  hundred  men  consumed  two  bottles 
of  spirits,  each  man  taking  his  share,  while  one  member  of  a  party 
of  similar  strength  drank  a  whole  bottle  by  himself,  there  would  be 
twice  as  much  intemperance  in  the  former  party  as  in  the  latter. 
In  the  South  of  Europe  practically  every  man,  woman,  and  child 
takes  alcohol  ;    but   excessive  drinkers  are   rare.     In   the  North 
multitudes  of  men,  more   women,  and  nearly  all   children  take 
no  alcohol  at  all ;  multitudes  take  it  in  moderation  ;  but  a  con- 
siderable minority  are  excessive  drinkers.     The  Western  aborigines 
are   rarely   able   to   procure   alcohol ;    but,    when   they   have   the 
opportunity,  they  all  of  them  almost  invariably  take  it  in  excess. 

522.  Racial  differences  with  respect  to  alcohol  are  admitted 
by  most  people,  but  are  attributed  to  all  sorts  of  causes  other  than 
evolution.     Climate :  Since  South  Europeans  are  sober,  a  warm 
temperate  climate  has  been  thought  to  be  conducive  to  moderation. 
But  only  those  races  inhabiting  warm  temperate  climates  which 


312  THE  EVOLUTION  AGAINST  NARCOTICS 

have  undergone  prolonged  alcoholic  selection  are  moderate.  All 
the  rest,  for  example  Andamanese,  Red  Indians,  Polynesians,  and 
Australasians,  are  very  drunken.  Jews  and  South  Europeans  are 
temperate  in  all  the  climates  to  which  they  migrate.  West  Africans 
are  temperate  in  the  torrid  zone. 

523.  Education^  and  general  mental  training.  What  is  there  in 
the  education  of  Jews  and  South  Europeans  that  should  render 
them  more  capable  of  exercising  self-control  than  North  Europeans? 
The  upper  classes  in  England  and  elsewhere  amongst  civilized 
races  are  supposed  to  be  better  trained  mentally  than  the  lower. 
Certainly  they  have  more  information  derived  from  reading  and 
are  also  less  inclined  to  excess.  But  the  upper  classes  of  the 
present  day  are  in  general  derived  from  those  of  former  times,  and 
therefore  are  precisely  the  classes  which  have  had  the  greatest 
command  of  alcohol,  and  have  been  most  weeded  out  by  it. 
Recruits  from  lower  to  higher  classes  are  almost  always  tem- 
perate people ;  contrariwise  intemperance  has  lowered  many 
families  from  a  higher  to  a  lower  stratum.  There  has  been, 
in  this  particular  instance,  a  process  of  Social  as  well  as  Natural 
Selection.  It  must  be  remembered  that  though  education  may 
create  a  moral  abhorrence,  it  cannot  alter  sensations  —  neither 
those  created  by  alcohol,  nor  tobacco,  nor  salt,  nor  sugar,  nor 
anything  else.  The  sensations  created  by  excessive  indulgence  in 
a  majority  of  people  in  the  upper  classes  are  apparently  different 
from  those  experienced  by  many  in  the  lower,  in  that,  on  the 
average,  they  are  so  much  less  pleasurable  that  they  awaken  desires 
which  are  very  much  less  keen.  Poverty  and  its  accompaniments, 
hardship,  want,  overcrowding,  dirt,  insanitation,  and  lack  of  in- 
tellectual pleasures  are  supposed  to  conduce  to  the  intemperance 
of  our  poorer  classes.  Doubtless  they  do,  but  to  a  very  limited 
extent.  Under  similar  or  worse  conditions,  for  instance  in  the 
East  End  of  London,  Jews  and  Italians  are  extremely  temperate. 
In  their  own  countries  the  lower  classes  of  South  Europeans  are 
as  temperate  as  the  upper.1  The  fact  that  South  Europeans  (e.g. 
Italians  and  Spaniards)  living  in  cities  or  engaged  in  manufactories, 
tend  to  be  more  intemperate  than  their  rural  compatriots,  has  been 
supposed  to  demonstrate  the  influence  of  the  environment  (i.e. 
mental  training)  as  against  that  of  heredity.  But  the  influence  of 
the  environment  has  been  denied  by  no  one.  It  is  maintained 

1  It  is  interesting  to  note  that  while  the  intemperance  of  the  English  lower 
classes  is  often  attributed  to  their  poverty,  the  comparative  sobriety  of  the  poorer 
Chinese  has  been  assigned  to  the  same  cause  (see  History  of  Drink,  p.  32). 


ALLEGED  CAUSES  OF  INTEMPERANCE  313 

merely  that  the  degree  to  which  any  individual  indulges  depends 
on  the  interaction  of  two  factors,  one  of  which  (susceptibility) 
is  innate,  and  the  other  of  which  is  environmental.  Proof  that  the 
environment  is  influential  is  not  proof  that  innate  susceptibility  has 
no  influence.1  It  is  known  that  when  men  are  gathered  together  in 
large  numbers  in  cities  or  manufactories  they  tend,  owing  to  the 
relative  lack  of  restraint,  to  be  more  intemperate  in  every  way  than 
when  living  in  the  country.  The  question,  therefore,  is  not  whether 
the  individuals  of  the  same  race  are  more  intemperate  in  one 
environment  than  in  another,  but  whether,  when  individuals  or 
races  are  placed  under  conditions  that  are  practically  identical, 
the  one  individual  or  race  tends  to  be  more  intemperate  than  the 
other.  Compare,  for  example,  Italian  peasants  with  English 
peasants,  and  Italian  ice-vendors  and  organ-grinders  in  London 
with  English  street  musicians  and  costers. 

524.  Strength  of  beverages.     Races  are  supposed  to  be  drunken 
or   temperate   according  to   the   strength  of  the  beverages   they 
consume.     No  doubt  a  man  who  desires  to  get  drunk  will,  as  a  rule, 
if  he  have  the  opportunity,  choose  a  strong  solution  of  alcohol, 
whereas  one  who  is  prompted  mainly  by  thirst  or  taste  will  select 
a  more  dilute  and  palatable  drink.     But  it  is  quite  as  possible  to 
get  drunk  on  a  weak  as  a  strong  solution,  and  it  is  done  very  often. 
More  Englishmen  are  intemperate  on  beer  than  on  spirits,  and 
on  the  average  their  alcohol  is  twice  or  thrice  as  dilute  as  the 
wine  of  South  Europeans.2     Those  savages  who  are  able  to  manu- 
facture only  very  dilute  solutions — or,  indeed,  no  alcohol  at  all — 
are  the  most  drunken  people  on  earth  when  opportunity  offers. 

525.  Civilization  is  supposed  to  conduce  to  moderation.    This  is 
certainly  true,  but  not  for  the  reason  implied.     North  Europeans 
are  more  civilized  than  South  Europeans  and  West  African  savages, 
but  more  drunken.    Civilization  has  always  implied  abundance  of 
alcohol.     Therefore  all  races  capable  of  living  under  civilized  condi- 
tions have  undergone  alcoholic  evolution.    The  incapacity  of  Red 
Indians  to  resist  alcohol  is  as  much  a  bar  to  their  survival  under 
modern  conditions  as  their  inability  to  withstand  tuberculosis. 

526.  The  memory  of  past  disasters.     Races,  like   the  Italians, 
which  have  suffered  much — two  or  three  thousands  of  years  ago — 
are   supposed  to  bear  in  mind   so   keen    a   recollection    of  their 
miseries  that  they  are  now  temperate  in  consequence.     Whereas 
races  like  the  English  who  have  suffered  less — but  who  are  now 

1  See  §  693. 

8  See  The  British  Medical  Journal,  i5th  Dec.  1900,  p.  1733. 


314  THE  EVOLUTION  AGAINST  NARCOTICS 

suffering,  and  for  two  or  three  thousands  of  years  have  been 
suffering,  are  supposed  to  be  proportionately  less  aware  of  the 
dreadful  results  of  intemperance,  and  on  that  account  to  be  more 
drunken.  The  existence  of  a  temperance  propaganda  and  of 
prohibitory  laws  amongst  North  Europeans  and  their  colonists, 
and  the  absence  of  them  amongst  South  Europeans,  is  a  fit  com- 
mentary on  this  shocking  nonsense. 

527.  Convivial  and  industrial  drinking  are  terms  which  have 
been  applied  to  indulgence  occurring  during  leisure  and  work  time 
respectively.  Other  things  equal,  men  drink,  smoke,  play  cricket, 
or  indulge  themselves  in  any  other  way  in  proportion  to  their 
desires.  One  of  the  "  other  things  "  is  opportunity  for  indulgence, 
which  varies  with  time,  place,  and  occupation.  Thus  I  have  two 
occupations,  medicine  and  authorship.  I  smoke  a  great  deal  when 
I  am  writing,  but  not  at  all  when  I  am  attending  to  sick  people. 
So  also  a  judge  or  preacher  smokes  less  during  the  performance  of 
his  duties  than  the  average  gardener.  A  coal-miner  is  forbidden 
under  the  severest  penalties  to  smoke  or  drink  during  his  working 
hours.  He  is  even  searched  before  descending  into  the  pit.  A 
coal-porter  on  the  other  hand,  is  restrained  from  immoderate 
indulgence  in  alcohol  only  by  expense  and  the  fear  of  the  police. 
It  does  not  require  a  very  high  degree  of  intelligence  to  conclude 
that,  other  things  equal  (e.g.  a  desire  for  alcohol),  the  average 
porter  will  consume  more  during  his  working  hours  than  the 
average  judge  or  miner.  Again,  some  occupations  demand  delicate 
manipulative  skill,  others  nothing  more  than  violent  muscular 
effort.  The  imbibition  of  a  quantity  of  alcohol  which  interferes 
little,  if  at  all,  with  the  latter,  spells  inefficiency  in  the  case  of  the 
former.  For  example,  a  watchmaker  or  engraver  will  become 
incapable  on  smaller  quantities  of  alcohol  than  a  dock-labourer  or 
market-porter.  As  a  consequence,  others  things  equal,  skilled 
workers  tend — if  only  by  the  dropping  out  of  the  incapables — to 
be  more  temperate  than  rough  labourers. 

528.  In  two  kinds  of  occupation,  then,  is  excessive  drinking 
during  working  hours  comparatively  rare — those  in  which  drink 
is  more  or  less  inaccessible  to  the  workman,  and  those  in  which 
it  quickly  renders  him  inefficient  Speaking  practically,  all 
'  industrial '  drinkers  are  *  convivial '  drinkers  also.  So  that  in 
effect  the  former  imbibe  all  day  long,  whereas  the  pure  convivial 
drinker,  who  is  also  a  worker,  imbibes  only  in  the  evening.  Doubt- 
less it  often  happens  that  the  man  who  has  been  half  drunk 
previously  becomes  wholly  drunk  when  his  work  is  finished  and  he 


A  NEW  INTERPRETATION  315 

is  comparatively  free  from  restraint.  Consequently,  as  might  be 
expected,  industrial  soakers  consume  more,  and  therefore  suffer 
more,  than  merely  convivial  drinkers.  In  point  of  fact,  occupations 
in  which  industrial  drinking  is  easily  possible  show  higher 
proportions  of  illness  and  death  from  excessive  indulgence  than 
occupations  in  which  it  is  difficult  or  impossible. 

529.  In  every  occupation,  even  the  coarsest,  excessive  drink- 
ing, owing  to  the  expense  and  loss  of  efficiency,  is  a  bar,  and  is 
universally  known  to  be  a  bar,  to  success.     If,  then,  a  man,  in  spite 
of  pains  and  penalties — loss  of  health  and  efficiency,  liability  to 
dismissal  from  employment,  and  the  like — drinks  to  excess  during 
his  working  hours,  it  is  reasonable  to  conclude  that  he  is  greatly 
tempted  by  alcohol.     Indeed,  we  may  fairly  conclude  that  on  the 
average  such  a  one  is  more  susceptible  to  its  charm,  more  tempted 
by  it,  than  his  fellow  who  abstains  from  prudential  motives  and 
drinks  only  in  the  evenings  when  he  is  at  leisure.     That,  at  any 
rate,  I  think,  is  the  conclusion  which  ninety-nine  people  of  normal 
intelligence  out  of  a  hundred  would  reach.     But  a  belief  that  men 
drink  alcohol   for  enjoyment  and  that   individuals   vary   in   the 
degree  and  kind  of  enjoyment  conferred  by  it  leads  inevitably  to 
a  theory  of  alcoholic  selection,  a  conclusion  greatly  disliked  by  many 
people,  especially  temperance  enthusiasts.     Recently,  therefore,  a 
new  interpretation  of  the  facts  has  been  formulated,1  a  considera- 
tion of  which  will  at  any  rate  serve  to  demonstrate  the  dreadful 
kind  of  thinking  which  finds  favour  with  many  earnest  reformers. 
We  are  told,  in  effect,  that  it  is  absurd  to  suppose  that  men  differ 
in  the  degree  in  which  they  are  tempted  by  alcohol. 

530.  "  It  has  led  some  less  responsible  students  of  the  question 
to  assume  that  the  view  conveniently  expressed  in  the  formula, 
that  inebriety  is  a  symptom  of  disease  offers  a  complete  and  valid 
explanation  of  all   the   facts   of  alcoholism.     Thus  it   has   been 
asserted  that  intemperance  is  always  a  manifestation  of  a  definite 
brain  condition  which  creates  a  specific  craving  for  alcohol.     And 
some  enthusiasts  have  even  gone  further,  and,  assimilating  this 
hypothetical  drink-crave  to  a  peculiarity  of  anatomical  structure, 
have  regarded  the  potentiality  of  being  a  drunkard  as  a  simple 
inborn  trait,  which,  we  are  gravely  assured,  being  clearly  unfavour- 
able  to   its  possessor,  must   secure   his  early  elimination  in  the 
struggle  for  existence,  and  so  lead  through  natural  selection  to  the 
evolution  of  a  race  immune  from  drink  ! 

1  See,  for  example,  Alcoholism,  by  W.  C.  Sullivan,  M.D.     London :    James 
Nisbet  &  Co. 


316  THE  EVOLUTION  AGAINST  NARCOTICS 

531.  "Extravagances   of    this    sort,    apart   from    such    direct 
error  as  they  may  engender,  are   likely  to   have   a   mischievous 
influence,  in  that  they  divert  attention   from   the  real  biological 
aspects  of  the  question,  and  make  an  unnatural  divorce  between 
the  organic  and  social  causes  of  alcoholism,  which,  as  we  have 
already  pointed    out,   can   only  be   understood    in   their  mutual 
relations. 

532.  "For  the  proper  apprehension  of  the  question  we  must, 
therefore,  at  the  outset  get  rid  of  this    figment   of  an   inebriate 
diathesis  and  replace  it  by  the  rational  view,  that  the  explanation 
of  inebriety  is  to  be  sought,  not  in  any  specific  tendencies  of  an 
abnormal   brain,  but  in  the  reaction  of  the  normal  organism  to 
the  ordinary  physiological  effects  of  alcohol." 1 

533.  Now    very   obviously    the    foregoing    passage    contains 
numerous  very  grave,  if  unconscious,  misrepresentations  of  the  facts 
and  reasoning  which  led  to  the  belief  that  there  is  such  a  thing 
as  selection  by   alcohol  and   that   it   has  resulted   in   protective 
evolution.     Doubtless   the   alcoholic   diathesis,  the  susceptibility, 
has   often   been   regarded    as    a   symptom    of  a   diseased    mind. 
Indeed,    in    England    chronic    drunkenness    is    in    many    cases 
associated   with  mental   defect,2  possibly   because  feeble-minded 
persons   have   small   powers   of  restraint.3      But    no    reasonably 
well-informed  student  of  heredity  has  ever  held,  as  is  implied  in 
the  passage,  that  mental   defect  is   a  normal  accompaniment   of 
the  alcoholic  diathesis.     Were  the  latter  a  symptom  of  a  diseased 
mind  we  should  have  to  consider  all  primitive  humanity  and  half 
the  races  now  inhabiting  the  world,  including  the  whole  of  the 
aborigines   of  the   Western    Hemisphere,  as    mentally   diseased. 
Every  one  knows  men  and  women  of  great  intellectual  power  who 
drink  to  excess,  and  it  is  not  believable  that  North  Europeans 
are  on  the  average  more  defective  mentally  than  South  Europeans. 
Doubtless,    the   diathesis,    through   the   indulgence   it    tends    to 
provoke,  is  a  frequent  antecedent  of  disease,  but  by  itself  it  is  no 
more  a  disease  than  temerity  is  a  wound. 

534.  Again,  no  students  of  heredity  and  evolution,  not  even 
"less   responsible   students,"   have    assimilated    this  hypothetical 
drink-crave  to   a  peculiarity  of  anatomical   structure,  unless   by 
that    is    meant   the  belief,    common  to    all    psychologists,    that 
mental  facts  are  correlated  to  cerebral  facts.     If  the  "  potentiality 

1  Op.  cit.,  pp.  58-9- 

2  See  Branthwaite,  British  Journal  of  Inebriety,  Jan.  1908. 

3  See  §  699. 


INDUSTRIAL  DRINKING  317 

of  the  drunkard "  is  not  in  the  last  analysis "  a  simple  inborn 
trait,"  then,  in  the  name  of  clear  thinking,  what  is  it  ?  Even 
if  we  suppose  it  to  be  an  acquirement,  we  must  in  the  last  analysis, 
as  in  the  case  of  other  acquirements,  postulate  an  inborn  foundation 
for  it.  Whether  the  inborn  foundation  is  simple  or  compound  is 
irrelevant.  The  word  '  simple  '  has  not  to  my  knowledge  been  used 
by  any  adherent  of  the  theory.  Possibly  we  are  all  potential 
drunkards  in  the  sense  that,  under  very  exceptional  circumstances, 
we  are  all  capable  of  acquiring  a  liking  for  intoxication  ;  but  it 
is  beyond  doubt  that  some  of  us  are  so  constituted  that  we  become 
drunkards  more  readily  than  others.  This  liability  to  acquire 
a  liking  for  intoxication  is  the  diathesis,  the  inborn  trait,  the 
susceptibility.  If  the  writer  from  whom  we  quote  means  to  imply 
nothing  more  than  that  the  diathesis  is  not  the  only  factor  in  the 
causation  of  inebriety,  then  his  language  implies  also  that  some 
one  has  stated  that  it  is.  But,  in  point  of  fact,  no  one  has  been 
so  excessively  foolish.  The  influence  of  education,  fashion,  self- 
restraint,  accessibility  of  alcohol,  and  the  like  have  all  been  fully 
admitted.  For  example,  it  has  been  admitted  that  abstainers, 
who  will  not  drink,  and  Fuegians  who  cannot  procure  drink,  may 
have  the  diathesis  strongly  developed  and  yet  not  be  drunken. 
It  has  been  held  only  that  the  craving  for  drink  is  the  resul- 
tant not  of  one  factor,  but  of  two,  inborn  susceptibility  and 
previous  experience,  and  that  the  greater  the  susceptibility  the 
more  easily  does  the  experience  awaken  the  craving.  Yet  again, 
no  one  has  so  much  as  hinted  that  alcoholic  evolution  would 
lead  to  a  race  '  immune  to  drink  '  in  the  sense  implied.  Evolution 
is  never  perfect.  It  has  been  maintained  merely  that  evolution 
tends  so  to  decrease  the  susceptibility  of  a  race  exposed  to 
selection  that  it  becomes  increasingly  temperate,  even  in  the 
presence  of  increasing  supplies  of  alcohol. 

535.  During  the  Middle  Ages  the  belief  was  prevalent  that 
alcohol — presumably  in  moderation — was  beneficial  to  health 
and  strength.  Rightly  or  wrongly — wrongly,  I  think,  except  in 
certain  cases  of  depressed  health — this  belief  has  survived  to  the 
present  day,  particularly  amongst  medical  men  and  nursing 
mothers.  I  suppose,  however,  that  no  human  being  who  has 
an  average  experience  of  life,  and  is  not  a  real  lunatic,  believes 
that  alcohol  taken  in  excess  is  beneficial.  By  excess  I  mean  here 
an  amount  which  obviously  impairs  health  and  efficiency.  Certainly 
no  sane  excessive  drinker,  however  ignorant,  no  man  who  has 
experienced  the  resulting  temporary  paralysis,  indigestion,  loss  of 


3i8  THE  EVOLUTION  AGAINST  NARCOTICS 

appetite,   headache,    thirst,    'hot   coppers,'  nervousness,   delirium 
tremens,  and  the  rest,  is  under  any  such  delusion. 

536.  It  is  true,  of  course,  that,  if  a  soaker  of  the  lower  classes 
be  questioned,  he  may  lie,  and,  like  sots  of  a  higher  social  standing, 
may  excuse  himself  by  declaring  that   he  takes  alcohol   for  his 
health's  sake,  or  his  work's  sake,  or  his  stomach's  sake ;  but  the 
last   to   believe   him    will   be   his   own   mates,   who   perceive    in 
him  the  consequences  of  heavy  drinking.     To  ascertain  his  real 
sentiments  it  is  only  necessary  to  ask  his  opinion  of  some  other 
soaker — of  one  who  drinks  to  the  same  excess  as  himself.     Indeed, 
when  sick,  sorry,  and  repentant,  he  will  admit  his  fault,  and  swear 
an  amendment,  which,  as  a  rule,  temptation  subsequently  annuls. 
He  knows,  of  course,  that  "  a  hair  of  the  dog  that  bit  him  "  will 
temporarily  mitigate  the  unpleasant  feelings  aroused  by  previous 
drinking  ;  but  he  knows  also  that  the  only  permanent  cure  for 
his  miseries  is  abstinence  or  moderation.     In  many  cases,  lack  of 
money   will    afford    experience   of    the    advantages   of   sobriety. 
That  his  virtuous  assumption  of  drinking  for  his  work's  sake  is 
a  pure  fiction  is  proved  by  the  fact  that,  when  he  has  lost  his  job 
and  is  idle,  he  drinks,  if  he  can,  as  much  as  or  more  than  ever. 
Moreover,  for  thousands  of  years  laws  against  excessive  drinking 
have  been   common,  and    denunciation  of  it  an  everyday  affair. 
Almost  every  pulpit,  schoolroom,  and  reputable  newspaper  conducts 
a  campaign  against  it.     The  temperance  question  is,  and  has  long 
been  a  burning  one  with  the  public.     Our  workmen  have  a  collo- 
quialism, "  drinking  himself  to  death,"  which  is  commonly  applied 
to  chronic  soakers.      Slums,  workhouses,  prisons,  and  asylums  are 
full  of  the  victims  of  alcoholism.     Whenever  possible,  employers 
insist  on  sobriety.     In    every  workshop  and  factory  the  men  who 
abstain,  at  any  rate  during  working-hours,  are  known  to  achieve 
better  results  and  greater  prosperity  than  their  fuddled  comrades. 

537.  In  spite  of  all  this — by  way  of  proving  that  there  is  no 
such  thing  as  alcoholic  selection — we  are  now  assured  that  the 
British  workman  who  imbibes  to  excess,  drinks,  not  because  he 
enjoys  drinking,  but  merely  as  an  aid  to  labour.     "  This  is  the 
fundamental  factor."  x     It  is  supposed  that  he  is  poisoned  day  by 
day  and  ultimately  perishes,  not  because  he  is  tempted  by  pleasure, 
but  on  the  altar  of  duty;    whence  it   follows,   that   the  people 
eliminated  by  alcohol  are  not  those  who  are  especially  tempted  by 
it.     The  fact  that  every  race  is  temperate  precisely  in  proportion 
to  the  length  and  severity  of  its  past  experience  of  drink  is  quietly 

1  Alcoholism,  by  W.  C.  Sullivan,  M.D.,  pp.  115  ;  see  also  pp.  61,  114,  116. 


INDUSTRIAL  DRINKING  319 

ignored.  It  is  admitted  that  the  "  worker  who  does  his  labour  with 
the  help  of  alcohol  is  sure  to  have  recourse  to  the  drug  for  his 
ideals  of  pleasure,"  1  and  that  "  exceptions  to  this  rule  are  rare."  2 
In  other  words,  while  it  is  admitted  that  after  five  or  six  o'clock 
the  worker  drinks  for  the  sake  of  enjoyment,  it  is  assumed  that 
before  that  time  he  drinks  from  altruistic  motives.  With  the 
setting  of  the  sun  his  sensations  are  supposed  to  undergo  a 
radical  change.  We  are  told,  therefore,  that,  to  wean  workmen  from 
excessive  drinking,  nothing  more  is  necessary  than  to  convince 
them  that  the  habit  is  injurious  to  health  and  work.  Thereupon 
industrial  drinking,  the  only  harmful  form  of  indulgence,  will  cease.3 
538.  The  unconscious  humour  of  this  surprising  hypothesis  is 

1  Op.  cit.,  p.  62.  z  Op.  cit.,  p.  87. 

3  The  hypothesis  under  discussion  is  interesting  as  a  type  of,  and  is  really  not 
much  more  absurd  than  a  great  deal  that  has  been  written  on  the  problem  of, 
alcoholism  since  the  theory  of  alcoholic  evolution  was  formulated.  For  example, 
if  we  seek  to  demonstrate  the  existence  of  alcoholic  selection  and  its  corollary 
evolution,  plenty  of  people  will  at  once  inform  an  astonished  public  that  universal 
intoxication  is  advocated  as  a  cure  for  national  drunkenness.  If  we  protest  that 
we  advocate  no  such  thing  and  that  we  would  object  to  it  as  strongly  as  to 
universal  disease,  the  reply  is  that  it  follows  logically  from  our  opinions.  It  is 
quite  useless  to  indicate  to  intelligences  of  this  order  that  their  logical  conclusions 
are  not  necessarily  ours,  especially  when  we  have  strongly  and  categorically 
repudiated  them ;  that  unpleasant  truths  are  not  the  less  true  for  being  unpleasant, 
and  that  the  only  rational  way  of  refuting  opinions  they  dislike  is  not  to  make 
mis-statements  but  to  break  the  actual  chain  of  alleged  facts  and  the  inferences 
drawn  from  them.  It  may  be  thought  that  I  am  unfair  in  saying  that  the  drunken 
British  workman  is  described  as  sacrificing  himself  on  the  altar  of  duty.  But 
clearly,  if  drinking  makes  a  man  feel  better,  if  it  creates  in  him  a  "  sense  of  well- 
being,"  if  his  dislike  of  labour  is  lessened  thereby,  he  is  susceptible  to  its  charm. 
The  hypothesis  that  men  who  vary  in  all  known  characters  do  not  vary  in  this  one 
particular  of  receiving  pleasure  from  alcoholic  indulgence  is  too  grotesque  for 
serious  discussion.  It  has  been  trumped  up  by  people  unfamiliar  with  the  facts 
of  biology  to  meet  the  exigencies  of  the  moment.  Therefore,  if  it  be  said  that 
men  drink  because  of  the  sense  of  well-being  which  the  act  creates  in  them,  then, 
since  it  is  admitted  that  alcohol  is  a  considerable  cause  of  ill-health,  incapacity, 
and  death,  that  poison  must  tend  to  eliminate  especially  people  who  are  most 
susceptible  to  its  charm.  It  follows  that  the  hypothesis  under  discussion,  which 
is  supposed  by  its  supporters  to  controvert  the  theory  of  alcoholic  selection,  can 
do  so  only  when  it  premises  that  men  at  work  drink  alcohol,  not  because  they 
like  it,  not  because  it  creates  a  sense  of  well-being,  but  from  some  other  cause. 
The  cause  alleged  is  a  superstition,  said  to  be  derived  from  the  Middle  Ages  and 
still  prevalent  amongst  workmen,  that  an  amount  of  drinking,  which  anyone  not 
a  lunatic  would  know  to  be  injurious,  is  an  aid  to  labour.  Apart  from  its  amazing 
inferences,  the  volume  from  which  I  have  quoted  is  an  excellent  work.  It  is 
well  and  clearly  written,  contains  a  mass  of  useful  statistics,  and  proves — if  proof 
be  needed — quite  conclusively  that,  other  things  equal,  men  drink  most  when 
their  opportunities  are  greatest,  and  that  the  man  who  drinks  to  excess  all  day 
long  suffers,  as  a  rule,  more  than  the  man  who  drinks  only  in  the  evening. 


320  THE  EVOLUTION  AGAINST  NARCOTICS 

greatly  enhanced  when  we  read  the  facts  and  inferences  on  which 
it  is  founded.  "  The  petition  of  the  Middlesex  magistrates,  for 
example,  in  support  of  the  Gin  Act  of  1736  especially  singles  out 
journeymen  and  apprentices  as  the  classes  particularly  addicted  to 
this  sort  of  excess  " l  (i.e.  industrial  drinking).  Surely  it  is  suffi- 
ciently clear  that  the  action  of  the  magistrates  indicated  a  know- 
ledge that  excessive  drinking  in  work  time  is  injurious,  and  that  the 
drinking  of  the  journeymen  and  apprentices  was  excessive.  The 
notion  that  industrial  drinking  is  a  comparatively  modern  in- 
stitution is  absolutely  erroneous.  In  many  parts  of  Europe,  for 
thousands  of  years,  water  has  only  exceptionally  been  used  as  a 
beverage.  Even  as  regards  our  own  country,  it  may  be  laid  down 
as  a  general  rule  that,  before  the  introduction  of  tea  and  coffee, 
men,  whenever  able,  used  alcohol  at  all  times  of  the  day,  both  when 
working  and  playing.  Beer  and  cider  were  common  industrial 
drinks  with  our  ancestors,  especially  with  agricultural  labourers,  who 
were  the  great  majority  of  the  nation,  and  to  whom  it  was  customary 
to  make  a  regular  allowance.  The  condition  of  affairs  now  pre- 
valent in  Russia,  as  depicted  in  the  following  extract,  formerly 
obtained  in  England. 

539.  "  Feodor  asked  me  if  I  would  like  to  go  to  the  haymaking 
next  day.   .  .  .  '  Is  Feodor  at  home?'   I    asked.     Then   a   man 
appeared  from  a  neighbouring  cottage  and  said,  '  Feodor  is  in  the 
inn — drunk.'     '  Is  he  going  to  the  haymaking  ?  '    I  asked.     c  Of 
course  he  is  going.'     '  Is  he  very  drunk  ? '  I  asked.     *  No,  not  very  ; 
I  will  tell  him  you  are  here.'     Then  a  third  person  appeared,  a 
young  peasant  in  his   Sunday  clothes,  and  asked  where  I  was 
going.     I  said  I  was  going  to  make  hay.     '  Do  you  know  how  to  ? ' 
he  asked.     I  said  I  didn't.     *  I  see,'  he  said,  '  you  are  just  going  to 
amuse  yourself.     I  advise  you  not  to  go.     They  will  be  drunk,  and 
there  might  be  unpleasantness.'  .  .  .  Then  the  haymaking  began. 
The  first  step  that  was  taken  was  for  vodka  bottles  to  be  produced, 
and  for  every  one  to  drink  vodka  out  of  a  cup.     Then  was  a  great 
deal  of  shouting  and  an  immense  amount  of  abuse.     '  It  doesn't 
mean  anything,'  said  Feodor.     *  We  curse  each  other  and  make  it 
up  afterwards.'     Then  they  drew  lots  for  the  particular  strip  they 
should  mow;  each  man  carried  his  scythe  high  on  his  shoulder. 
((  Don't  come  too  near,'  said  Feodor ;  '  when  the  men  have  taken 
drink  they  are  careless  with  the  scythes.')  "  2 

540.  The  following  are  descriptions  of  devoted  workmen  who 

1  Qp.  dt.,  p.  ii. 

2  Maurice  Baring,  A  Year  in  Russia,  pp.  291-3.  London  :  Methuen  &  Co.,  1907. 


INDUSTRIAL  DRINKING  321 

are  supposed  to  believe  that  really  tremendous  drinking  bene- 
ficially affects  their  working  powers  :  "  We  may  take  as  a  type  for 
our  description  the  originally  healthy  workman  who  is  engaged  in 
a  trade  that  encourages,  or  at  least  allows,  the  habit  of  regular 
drinking  throughout  the  working  day,  and  who  probably  goes  in 
also  for  an  occasional  convivial  bout  at  the  week-end  or  on  special 
festivals.  After  a  period,  longer  or  shorter  according  to  the 
intensity  of  his  excesses,  such  a  drinker  will  begin  to  show  signs 
of  more  or  less  persistent  disorder,  usually  in  the  digestive  and 
nervous  functions;  he  will  be  aware  of  a  diminished  and  more 
capricious  appetite ;  he  will  suffer  from  pain  and  oppression 
referred  to  the  region  of  the  heart ;  he  will  often  have  nausea  or 
vomiting  on  awaking  in  the  morning ;  his  sleep  will  be  disturbed 
by  disagreeable  dreams,  by  attacks  of  muscular  cramp,  by  electric 
starts  in  the  limbs  ;  more  or  less  tremor  in  the  hands  and  feet, 
and  in  the  tongue  and  muscles  of  the  face,  will  be  evident  early  in 
the  day. 

541.  "As  the  intoxication   continues,  and  by  its  own  effects 
supplies  the  motive  for   increasing  excess,   all   these   symptoms 
become  aggravated  ;  the  morning  sickness  is  regular,  and  is  often 
accompanied  by  the  vomiting  of  blood  ;  the  tremor  is  constant ; 
nightmares  and  insomnia  divide  the  hours  of  rest,  and  foreshadow 
characters   which   will   appear   later   in   the  full  development  of 
delirium  tremens." 1 

542.  "  As  can  readily  be  imagined  from  the  amount   of  the 
docker's  average  wages,  the  non-alcoholic  part  of  his  dietary  is  apt, 
under  any  circumstances,  to  be  deficient,  and  the  money  which  he 
spends  on  liquor  leads  necessarily   to  a  further  lowering   of  his 
ordinary  food  allowance.     Not  only  does  his  dinner  money  very 
frequently  go  on  beer  before  the  meal  time  arrives,  but  even  when 
he  brings  his  dinner  with  him  from  home  he  will  often  sell  it  for 
a  few  pints  to  some  more  temperate  comrade.     This  condition  of 
under-feeding  contributes,  of  course,  to  the  more  rapid  development 
of  the  lesions  of  chronic  alcoholism  ;  and  it  is  usual  for  industrial 
drinkers  at  this  work  to  suffer  from  gastric  catarrh  and   severe 
nervous  disorders  before  they  reach  the  age  of  forty."  2 

543.  "  The  industrial  drinking  habits  which  we  have  described 
in  the  ordinary  docker  class  reach  a  further  degree  of  development 
in  some  special  varieties  of  waterside  labour.     We  may  take  as  an 
instance  the  Thames  Street  fruit  porters.     Amongst  these  porters 
the  method  of  work  and  payment  is  this :    The  overseer  takes  on  a 

1  Op.  tit.,  pp.  49-50.  *  Op.  cit.t  p.  8 1. 

21 


322  THE  EVOLUTION  AGAINST  NARCOTICS 

limited  number  of  men,  each  man  paying  a  nominal  deposit  for  his 
knot ;  the  porter  then  starts  work,  receiving-  at  the  warehouse  door 
for  each  box  he  takes  in  a  brass  ticket  marked  with  the  amount  of 
his  fee,  id.,  2d.  or  3d.,  according  to  the  size  of  the  box.  These 
tickets  he  can  get  changed  for  money  later  in  the  day  by  the  clerk, 
or  he  can  bring  them  at  any  time  to  a  public-house  which  enjoys 
the  special  privilege  of  cashing  them,  the  porter  taking  a  certain  pro- 
portion of  their  value  in  drink.  The  second  alternative  is,  of  course, 
nearly  always  adopted,  and,as  a  consequence,  a  large  number  of  these 
men  do  their  work  almost  exclusively  on  beer.  As  soon  as  its  effect 
is  sufficiently  visible  to  suggest  risk  of  accident,  the  man  has  to  give 
up  his  knot  for  the  day,  and  is  replaced  by  a  fresh  hand.  These 
conditions  produce  the  maximum  development  of  industrial 
alcoholism."  * 

5/1/1-  The  belief  that  parental  drinking  commonly  tends  to  alter 
the  germ-plasm,  and  so  results  in  filial  degeneration,  was  universal 
until  recently,  and  is  still  very  prevalent  amongst  medical  men. 
As  in  the  case  of  diseases  it  is  founded  mainly  on  '  common  sense/ 
and  on  statistics  which  indicate  that  the  progenitors  of  physical 
and  mental  *  degenerates '  have  often  been  intemperate.  Every 
reason  which  is  valid  against  microbic  disease  as  a  cause  of 
degeneracy  is  valid  against  alcohol.  It  is  not  to  be  denied,  of 
course,  that  parental  drinking  may  sometimes  (when  the  germ- 
plasm  has  varied  unfavourably  in  such  a  way  that  it  has  lost  its  power 
of  resistance)  be  a  cause  of  filial  degeneracy,  but  in  view  of  the 
fact  that  races  which  are  now  temperate  are  not  degenerate,  but 
were  originally  drunken,  it  is  impossible  that  it  can  be  a  common 
cause.  It  must  be  remembered  that  in  the  case  of  many  races 
alcohol  like  malaria  affects  practically  every  individual.  We  have 
all  known  people,  derived  from  drunken  stocks,  who  were  physically 
and  mentally  fit  and  capable — that  is,  people  whose  germ-plasm 
was  resistant  to  the  direct  action  of  alcohol.  It  follows  that,  even 
if  alcohol  does  tend  commonly  to  alter  the  germ-plasm,  especially 
on  its  first  introduction  to  a  race,  the  constant  elimination  of 
susceptible  strains  and  survival  of  resistant  types  would  infallibly 
tend  to  establish  a  high  degree  of  insusceptibility. 

545.  To  sum  up — the  questions  the  reader  must  decide  when 
studying  alcoholism  from  the  point  of  view  of  heredity  and  evolu- 
tion are[(i)  What,  fundamentally,  are  the  motives  which  induce 
men  to  become  intemperate  ?  Do  they  drink  to  excess  because 
they  enjoy  the  sensations  thus  awakened,  or  from  some  other  motive, 

1  Op.  dt.t  pp,  83-4. 


THE  CHIEF  PROBLEMS  OF  HEREDITY  323 

such  as  a  sense  of  duty  ?  (2)  Do  men  differ  in  their  '  by  nature ' 
susceptibility  to  the  charm  of  alcohol  ?  (3)  Is  alcohol  a  lethal  agent ; 
and,  if  so,  is  it  selective  ?  (4)  Bearing  in  mind  the  universal  truth 
that  races  are  temperate  when  exposed  to  alcohol  in  proportion  to 
their  past  experience  of  it,  but  show  no  other  change  that  can  be 
traced  to  it,  is  alcohol  a  cause  of  protective  evolution  or  of  degenera- 
tion? The  very  obvious  truths  that  men  of  the  same  race  drink, 
as  a  general  rule,  more  when  their  opportunities  for  drinking  are 
greater,  and  that  the  amounts  they  drink  depend  to  some  extent 
ou  their  previous  moral  training,  are  not  in  dispute. 

546.  Two  problems  of  heredity  are  of  outstanding  importance. 
The  first  is  the  problem  of  the  causation  of  variations.  The  second 
is  the  problem  of  the  proportion  which  the  '  innate '  characters  of 
any  species  bears  to  its  '  acquirements.'  In  the  section  of  this 
work  just  concluded  we  have  considered,  by  the  light  of  the  evidence 
furnished  by  microbic  diseases  and  narcotics,  the  problem  of  the 
causation  of  variations,  and  have  concluded  that,  when  we  take  all 
the  evidence  into  account,  it  is  inconceivable  that  the  great  mass 
of  variations  can  be  other  than  spontaneous.  In  the  next  section 
we  shall  consider  the  second  problem.  For  this  the  study  of  mind 
affords  peculiar  facilities. 


CHAPTER   XVII 
IDEALISM   AND   COMMON   SENSE1 

Mental  adaptation — Objections  to  the  hypothesis  that  minds  are  products 
of  evolution — Memory — Sense-impressions — What  a  sheet  of  paper  means — 
We  are  directly  aware  of  nothing  but  a  stream  of  feelings — The  mental  differences 
between  the  higher  and  the  lower  animals — How  we  construct  external  objects — 
The  differences  between  feelings  ordinarily  recognized  as  such,  and  those  which 
are  thought  of  as  properties  of  external  objects — Idealism  and  common  sense — 
Coherent  thought  and  common  sense — Except  at  rare  intervals  all  men  think  in 
terms  of  common  sense — There  are  no  thorough-going  idealists — The  two  views 
are  quite  incompatible — Invariable  succession  and  necessary  succession. 

547.  f  |  ^HE  bodies  of  the  higher  animals  are  compounded  of 

*  characters/   which,   in    turn,    are    compounded    of 

smaller  characters.     With  the  possible  exception  of 

a  few  traits  (by-products  of  evolution)  correlated  to  more  useful 

traits,  the  larger  and  older  characters — hands,  limbs,  hair,  nails, 

and  the  like — are  almost  all  adaptations ;  or,  if  vestigial  remains, 

have  been  adaptations.     The  smaller  and  newer  characters,  the 

1  Many  of  the  words  used  in  the  following  discussion  (chapters  xvii.,  xviii. 
and  xix.)  have  gathered  special  meanings  during  the  course  of  controversy. 
By  matter  I  mean  something  which  is  not  mind,  but  which  exists  external  to  mind, 
and  has  properties  that  excite  sensations  in  it,  and  is  thus  mediately  known  to  it. 
By  feeling  I  mean  not  merely  sensation,  but  any  state  of  consciousness.  By 
mind  I  mean  the  stream  of  feelings.  By  idealism  I  mean  the  philosophy  which 
supposes  that  "  the  sensations,  which,  in  common  parlance,  we  are  said  to  receive 
from  objects,  are  not  only  all  we  can  possibly  know  of  the  objects,  but  are  all  that 
we  have  any  ground  for  believing  to  exist,"  and  which  declares  "  we  have  no 
evidence  of  anything  which,  not  being  itself  a  sensation,  is  a  substratum  or 
hidden  cause  of  sensations,"  and  that  "  such  a  substratum  is  a  purely  mental 
creation  to  which  we  have  no  reason  to  think  that  there  is  any  corresponding 
reality  exterior  to  our  minds  "  (J.  S.  Mill,  Examination  of  Sir  William  Hamilton's 
Philosophy,  3rd  ed.).  By  common  sense  I  mean  merely  the  notion,  held  con- 
sciously or  unconsciously  by  every  one  during  ordinary  thought,  that  our  minds 
tell  us  of  a  universe  of  real  or  material  things  external  to  the  minds.  I  do  not  use 
the  word  as  implying  immediate  or  intuitive  cognition  of  real  things.  I  have 
thought  the  discussion  necessary,  partly  because  I  wish,  as  far  as  possible,  to 
establish  the  nature  of  the  relation  between  mind  and  body,  and  partly  (since  it  is 
sometimes  said  that  science  explains  nothing,  and  that  there  is  no  such  thing  as 
necessary  truth)  because  I  wish  to  define  what  appears  to  me  to  be  the  scope  of 
science,  and  the  significance  of  certain  terms  that  I  use,  such  as  cause,  invariable 
succession,  necessary  succession,  necessary  truth,  explain,  and  understand. 

324 


MENTAL  ADAPTATION  325 

variations,  are  not  necessarily  adaptations,  but  they  are  the 
materials  out  of  which  nature  manufactures  adaptations.  The 
constant  occurrence  of  them  is  an  adaptation.  Similarly,  the 
minds  of  animals  are  compounded  of  characters — sense-impres- 
sions, emotions,  memory,  and  the  like.  Doubtless,  individuals  and 
races  differ,  on  the  average,  as  much  in  mind  as  in  body ;  yet,  here 
again,  the  older  and  the  more  important,  the  specific  or  varietal 
characters,  the  '  faculties,'  are  all  or  almost  all  adaptations.  We 
can  think  of  no  animal  that  affords  evidence  of  possessing  mind, 
but  we  find  that  it  is  as  certainly  adapted  mentally  as  physically 
to  its  environment.  For  example,  human  sense-impressions, 
emotions,  instincts,  and  memory  all  fulfil  this  function.  Therefore, 
when  studying  mind  as  when  studying  body,  we  must  ever  keep 
this  great  truth  of  adaptation  before  us.  The  facts  are  such,  that 
if  our  hypotheses,  our  interpretations  of  the  facts,  do  not  accord 
with  it,  they  are  certainly  erroneous.1 

548.  We  saw  that,  when  the  whole  of  the  facts  are  taken  into 
account,  only  two  hypotheses  of  the  causation  of  physical  adaptation 
are  conceivable,  or  at  any  rate  have  been  conceived,  with  any 
degree  of  clearness — miracle,  and  natural  selection.  This  is  not  less 
true  of  mind.  We  are  bound  in  science  not  to  appeal  to  the 
supernatural  till  it  has  been  demonstrated  that  natural  explana- 
tions are  inadmissible.  Nevertheless,  some  writers,  even  amongst 
those  who  believe  that  the  human  body  has  evolved  under  the 
action  of  Natural  Selection,  have  been  inclined  to  attribute  to 
mind  a  supernatural  origin.  On  the  one  hand,  they  have  insisted 
that  mind  is  so  unique  that  it  can  have  been  evolved  out  of  nothing 
else  in  nature ;  on  the  other,  they  have  asked  how  it  is  possible 
that  such  human  *  faculties '  as  the  mathematical,  the  musical,  and 
the  devotional,  which,  seemingly,  have  never  contributed  to  the 
preservation  of  life,  can  have  been  brought  into  being  by  the 
action  of  Natural  Selection.  Mind  is  certainly  unique ,  neverthe- 
less, as  we  shall  see,  this  difficulty  is  not  absolutely  insurmount- 
able. At  any  rate,  it  is  not  a  unique  difficulty.  It  is  not  a  greater 
difficulty  than  many  others  which  science  first  ignores  and  then 
proceeds  as  if  they  had  been  surmounted,  leaving  the  consideration 
of  them  to  metaphysics,  which  seeks  to  be  more  thorough.2  The 
study  of  memory,  intellectually  the  most  important  of  all  the 
faculties,  has  been  constantly  neglected,  and  we  shall  find  that 
the  evolution  of  this  one  character,  easily  explainable  by  the 
theory  of  Natural  Selection,  furnishes  the  key  to  all  such  appa- 

1  See  §§  616  and  648.  *  See  §  590. 


326  IDEALISM  AND  COMMON  SENSE 

rently  unsolvable  riddles  as  that  of  the  existence  of  the  devotional 
and  mathematical  faculties. 

549.  The  moment  we  begin  to  discuss  mind  in  any  but  a  very 
superficial  way,  we  encounter  the  problem  of  the  connexion  be- 
tween mind  and  body.    Unless  I  start  by  dealing  with  this  problem, 
and  making  quite  clear  my  own  beliefs  and  the  reasons  why  I 
hold  them,  some  of  my  readers  will  presently  raise  hands  of  horror, 
and  declare  that  I  am  not  scientific,  but  metaphysical.     Probably 
some  of  them  will  do  so  in  any  case.    For  my  own  part,  I  propose, 
in  this  and  the  two  succeeding  chapters,  to  be  much  horrified  at 
the  metaphysical  attitudes  of  other  people.     In  the  end  I  think 
I   shall    be    in  a  position    to    insist   that,  if  I   am  metaphysical, 
I  am  so  only  to  an  extent  that  every  one  must  be  metaphysical. 

550.  I  am  writing  on  a  sheet  of  paper.     For  the  moment  I  am 
thinking  of  it,  in  the  '  common-sense '  way  usual  with  me  and  other 
people,  as  a  real  substantial  thing,  of  the  existence  of  which  I  am 
aware  through  my  senses.     My  sight  and  touch  tell  me  that  it  is 
oblong,  thin,  and  smooth.     My  sight  tells  me  that  it  is  white,  and 
marked  in  parallel  blue  lines.     Sight,  touch,  and  hearing  assure 
me  that  it  is  crisp.     Smell  informs  me  that  it  has  a  faint,  pleasant 
odour.     Taste  would  inform  me  that  it  has  a  flavour  which  is  not 
pleasant.     Muscular  sense  declares  that  it  has  weight.     Thus,  in 
ordinary  colloquialism,  the  sheet  has  '  caused '  certain  sensations 
in  me,  by  means  of  which  I  perceive  it,  by  means  of  which  I  gain 
a  perception  of  it.     Memory  supplements  this  information  ;  I  link 
up  the  sensations  I  have  just  received  with  other  information  which 
I  received  in  the  past,  and  with  thoughts  concerning  it.    I  recognize 
this  thing  which  now  lies  before  me  as  what  I  have  been  accustomed 
to  term  a  sheet  of  paper.     That  is,  I  form  a  conception  of  it  as  a 
sheet  of  paper. 

551.  But  to  go  deeper,  what  is  the  real  meaning  of  the  statement 
that  my  senses  and  thoughts  have  given  me  information  ?     Obvi- 
ously I  can  be  aware  of  nothing,  including  my  own  body  and  even 
my  mind,  except  through  sensations,  recollections,  and  thoughts, 
through  my  feelings.     They  are  the  only  conceivable  means  of 
communication  between  the  universe  and  that  inner  essential  me 
which  I  am  accustomed  to  regard  as  possessor  of  mind  and  body, 
and  the  observer  of  my  universe.1     Now,  still  using  the  language 

1  This  is  not  to  say  that  there  is  any  such  inner  essential  "  I."  There  may  be. 
I  do  not  know.  I  am  conscious  only  of  a  changing  stream  of  feelings  amongst 
which  are  feelings  by  means  of  which  I  contemplate  (recollect  or  foreshadow) 
other  feelings  which  are  past  or  which  may  arise.  I  say  only  that  in  my  everyday 
thinking  I  am  accustomed,  more  or  less  unconsciously,  to  postulate  this  being. 


MENTAL  SYMBOLISM  327 

of  common  sense,  of  everyday  life,  consider  the  sense  of  sight. 
We  are  told  that  I  see  the  paper  because  light,  which  is  some  sort 
of  vibration  in  the  ether  that  surrounds  us,  passes  from  a  luminous 
object  (e.g.  the  sun)  to  the  paper,  where  some  of  it  is  absorbed,  and 
whence  the  remainder  is  reflected  to  the  retina  of  my  eye,  where 
it  sets  up  chemical  changes.  These  chemical  changes  set  up  other 
chemical  or  molecular  changes  in  my  optic  nerve.  These,  yet 
again,  set  up  other  similar  changes  in  my  brain.  Thereupon 
there  dawns  within  that  dark  box,  my  skull,  a  feeling  which  I 
call  a  sight  of  the  paper.  In  an  analogous  way  my  other 
senses  convey  their  items  of  information.  Now,  plainly,  feeling, 
which  has  neither  extension,  nor  colour,  nor  weight,  nor  any 
other  of  the  properties  which  I  am  accustomed  to  ascribe  to 
material  things,  cannot  in  the  remotest  degree  resemble  the 
chemical  changes  in  my  brain,  optic  nerve,  or  retina,  or  the 
vibrations  of  the  ether  that  lies  between  the  retina  and  the  paper. 
Nor  can  it,  an  immaterial  thing,  resemble  the  material  thing,  the 
paper.  It  can,  at  best,  be  only  a  sign  and  a  symbol  to  me  of  the 
real  thing,  the  paper. 

552.  I  find  that  some  of  my  feelings  are  so  unlike  that  I  can 
institute  no  comparison  between  them.     Thus  the  '  crisp  '  sensation 
of  touch  which  I  get  when  I  indent  the  paper  is  quite  unlike  the  crisp 
look  of  it,  or  the  crisp  crackle  I  hear.    I  use  the  same  word  in  each 
instance,  but   the  several  sensations  it  describes  are  not  at   all 
similar.     I  may  say,  indeed,  that  all  these  sensations  are  faint  or 
vivid,  but  then  I  indicate  no  essential  likeness  except  the  degree 
in  which  they  impress  me.     If  feelings  may  be  incomparable,  how 
much  more  incomparable  must  be  feelings  and  material  things? 
Besides,  how  can  light,  undulations  in  the  ether,  passing  between 
the  sheet  of  paper  and  my  eye,  convey  anything  at  all  like  a  real 
sheet    to  my  retina  ?      How   can  the   series   of  changes   in   my 
optic  nerve   convey  anything   of  the   sort  to   the   brain  ?     How 
can  the  series  of  changes  in  the  latter  create  or   accompany  a 
feeling  which  is  remotely  like  the  paper  ? 

553.  I  write  the  word  'paper,'  and  it  stands  to  me  for  a  sign 
and  a  symbol  of  the  sound,  the  spoken  word  '  paper,'  which  it  is 
incomparably  unlike.     Similarly,  the  spoken  word  is  only  a  symbol 
of  the  seen,  felt,  heard,  tasted,  smelt,  or  weighed  thing,  '  paper.' 
So  also,  in  a  sense  even  more  thorough,  my  several  feelings  of  paper 
are  only  signs  and  symbols  of  the  *  real '  thing,  which,  as  I  suppose, 
awakens  them.     That  real  thing  is  altogether  outside  the  circle  of 
my  consciousness,  within  which  are  nothing  but  feelings.     By  no 


328  IDEALISM  AND  COMMON  SENSE 

manner  of  means  can  I   gather  anything  more  than  a  symbolic 
knowledge  of  it. 

554.  Indeed,  to  go  yet  deeper,  it  is  a  question  whether  I  can 
gather  even  a  symbolic   knowledge.     I    have   surmised  that   my 
feelings  have  been  awakened  by  a  real  object,  but  it  is  impossible 
to  test  that  hypothesis.   The  symbolism  of  my  dreams,  if  symbolism 
it  be,  is,  I  am  accustomed  to  believe,  very  misleading.     How  can  I 
know  whether  the  symbolism  of  my  waking  hours  is  of  a  more 
truthful  kind  ?     My  waking  feelings  seem  to  link  together  better 
than  my  dream  feelings,  but  the  fact  that  they  link  better  together 
does  not  prove  that  they  are  symbols  of  anything.     At  any  rate 
this  is  certain,  that  what  I  term  the  '  properties '  of  the  material 
object,  extension,  weight,  colour,  and  the  like,  are  really  feelings 
in  me.     Strip  the  material  object  of  these  properties,  of  these  my 
private   feelings,   and    what   remains   of  it  ?      The   remainder,  if 
remainder  there  be,  the  '  matter  in  itself,'  the  nomnenon,  is  quite 
inconceivable.     For  me  it  has  no  thinkable  existence.     I  close  my 
eyes,  and  have  a  recollection  of  the  sheet.     That  recollection  is 
not  more  a  mental  and  less  a  material  thing  than  the  perception 
I  had  when  my  eyes  were  open. 

555.  It  is  evident  that  the  only  existence  of  which  we  are  really 
aware  is  a  stream  of  feelings.     That  stream  of  feelings  is  the  whole 
of  consciousness.     For  us  the  universe  is  a  universe  of  appearances, 
of  phenomena,  which  we  construct  out  of  our  own  feelings.     Time 
and  space  are  only  modes  of  thought,  the  former  being  concerned 
mainly  with  appearances  that  occur  in  succession,  the  latter  with 
appearances  which  co-exist.     We  speak  of  mind  and  matter,  but 
from  first  to  last  we  know  of  nothing  but  mind.     We  are  conscious 
of  nothing  else.     Matter  is  a  metaphysical  abstraction,  an  unknown 
and  unknowable  something  which  has  been  surmised  by  common 
sense,  but  only  surmised,  to  be  in  some  way  the  cause  of  phenomena. 
But  our  minds  are  so  constructed  that  we  are  impelled  to  attribute 
material  existence  to  many  appearances.     Thus  this  sheet  of  paper 
appears  to  me  a  thoroughly  material  object.     If  I  tear,  or  burn, 
or  crumple  it,  I  seem  to  be  wrecking  a  material  thing  with  material 
hands.     It  is  only  when  I  pursue  a  very  unusual  line  of  thought  that 
I  am  able  to  realize  that  I  am  dealing  throughout  with  groups  of  feel- 
ings which  experience  tells  me  tend  to  follow  one  another  in  certain 
sequences.     The  sight  of  the  paper,  the  intention  to  tear  it,  the 
sight,  and  sound,  and  tactile  sensations  of  tearing,  and  the  feeling 
of  an  intention  accomplished  are  all  equally  mental  phenomena. 

556.  We  shall  see  later  that  it  is  probable  that  animals  low  in 


THE  CIRCLE  OF  CONSCIOUSNESS  329 

the  scale  of  life,  for  example  most  insects,  intuitively  regard  the 
objects  revealed  to  them  by  their  senses  as  real  existences.  On 
the  other  hand,  it  is  likely  that  the  human  mind  begins  as  a  chaos 
of  feelings,  some  of  which,  by  a  process  of  gradual  and  unconscious 
inference,  are  ultimately  referred  to  external  bodies  as  properties 
or  qualities  of  them.  In  other  words,  the  insect  has  an  intuitive 
belief  in  the  existence  of  the  universe  which  his  mind  constructs, 
while  the  human  being  slowly  builds  up  a  similar  belief.1  The 
latter  then  divides  his  feelings  into  classes,  one  of  which  is  regarded 
as  a  collection  of  mental  happenings,  and  the  other  as  a  collection 
of  external  objects.  Thus  the  pain  caused  by  a  cut  from  a  knife 
is  regarded  as  a  feeling,  whereas  the  colour,  extension  and  weight 
'of  the  knife'  are  supposed  to  be  properties  of  a  material  object. 
Ultimately  the  human  being  finds  it  extremely  difficult  to  think  and 
speak  of  his  '  physical '  universe  as  other  than  a  collection  of  external 
objects.  Both  thought  and  language  become  moulded  on  that  belief. 
Thus  I,  while  insisting  that  material  objects  are  unknown  to  us,  have 
just  used  words  which  imply  an  unquestioning  faith  that  insects, 
human  beings,  and  knives  are  realities  external  to  me.  I  have  also 
used  the  words  '  we '  and  '  us,'  and  have  written  this  book  on  the  as- 
sumption that  other  people  will  read.  But  other  people,  other  minds, 
are  just  as  much  unknown  to  me,  just  as  much  outside  the  circle  of  my 
consciousness  as  sheets  of  paper.  Indeed,  other  minds  are,  if  any- 
thing, more  outside  the  circle  of  my  consciousness  than  material 
bodies;  for  I  can  only  arrive  at  the  notion  of  these  other  minds  by 
observing  that  bodies  move  in  such  a  way  (talk,  gesticulate,  etc.) 
that  they  seem  to  be,  like  my  own  body,  under  mental  vcontrol. 

557.  And  now  I  wish  to  fix  the  reader's  attention  on  a  matter 
which  is  of  very  great  importance,  but  which  is  never  accorded  due 
weight.  He  must  bear  with  me  if  I  use  such  words  as  '  reader,' 
'nurse,'  'wall,'  and  the  like,  and  so  constantly  express  myself  in 
common-sense  terms.  Language  affords  no  other  way  of  indicat- 
ing my  meaning.  If  I  had  always  been  an  idealist,  if  from  the 
beginning  I  had  ever  regarded  my  feelings  merely  as  feelings,  if  I  had 
never  draped  them  about  supposed  external  objects  as  properties  of  the 
latter,  if  1  had  never  put  a  materialist  construction  on  them,  I  should 
now  be  living  in  a  chaos  of  unmeaning  feelings.  We  do  not  know 
to  what  extent  a  newly  born  infant  has  an  intuitive  belief  in  an 

1  Of  course,  I  do  not  mean  that  the  human  infant  at  first  regards  all  his  feelings 
merely  as  feelings  and  afterwards  changes  his  opinion.  Like  the  insect  he  does 
not  think  about  it.  I  mean  merely  that  he  learns  to  do  that  which  the  insect  does 
intuitively. 


330  IDEALISM  AND  COMMON  SENSE 

external  world,  but  there  are  good  reasons  for  believing  that  his 
intuitions  cover  but  a  very  small  portion,  if  any  portion,  of  his  total 
mental  field.  He  is  emphatically  a  creature  who  learns.  When  I  was 
born,  a  flood  of  new,  and  strange,  and  doubtless  incomprehensible 
feelings  beat  upon  me.  Probably,  for  example,  the  walls  of  my  room 
were  not  conceived,  as  they  were  later  when  my  education  was  well 
advanced,  as  material  things  having  extension  and  other  properties  ; 
they  were  only  patches  of  light  and  shade,  and  were  not  even  thought 
of  as  such.  The  nurse  consisted  only  in  similar  patches.  Her 
movements  resulted  in  changing  patches  which  were  not  dis- 
tinguished from  the  changes  caused  by  the  purposeless  movements 
of  my  own  eyes.  Probably  the  sounds  she  made  as  well  as  the 
feelings  that  came  from  my  skin  and  other  organs  were  not 
differentiated,  were  not  understood,  in  any  way. 

558.  But  gradually  my  wonderful  faculty  of  memory  did  its 
work.     By  means  of  it  I  stored  impressions  in  my  mind,  and  learned 
with  ever-increasing  power  to  link  them  together.1     And  this  link- 
ing  was   performed,    not    merely   by   recording    likenesses    and 
differences,  coexistences  and  sequences,  but  also  by  processes  of 
inference  which  were  none  the  less  real  because  at  first  rudimentary, 
and  of  only  gradual  growth  in  scope  and  accuracy.     In  this  way 
groups  of  feelings  gained  coherence,  and  linked  themselves  to  other 
groups.      Thus,   at   length,    I    gathered   the   notion   that   certain 
patches  of  light  and  shade  proceeded  from  a  permanent  material 
wall   were   properties  of  the  wall.      Thereupon    all    the  feelings 
successively  excited  by  the  wall  began  to  fall  into  their  places,  like 
pieces  in  a  well-designed  mosaic.     Though  the  patches  changed 
when  my  position  was  changed,  or  when  there  was  more  or  less 
light,  or  when  the  direction  of  the  light  was  changed,  or  when  the 
nurse  moved  about,  yet  I  began  to  connect  all  such  changes  not 
with  changes  in  the  wall,  but  with  changes  in  my  position,  and  so 
forth.     Another  vast  group  of  feelings  linked  themselves  together 
in  the  notion  of  a  material  nurse,  and  cohered  notwithstanding  even 
greater  changes  in  her.     An  even  vaster  group  were  gathered  in 
the  notion  of  a  body,  consisting  of  head,  trunk,  and  limbs,  which 
I  came  to  regard  as  peculiarly  mine,  which  was  I,  and  from  which 
I  derived  some  feelings  (e.g.  '  physical '  pain  and  pleasure)  that  were 
unlike  those  excited  by  all  other  bodies. 

559.  Here  then  is  the  point  I  wish  to  emphasize — the  truth  that 
/  have  been   able   to   classify  by  feelings,  and  become  a   rational 
being)  only   because  from   early  infancy   I  have   referred  them  to 

1  See  §  666. 


THE  CONSTRUCTION  OF  THE  UNIVERSE          331 

external  objects.  In  other  words  unless  groups  of  my  feelings  had 
draped  themselves  about  a  supposed  material  wall,  and  others  about 
a  supposed  material  nurse,  and  so  on,  they  would  not  have  cohered  at 
all.  It  was  the  hypothesis,  which  gradually  and  inevitably,  owing 
to  the  constitution  of  my  mind,  I  formed  of  the  existence  of  external 
objects  that  gave  them  meaning  and  order,  and,  therefore,  coherence. 
Otherwise  my  memory  could  no  more  have  held  them  together 
than  it  now  can  the  shifting  colours  of  a  kaleidoscope.  Though 
all  the  evidence  indicates  that  our  memories  are  particularly  re- 
tentive when  we  are  young,1  yet  I  can  remember  nothing  of  what 
happened  to  me  during  early  infancy.  It  is  hard  to  explain  this 
fact  except  by  the  hypothesis  that  my  world  was  then  for  me  a 
very  complex  kind  of  kaleidoscope  that  furnished  not  only 
sensations  of  sight,  but  multitudes  of  other  sensations  as  well,  which, 
because  they  were  then  incoherent,  could  not  be  remembered.  It  is, 
therefore,  the  coherence  of  my  sensations  about  supposed  external 
objects  that  has  rescued  me  from  chaos. 

560.  To  illustrate  by  an  example  how  my  {  material '  world  was 
created :  a  little  while  ago  I  linked  together  a  group  of  entirely 
dissimilar  feelings  (visual,  tactile,  etc.),  by  conceiving  them  as 
properties  of  a  sheet  frof  paper.  This  group  I  then  linked  with 
other  groups,  other  sheets  of  paper,  the  recollection  of  which  had 
dwelt  more  or  less  vaguely  in  memory,  and  by  thinking  about 
which  I  had  reached  the  general  conception  of  a  sheet  of  paper  as 
distinguished  from  perceptions  and  recollection  of  particular  sheets 
of  paper.  The  economy  of  thought  achieved  by  means  of  such 
general  conceptions  is  very  great;  thus  I  do  not  now  need  to 
remember  thousands  of  individual  sheets  of  paper,  but  only  a  con- 
ceptual one  which  is  my  notion  of  that  kind  of  object.  Now,  again, 
as  I  sit  thinking,  I  link  up  the  group  of  feelings  which  represents 
to  me  the  sheet  of  paper  with  another  group  which  represents  the 
table  on  which  it  is  lying.  The  compound  group  thus  constituted, 
forms  part  of  a  more  highly  compounded  group  which  represents 
the  room  in  which  I  am.  That,  yet  again,  is  linked  with  memories 
of  the  room,  with  memories  of  the  house  and  its  inmates,  the  street, 
the  town,  the  surrounding  country,  the  whole  of  my  world.  So 
the  universe  as  conceived  by  me  was  constructed.  Very  early  a 
division  was  made  between  feelings  which  were  recognized  as  feel- 
ings (e.g.  emotions  and  recollections)  and  groups  of  feelings  which 
were  supposed  to  be  material  objects  in  the  external  world.  Only 
long  after  manhood  was  reached  did  I  begin  to  suspect  that  I 

1  See  §  652. 


332  IDEALISM  AND  COMMON  SENSE 

have    never    been    really    aware    of  anything    but    my    private 
feelings. 

561.  Between  the  feelings  which  I  ordinarily  recognize  as  mere 
feelings  (recollections,  imaginings,  and  the  like),  and  those  which 
I   refer  to  external  objects  as  properties  of  them  or  as  caused 
directly  by  them  (i.e.  my  sense-impressions'),  there   exists  a  vast 
difference.     Thus,  what  I  suppose  to  be  the  sight  of  a  dog,  or  the 
pain  caused  by  his  bite,  is  immensely  more  vivid  than  my  thoughts 
about   such   an   event.      Moreover,    sense-impressions   follow  one 
another  in  an  infinitely  more  coherent  and  orderly  way  than  do 
thoughts.     Indeed,  so  orderly  is  the  procession  of  the  former  that 
we  feel  intense  surprise  when  the  usual  order  is  apparently  broken, 
and  we  immediately  cast  about  to  restore  it,  or,  in  other  words,  to 
discover  a  cause  for  the  break,  which  we  firmly  believe  to  be  only 
apparent.     Thus,  if  I  had  the  feeling  of  a  dog  biting  me  when  no 
dog  was  in  sight,  I  should  feel  unbounded  astonishment,  and  should 
immediately  form  all  sorts  of  hypotheses  to  account  for  the  event. 

562.  Doubtless,   it   is   this   peculiar  vividness,  and   above   all 
coherence  of  sense-impressions,  the  way  they  link  themselves  in 
related  groups,  which  cannot  be  altered  at  will  but  may  be  verified 
by  repeated  observation  even  after  a  length  of  time,  that  has  given 
rise  to  my  notion  of  external  objects  (included  amongst  which 
is  my  own  body) ;  whereas  the  lack  of  a  similar  coherence  and 
vividness  amongst  other  feelings  (e.g.  thoughts)  has  led  to   the 
unhesitating  recognition   of  them   as   mere   mental    phenomena. 
Thus,  all  the  impressions  which  I  gather  from  the  objects  in  this 
room   cohere  together  so  strongly  that  as  they  are  collectively 
to-day,  so,  very  nearly,  they  were  yesterday,  and  will  be  to-morrow. 
They  are  invariably  so  similar,  so  closely  repeated  in  the  same 
groups,  that  they  have  driven  me  to  think  they  represent  the  same 
external  objects — the  same  table,  the  same  chair,  the  same  walls, 
and  roof  and  floor.     If  I  wish  to  see  again  what  once  I  saw  on  the 
way   from    New   Zealand    I  can   do  so;    for,    if  the  journey  be 
repeated,  a  long  train  of  similar  sense-impressions  will  follow  one 
another  in  similar  array.     Forgotten  scenes,  appealing  to  awakened 
memory,  will  insist  as  strongly  as  anything  I  can  still  recall  on  a 
reality  independent  of  my  mind.     Even  when  I  read  a  description 
in  a  book,  I  am  able  to  verify  it  by  examining  the  place  or  object 
described.     But  in  my  thoughts  I  can  pass,  and  habitually  do  pass, 
in  a  moment  from  the  room  to  India  or  Honolulu,  or  Mars,  and 
in  two  consecutive  instants  can  be  concerned  in  a  dog-fight  round 
the  corner,  or  a  Saxon  coronation.     It  is  no  wonder,  then,  that  I 


MENTAL  COHERENCE  333 

have  been  led  to  refer  thoughts  to  a  mental  world,  and  sense-impres- 
sions to  external  objects  as  properties  of  them,  or  as  caused  directly 
by  them.  Indeed  the  coherence  and  vividness  of  my  sense-impres- 
sions is  my  only  ground  for  inferring  the  existence  of  a  reality 
which  is  beyond  them,  and  which,  as  I  suppose,  they  symbolize — 
for  I  do  not  think  they  can  do  more — to  my  mind.  So  coherent 
and  capable  of  being  tested  in  diverse  ways  is  the  story  told  by 
sense-impressions,  that  nothing  is  more  certainly  true  than  the  ex- 
istence of  the  reality  they  insist  on — except  that  which  is  very  much 
more  certain,  the  existence  of  the  sense-impressions  that  tell  the  story. 

563.  Evidently,  as  I  say,  my  feelings  have  gained  coherence 
and  meaning,  and  I  have  achieved  such  knowledge  and  skill  in 
thinking  as  I  possess  only  because  I  have  thought  in  the  common- 
sense  way  to  which  I  have  been  driven,  as  it  seems,  by  the  very 
constitution  of  my  mind.     Without  that  previous  common-sense 
thinking,  my  thoughts  would  now  be  infinitely  more  chaotic  than 
any  that  occur  in  my  dreams.     For,  at  least,  in  my  dreams  my 
feelings  do  not  constitute  a  meaningless  procession.    All  of  them  are 
grouped  or  linked  together  by  being  thought  of  as  properties  of,  or  as 
caused  directly  or  indirectly  by,  external  objects.    Even  now,  when 
for  an  hour  or  more  I  have  forced  myself  to  think  in  idealist  terms, 
and  have  decided  that  I  know  nothing  of  what  lies  beyond  my 
feelings,  yet,  so  strong  is  my  tendency  to  think  in  a  common-sense 
way,  that  my  wife  and  child  have  only  to  come  into  the  room,  and 
the  whole   philosophic   tangle   is   instantly   dissipated.     I    return 
forthwith  to  common  sense.     They  become  warm,  living  material 
realities.     Realities,  too,  become  the  room  and  all  within  it,  the 
house,  the  street,  the  whole  universe. 

564.  Now,  if  my  feelings  have  gained  coherence  only  because  I 
have  draped  groups  of  them  about  external  objects,  which  I  do  not 
know  to  be  other  than  illusions,  of  what  value  is  the  coherence  ? 
If  the  objects  are  illusions,  the  coherence  is  delusive.     How  am  I 
to  know  that  my  thinking  is  in  any  way  better  than  the  imaginings 
of  a  madman  (phenomenal  to  me),  who,  like  me,  depends  on  his 
feelings,  and  is  unlike  me  only  in  that  he  perceives  some  groups  or 
links  together  some  groups  differently?     It  would  be  absurd  to 
argue   that   my    mind    is    normal   and   his   abnormal.      For   the 
thoroughgoing  idealist  there  are  no  such  things  as  mental  nor- 
mality and  abnormality.     He  knows  no  more  of  other  minds  than 
of  material  bodies.     Indeed,  the  assumption  that  there  are  other 
minds,    normal    or    abnormal,    is    tantamount     to     a     complete 
abandonment  of  the  whole   idealist   position.     For  if  there  are 


334  IDEALISM  AND  COMMON  SENSE 

other  minds  that  have  perceptions  similar  to  those  which  occur  in 
my  mind,  there  is  no  reason  to  doubt  that  there  are  bodies,  that 
there  is  a  something,  a  reality,  external  to  those  minds,  which 
causes  the  similarity  of  feeling.  That  something  is  what  common 
sense,  which  postulates  other  minds,  designates  as  "  matter."  It 
follows,  that,  though  the  coherence  which  common  sense  has 
bestowed  on  my  feelings  is  (regarded  as  nothing  more  than 
coherence)  very  real,  and  though  it  lingers  when  I  think  as  an 
idealist,  yet,  beyond  the  satisfaction  it  affords  me,  it  has  no  value 
to  me  (as  an  idealist) ;  for,  as  far  as  I  know,  it  is  founded  on 
illusion.  Idealism,  then,  leads  to  a  cul-de-sac,  from  which  there  is 
no  escape ;  and  the  thoroughgoing  and  consistent  idealist  has  no 
right  to  proceed  beyond  a  wondering  and  bewildered  contemplation 
of  his  own  feelings. 

565.  But  there  are  no  thorough-going  and  consistent  idealists. 
There  never  have  been  any.  All  idealists  have  thought  more  or 
less  coherently,  and  have  failed  to  note  that,  if  common  sense  is 
based  on  illusion,  coherent  thinking  is  based  on  it  also.  Very 
certainly,  notwithstanding  ardent  effort,  /  am  no  consistent  idealist. 
I  find  that  I  constantly  act  under  an  intense  common-sense 
conviction  that  I  am  a  material  item  in  a  material  world,  which 
contains  many  similar  items.  As  it  is  with  me,  so  I  suppose  it  is 
with  these  other  items,  these  other  men.  Now  and  then,  though 
seldom,  a  rare  individual  may  think  for  a  little  space  in  futile 
idealistic  terms — terms  which,  as  we  see,  have  become  possible  to 
him  only  because  common  sense  has  previously  trained  his  thinking 
powers.  But  ever  his  mind  tends  to  swing  back  to  the  common 
sense  that  has  become  engrained  in  his  nature.  Therefore  he 
makes  provision  for  his  family,  and  performs  other  altruistic 
actions,  engages  in  politics,  distinguishes  between  immaterial 
minds  and  material  brains,  is  pleased  or  vexed  with  his  friends, 
speaks  to  other  people,  and  writes  books  for  them  to  read — even,  it 
may  be,  books  which  demonstrate  more  or  less  logically  and  con- 
clusively that  neither  they  nor  the  books  have  any  known  existence. 
As  Clifford,  who  declared,  "  I  do  believe  that  you  are  conscious  in 
the  same  way  as  I  am  ;  and  once  that  is  conceded,  the  whole 
idealist  theory  falls  to  pieces," x  but  who,  nevertheless,  wrote  and 
lectured  at  great  length  as  an  idealist,  said  very  properly,  "A  true 
idealism  does  not  want  to  be  stated,  and  conversely,  an  idealism 
that  requires  to  be  stated  must  have  something  wrong  about  it."2 

1  Lectures  and  Essays,  Letter  to  Sir  F.  Pollock,  p.  33. 

2  Lectures  and  Essays,  Philosophy  of  the  Pure  Sciences,  p.  209. 


OTHER  MINDS  335 

Formerly,  these  inconsistent  idealists,  while  tacitly  admitting  the 
existence  of  other  people,  denied  that  of  matter,  for  which 
"Berkeley  placed  God]  Kant  and  after  him  Schopenhauer  placed 
Will\  and  Clifford  placed  Mind-Stuff"^  Now,  to  crown  all,  Pro- 
fessor Karl  Pearson,  pinning  his  faith  to  Hume,  and  declaring  that 
he  knows  nothing  beyond  the  veil  of  his  sense-impressions,  is 
highly  contemptuous  of  the  opinions  of  these  metaphysicians — 
and  so  joins  their  company.  Even  Hume  wrote  for  other  minds.2 

1  Pearson,  Grammar  of  Science,  ed.  1900,  p.  68,  footnote. 

*  In  this  question  of  other  minds  lies  the  crux  of  the  whole  problem.  When 
I  declare  that  the  only  existence  known  to  me  is  the  stream  of  feelings  which 
constitutes  my  own  mind,  and  that  this  stream,  especially  when  I  divest  it  of  the 
coherence  conferred  by  common  sense,  does  not  furnish  evidence  of  the  existence 
of  anything  outside  of  it,  I  am  on  safe  ground.  But  when  I  suppose  that  there 
are  other  minds,  I  make  a  guess  which  I  cannot  test,  and  which  is  therefore  of  the 
same  nature  as  that  made  by  the  materialist.  Attempts  have  been  made  by 
idealists,  who  deny  or  doubt  the  existence  of  material  objects,  to  demonstrate 
the  existence  of  the  other  minds  to  which  they  appeal.  For  example,  J.  S. 
Mill  (Examination  of  Sir  William  Hamilton's  Philosophy,  3rd  ed.),  declares,  "  I  do 
not  believe  that  the  real  externality  to  us  of  anything,  except  other  minds,  is 
capable  of  proof "  (p.  239).  He  distinguishes  between  actual  sensations  and 
Permanent  Possibilities  of  Sensations.  The  latter  are  those  groups  of  sensations 
which  we  drape,  or  under  fitting  conditions  might  drape,  about  supposed  external 
objects ;  and  which,  so  grouped,  may  recur  again  and  again.  Calcutta  is  such  a 
Permanent  Possibility.  "  I  do  believe,"  says  Mill,  "  that  Calcutta  exists,  though 
I  do  not  perceive  it,  and  that  it  would  still  exist  if  every  percipient  inhabitant 
were  suddenly  to  leave  the  place,  or  be  struck  dead.  But  when  I  analyse  the 
belief,  all  I  find  in  it  is,  that  were  these  events  to  take  place,  the  Permanent  Possi- 
bility of  Sensation  which  I  call  Calcutta  would  still  remain  ;  that  if  I  were  suddenly 
transported  to  the  banks  of  the  Hoogly,  I  should  still  have  the  sensations,  which, 
if  now  present,  would  lead  me  to  affirm  that  Calcutta  exists  here  and  now.  We 
may  infer,  therefore,  that  both  philosophers  and  the  world  at  large,  when  they 
think  of  matter,  conceive  it  really  as  a  Permanent  Possibility  of  Sensation.  But 
the  majority  of  philosophers  fancy  that  it  is  something  more  ;  and  the  world  at 
large,  though  they  have  really,  as  I  conceive,  nothing  in  their  minds  but  a  Per- 
manent Possibility  of  Sensation,  would,  if  asked  the  question,  undoubtedly  agree 
with  the  philosophers  "  (p.  235).  In  spite,  then,  of  the  circumstance  that  these 
Permanent  Possibilities  may  exist  before  the  percipient  mind,  and  survive  after  it, 
Mill  rejects,  as  unprovable,  the  notion  that  they  are  caused  by  matter — by  that 
which  is  not  part  of  the  mind,  but  external  to  it,  and  which  possesses  properties 
that  excite  in  the  mind  sensations  which  symbolize  those  properties.  Neverthe- 
less, because  a  certain  Permanent  Possibility  (the  recurring  group  of  sensations 
which  he  calls  his  body)  is  constantly  associated  with  his  mind,  he  endows  this  part 
of  his  mind  with  all  his  mind  ;  at  any  rate,  because  other  of  his  Permanent  Possi- 
bilities (which  he  calls  the  bodies  of  other  people)  resemble  his  body,  he  supposes 
that  these  Possibilities  have  minds  of  their  own.  In  other  words,  he  supposes 
that  Possibilities  which  are  not  external  to  his  mind  have  themselves  minds  which 
are  external  to  it.  From  groups  of  his  sensations  he  thinks  he  can  legitimately 
infer  the  existence  of  other  minds  ;  but,  though  he  believes  that  other  minds  can 
have  identical  sensations  only  when  placed  under  identical  conditions  (e.g.  at 
Calcutta),  he  thinks  he  is  not  in  a  position  to  infer  the  existence  of  an  external 


336  IDEALISM  AND  COMMON  SENSE 

566.  These  two  views,  entirely  incompatible  but  often  inter- 
mixed, the  idealist  and  the  common  sense,  carry  with  them 
consequences  that  are  immensely  important  to  the  thinker.  Since 
the  idealist  supposes  that  he  is  aware  of  nothing  but  the  phenomena 
happening  in  his  own  mind,  he  is  unable  to  account  for  their 
appearances,  their  coexistences,  and  their  sequences.1  Even  after 
being  trained  by  common  sense  to  think  coherently,  he  can  do  no 
more  than  observe  and  record  them.  Thus  he  observes  that  in  the 
compound  phenomenon  '  dog '  there  tends  to  coexist  the  subsidiary 
phenomena  canine  trunk,  head,  limbs,  and  tail ;  and  that,  when  the 
phenomenon  dog  has  the  appearance  of  biting  the  phenomenon 
idealist,  there  tends  to  succeed  the  phenomenon  pain  in  the 
phenomenon  leg.  But  he  has  not  the  remotest  idea  why  certain 
phenomena  tend  to  coexist  with  the  phenomenon  canine  body, 
nor  why  the  appearance  of  biting  should  be  followed  by  the 
feeling  of  pain.  He  is,  or  should  be,  bound  by  the  terms  of  his 
philosophy  not  to  pass  outside  the  circle  of  his  own  feelings,  and 
therefore  cannot,  or  at  any  rate  should  not,  explain  the  dog  and 
the  feeling  of  pain  by  the  theory  of  evolution  through  Natural 
Selection.  For,  of  course,  the  notion  of  Natural  Selection  (which 
is  supposed  to  have  occupied  millions  of  years)  occurring  amidst 
the  phenomena,  the  mere  phenomena,  of  his  mind  is  exquisitely 
absurd.  It  is  true  that  most  modern  idealists,  like  most  cultured 
people  whose  culture  is  not  entirely  in  the  air,  are  adherents  of  the 
theory  of  Natural  Selection ;  but  when  they  are  so  they  are 
thinking  in  common-sense  terms,  and  an  absurdity  is  none  the  less 
because  an  inconsistency  is  added.  It  follows  that  all  notions 
of  causation,  in  the  meaning  the  word  ordinarily  bears  in  the 
language,  are  as  inconceivable  to  the  consistent  idealist  as  are 
material  bodies.  For  him  the  word  implies  nothing  more  than 
mere  invariable  succession — not  a  succession  which  is  invariable 
because  it  results  from  the  unvarying  action  on  each  other  of  material 
bodies  which  have  unvarying  properties.  Accordingly  he  declares, 
now  with  some  approach  to  consistency,  that  the  mission  of  science 
something  which  causes  the  common  sensations.  To  me,  on  the  other  hand,  it 
seems  that  we  have  no  title  to  believe  in  other  minds  unless  we  first  believe  in 
real  bodies  external  to  our  own  minds.  That,  moreover,  appears  to  be  the  order 
in  which  the  human  mind  acquires  these  beliefs.  To  this  day,  as  when  giving 
chloroform,  I  draw  my  inferences  about  other  minds  by  the  behaviour  of  what 
I  conceive  to  be  the  material  bodies  associated  with  them. 

1  "  Another  inference,  apparently  more  paradoxical  still,  needs  to  be  made, 
though,  as  far  as  I  am  aware,  Dr  Hodgson  is  the  only  writer  who  has  explicitly 
drawn  it.  That  inference  is  that  feelings,  not  causing  nerve-actions,  cannot  even 
cause  each  other  "  (James,  Principles  of  Psychology,  vol.  i.  p.  133). 


NECESSARY  SUCCESSION  337 

is  merely  to  describe  phenomena  and  record    their  coexistences 
and  sequences. 

567.  On  the  other  hand,  to  the  common-sense  thinker,  who 
supposes  that  both  minds  and  material  bodies  exist  and  that  the 
former  can  be  aware  of  the  latter,  causation  implies  more  than 
mere  invariable  succession.  It  implies  necessary  succession.1 
For,  believing  that  material  bodies  have  properties  or  qualities 
which  bring  them  into  certain  relations  with  one  another,  he 
believes  also  that,  given  these  properties  and  relations,  certain 
consequences  must  follow.  Thus,  though  he  perceives  that  day 
and  night  invariably  succeed  one  another,  yet  he  repudiates  the 
idea  that  they  alternately  cause  each  other.  He  knows  of  no 
property  in  the  one  which  can  cause  the  other.  On  the  contrary, 
he  supposes  that  day  and  night  succeed  because  the  round, 
opaque,  material  earth  rotates  and  so  presents  successive 
parts  of  itself  to  a  luminous  body  the  sun.  Given  these 
conditions,  the  non-occurrence  of  day  and  night  would  be  in- 
conceivable to  him.  Given  the  absence  of  the  opacity  of  the 
earth,  or  of  its  rotation,  or  of  the  luminosity  of  the  sun,  and  he 
would  be  forced  to  believe  that  day  or  night  would  be  eternal, 
though  he  has  no  experience  of  such  a  condition.  A  single 
chemical  experiment  will  convince  him  that  a  certain  substance 
exists  because  two  or  more  elements  have  united  ;  but  no  amount 
of  experience  will  convince  him  that  fine  weather  is  the  cause  of 
the  rain  that  succeeds  it.  In  other  words,  there  is  for  him  a 
distinction  between  post  hoc  and  propter  hoc. 

1  See  §  578. 


22 


CHAPTER  XVIII 
NECESSARY  TRUTH 

Idealism  and  experience — Common-sense  and  experience — Kinds  of  pro- 
perties— The  limits  within  which  we  can  know  and  think — Truths  reached  through 
simple  enumerations — Necessary  truths — Mathematical  axioms — Cause  and  effect 
— Causation  is  a  common-sense  notion — Science  is  common  sense — Thorough- 
going idealism  is  unassailable,  but  leads  to  a  cul-de-sac. 

568.  A  LL  knowledge,  all  thinking  is  founded  ultimately  on 
/\  experience  that  has  been  stored  by  the  memory. 
"*•  -^"  Experience  begins  with  sense-impressions.  The 
one  thing  that  no  one  can  doubt  is  the  existence  of  his  own 
feelings.  There  lies  before  me  what  common-sense  regards  as  a 
sheet  of  paper.  I  may,  after  much  thought,  have  doubts  about 
the  existence  of  that  sheet,  but  I  can  have  none  about  the  existence 
of  the  sensations  that  seem  to  reveal  it  to  me  nor  of  my  thoughts 
about  them.  If  I  think  as  a  thorough-going  idealist,  I  can  note 
these  feelings ;  if  I  go  so  far  as  to  use  the  coherence  of  thought 
that  common  sense  has  established,  I  can  also  observe  and  re- 
member their  co-existences  and  sequences.  But  there  the  matter 
ends.  The  origin  of  them  and  of  their  co-existences  and  sequences 
remains  an  unfathomable  mystery.  On  the  other  hand,  if  I  make 
the  assumption  which  common  sense  makes,  if  I  suppose  that  the 
sheet  has  a  real  existence  external  to  me  and  that  my  feelings 
are  aroused  by  the  properties  or  qualities  of  it,  then  the  matter 
does  not  end  there.  A  limitless  field  of  thought  opens  up.  If  this 
object  has  a  real  existence  and  certain  properties,  then  innumerable 
other  objects  have  real  existences  and  properties  which  are  not 
merely  my  feelings  but  the  exciting  cause  of  them.  Above  all, 
just  as  the  properties  of  the  sheet  of  paper  and  those  of  my  mind 
bring  the  two  things  into  relation,  so  are  all  other  things  brought 
into  relation  by  means  of  their  properties.  In  this  way  the 
universe  is  linked  together  and  becomes  a  unity. 

569.  If,  then,  the  assumption  that  there  is  a  universe  external 
to  my  mind,  and  that  it  is  revealed  to  me  by  my  feelings,  be  given, 
it  follows  that,  though  knowledge  begins  with  sense-impressions, 


THE  PROPERTIES  OF  MATERIAL  OBJECTS        339 

which  reveal  the  qualities  of  things,  it  does  not  end  with  them. 
They  constitute  but  a  minor  part  of  it.  The  main  portion  of  it 
is  reached  through  the  discovery  of  relations,  a  process  which 
involves,  not  merely  perception,  but  thought.  Thus,  through 
thought  we  link  together  dissimilar  impressions  (tactile,  visual, 
etc.)  in  groups  by  recognizing  their  relations  to  one  another,  and 
so,  by  referring  our  impressions  to  the  qualities  of  external  objects, 
construct  our  notions  of  the  latter.  For  example,  we  construct 
the  notion  of  a  sheet  of  paper  by  thinking  that  it  has  certain 
properties.  Facility  in  linking  together  impressions  (i.e.  skill  in 
thinking,  skill  in  perceiving  relations)  is  laboriously  acquired 
during  infancy ;  but  later,  when  the  facility  has  become  so  great 
that  we  accomplish  the  task  without  effort,  we  forget  the  initial 
difficulty  and  are  apt  to  suppose,  with  the  old  school-men,  that  the 
thinking  is  performed  through  intuition.  In  this  way,  also,  we 
learn  the  relations  between  the  various  objects  thus  constructed — 
for  example  between  the  ink,  the  pen,  the  paper,  the  table,  the 
room,  the  house,  the  street,  and  so  on.  Here  again  the  relations 
are  not  all  perceived  at  a  glance,  but  are  thought  out  by  a 
process  that  becomes  more  and  more  complicated,  but  more  facile, 
as  experience  multiplies,  knowledge  increases,  and  skill  grows. 

570.  I  notice  that,  though  the  number  of  objects  in  nature 
appears  to  me  to  be  limitless,  the  number  of  the  different  kinds 
of  properties  they  possess  is  much  smaller.  Objects  have  pro- 
perties in  common,  for  which  reason  we  are  able  to  classify  them. 
I  observe  that  some  properties,  for  instance  extension  in  space 
and  persistence  in  time,  are  possessed  by  all  real  things  within  my 
experience.  Indeed  I  cannot  conceive  a  real  thing  that  does  not 
possess  them.  Others,  for  instance  definite  and  persistent  shape, 
colour,  and  weight  that  I  can  feel,  are  very  common.  Others, 
such  as  certain  colours,  are  rare.  Yet  others,  such  as  a  particular 
shape  or  place  (e.g.  the  precise  shape  and  place  in  the  universe  of 
my  face  at  this  moment),  are  possessed  by  one  object  only. 
Though  the  number  of  the  different  kinds  of  properties  which  I 
can  perceive  are  limited,  yet  they  are  so  numerous  and  may  be 
possessed  by  objects  in  such  varying  degrees  and  combinations 
that  an  infinite  variety  of  objects  is  thereby  rendered  possible. 
Thus  a  beetle  has  some  properties  (e.g.  extension  and  weight)  that 
are  possessed  by  a  house ;  but,  because  some  of  his  properties  (e.g. 
vitality)  differ  from  those  of  the  house  in  kind  while  others  differ 
in  degree,  the  two  objects  are  very  different  and  therefore  dis- 
tinguishable. 


340  NECESSARY  TRUTH 

571.  The  coherent  thinking  of  common  sense  is  founded  on 
these  likenesses  and  differences  between  the  properties  of  things 
and  on  the  fact  that  the  properties  of  all  things  are  conditioned  by 
the   properties   of  other  preceding   or  co-existing  things.     Thus, 
owing  to  some  of  its  properties,  a  certain  object  is  classified  by  the 
postman  as  a  letter,  and,  owing  to  others  is  distinguished  from  all 
similar  objects  as  one  belonging  to  a  certain  person  in  a  certain 
country,  town,  street,  and  house.     The  postman,  the  letter,  and 
the  person  to  whom  it  is  addressed,  have  relations  to  one  another 
which  are  conditioned  by  their  respective  properties.     Now  when 
we  speak  of  cause  and  effect,  what  we  always  mean  is  that  the 
properties  of  a  thing,  or  set  of  things,  are,  or  have  been,  conditioned 
(altered  or  preserved)  by  the  properties  of  another  thing  or  set  of 
things.     Thus,  some  of  the  properties  of  the  letter  (e.g.  its  situa- 
tion) are  altered  by  the  postman  because  he  has  certain  properties 
(e.g.  a  desire  to  perform  his  duty),  and  because  the  person  to  whom 
it  is  addressed  has  certain   properties  (e.g.  a  certain   name   and 
situation).     The  words  in  the  letter  are  preserved   because  the 
paper  on  which  they  are  inscribed  has  the  property  of  prolonged 
persistence. 

572.  If  we  follow  any  line  of  thought  sufficiently  far  we  are 
sure   in  the   end   to   reach   limits   which   mark,   apparently,   the 
beginnings    of  the   unknowable    and   the   unthinkable   (e.g.   the 
nature  of  things  in  themselves,  and  the   terminations,  if  any,  of 
space  and  time).     Nature  is  parsimonious  and  adapts  our  minds, 
like  our  bodies,  to  practical  uses.     But  within   those  limits  ex- 
perience stores  our  memories  with  data  which  enable  us  to  reason. 
All,  or  nearly  all,  our  reasoning  consists  in  a  tracing  of  cause  and 
effect — in  a  tracing  of  how  the  objects  we  think  about  are,  or  have 
been,  or  will  be,  conditioned  by  their  respective  properties.    At  first, 
especially  during  infancy,  we  trace  the  more  obvious  relations. 
But  we  build  continually  on  the  data  thus  gathered  till  our  reason- 
ing, tracing  effects  from  many  combined  causes  or  from  causes  that 
are  far  remote,  grows  increasingly  complex  and  subtle. 

573.  The  limits  within  which  we  can  think  seem  to  be  fixed 
more  by  our  perceptive  than  by  our  thinking  powers.     We  can 
think  only  of  things  that  have  properties  of  the  same  kinds  (ex- 
tension, persistence,  colour,  etc.)  that  we  have  already  perceived. 
Thus,  though  I  can  think  of  a  dragon  or  a  demon  unlike  anything 
that  ever  was  on  land  or  sea,  yet  I  find  I  can  confer  on  it  only 
those    kinds    of   properties,    however    strangely    combined    and 
exaggerated,  that  are  already  known  to  me.    I  am  as  little  capable 


THE  LIMITATIONS  OF  THE  SENSES  341 

of  conceiving  new  kinds  of  properties  as  a  congenitally  deaf  man  is 
of  imagining  sound  or  a  congenitally  blind  man  colour — which  a 
blind  man  once  imagined  to  be  like  the  sound  of  a  trumpet.  Men 
are  sometimes  paralysed  as  regards  sensation  and  movement,  that 
is,  they  lose  in  some  parts  of  their  bodies  the  tactile  and  muscular 
senses.  Conceivably  they  might  be  born  and  might  exist  entirely 
without  them.  Judging  from  the  analogy  of  congenitally  blind 
and  deaf  men,  if  I  had  never  possessed  any  senses  but  those  of 
smell,  taste  and  hearing,  I  could  have  no  idea  of  extension.  So 
slowly  did  I  develop  mentally  after  birth  that  apparently  I  grad- 
ually built  up  my  idea  of  it.  It  was,  therefore,  not  an  intuition, 
an  instinctive  bit  of  knowledge,  but  an  acquirement,  an  induction 
from  experience.  And,  if  my  notion  of  space  was  not  an  intui- 
tion, it  is  hard  to  believe,  so  inconceivable  does  existence  which  is 
not  spatial  now  seem  to  me,  that  I  have  any  other  intuitive  ideas. 
Moreover,  as  we  shall  see  later,  all  ideas  are  founded  on  memory, 
and,  therefore,  cannot  be  intuitive  or  instinctive.  An  instinct  is  a 
mere  impulse  to  action.1 

574.  On  the  other  hand,  I  have  no  doubt  that,  if  I  could  see  the 
colours  that  lie  beyond  the  red  and  violet  ends  of  the  spectrum,  I 
could  think  in  terms  of  them.     Probably,  therefore,  if  a  new  power 
of  perception,  analogous  to   sight  or  hearing   for  instance,  were 
suddenly  conferred  on  me,  my  intellectual  powers  would  suffice  to 
enable  me  to  use  the  materials  provided  by  it  for  purposes  of 
thought. 

575.  It  is  certain  that  our  senses,  even  when  at  their  best,  are 
not  sufficient  to  enable  us  to  perceive  completely  all  the  properties 
of  objects  ;  thus  we  can  see  only  within  a  certain  range  of  the 
spectrum  and  smell  odours  and  taste  flavours  of  a  certain  intensity. 
It  is  practically  certain  that  we  cannot  perceive  at  all  some  of  the 
properties  of  objects ;  thus,  apparently,  a  bat  has  some  sense  lack- 
ing to  us  which  enables  it  to  perceive  some  property  unknown  to 
us,  for  it  is  said  to  be  able  to  avoid  obstacles  when  flying  in  what 
appears  to  us  absolute  darkness.    Again,  we  are  unable  to  perceive 
that  property  in  material  bodies  which  acts  across  apparently  empty 
space,  and  the  effects  of  which  we  term  gravitation.     We  are  able 
to  perceive  only  how  it  affects  the  relations  of  material  bodies  to 
one  another.     It  is  possible  that  all  the  properties  of  some  real 
things  are  altogether  outside  the  range  of  our  perceptions, and,  there- 
fore, that  some  real  things  exist  of  whose  existence  we  cannot  be 
aware  (at  least  directly) — whose  properties  are  inconceivable  to  us. 

1  See  §§  618  et  seq. 


342  NECESSARY  TRUTH 

576.  Our   perceptive  powers  are  mainly  '  innate,'  that  is,  the 
infant  is  born  with  senses  that  do  not  greatly  develop  afterwards 
under  the  stimulus  of  use.     Since,  then,  these  powers  are  '  inherited/ 
we  can  perceive  only  within  that  very  limited  range  within  which 
our   ancestors   perceived.     But   our  thinking  powers  are  mainly 
'  acquirements '  ;  they  develop  under  the  stimulus  of  use  (under 
increase  of  knowledge  and  practice  in  using  it)  to  meet  all  sorts  of 
contingencies ;  and,  therefore,  by  perceiving  different  objects  (not 
different  kinds  of  properties)   and    by   combining  the   materials 
supplied  by  our  perceptions  differently  (by  perceiving  or  imagining 
different  relations)  we  can  think  not  only  in  a  different,  but  often  in 
a  more  far-reaching  way  than  our  ancestors.     Our  sciences  have 
grown  in   this   way.     It  is   not  his  senses^  his  perceptive  powers^ 
but  his  power S)  dependent  on  memory,  of  growing  mentally  under  the 
stimulus  of  use,  that  confers  on  man   his  intellectual  pre-eminence 
over  brutes.     But  of  this  more  anon.1 

577.  I  do   not  know  how  it  happens  that  real  objects   have 
(for  instance)  extension   in  space   and  persistence  in  time.     My 
senses  supply  no  data,  and,  therefore,  in  this  case  also,  I  seem  to 
have  reached  the  limits  of  the  thinkable.     Here  I  cannot  trace 
cause  and  effect;  I  can  only  note  that  all  things  known, to  me  have 
these  properties.     But  the  fact  that  all  the  real  objects  I  have  met 
are  possessed,  in  some  degree,  of  extension  and  persistence,  has 
given  me  the  notion   that  they  are  present   in  all   real  things. 
That  notion,  however,  may  not  be  correct,  for  real  objects  lacking 
them  may  exist  and  I  may  be  unaware  of  them  because  my  senses 
are  incapable  of  being  influenced  by  their  kinds  of  qualities.     It  is 
true  that  we  can  use  a  form  of  words  and  declare  that  a  point  is 
that  which  has  no  magnitude — no  extension ;  but  such  a  point,  a 
thing  without  qualities  that  we  can  perceive,  cannot  really  be  thought 
of.2     We  do  not  conceive  a  new  thing  when  we  use  that  form  of 
words  ;  we  merely  try  to  strip  a  thing  we  know  of  the  qualities  by 
which  we  know  it.     I  seem,  then,  to  have  reached  the  notion  that 
all  real  bodies  have  extension  and  persistence  by  an  induction 
from  a  '  simple  enumeration ' ;  that  is,  I  have  concluded  that  what 
has  always  held  good  within  my  experience  always  would  hold 
good  were   my  experience  universal.     In  the  same  way   I  have 
reached   the  notion  that  all  bodies  in  nature  are  susceptible  of 
movement  (of  having  their  spatial  relations  to  one  another  altered), 
and  the  notion  that  matter  is  impenetrable  (that  no  two  bodies  in 
nature  can  occupy  the  same  part  of  space  at  the  same  instant  of 

1  See  §  624,  et  seq.  *  See  J.  S.  Mill,  Logic t  Bk.  II.  chap,  v.,  §  I. 


KNOWLEDGE  BY  CAUSES  343 

time).  Thus  also  I  have  reached  other  general  notions.  It  seems 
then  that  I  have  gathered  many  notions  of  what  seem  to  me  uni- 
formities in  nature  (Maws'  of  nature)  by  this  process  of  simple 
enumeration.  Such  a  process  is  a  form  of  reasoning,  but  it  is  the 
most  rudimentary  form.  "  This  is  the  kind  of  induction  which  is 
natural  to  the  mind  when  unaccustomed  to  scientific  efforts"1 
"  True  knowledge  is  knowledge  by  causes.  For  that  knowledge 
that  proceeds  by  simple  enumeration  is  a  puerile  thing,  and  con- 
cludes uncertainly,  and  is  exposed  to  danger  from  any  con- 
tradictory instance,  and  for  the  most  part  pronounces  from  fewer 
instances  than  it  ought,  and  of  these  only  from  such  as  are  at 
hand." 2  "  Popular  notions  are  usually  founded  on  induction  by 
simple  enumeration  ;  in  science  it  carries  us  but  a  little  way,  we 
are  forced  to  begin  with  it  ;  we  must  often  rely  on  it  provisionally 
in  the  absence  of  means  of  more  searching  investigation.  But  for 
the  accurate  study  of  nature  we  require  a  surer  and  more  potent 
instrument."  3  It  is  a  remarkable  fact,  however,  that  in  much  recent 
work  (e.g.  in  the  statistical  work  of  idealist  thinkers)  it  is  maintained, 
or  at  least  implied,  that  the  method  of  simple  enumeration  is  the 
only  means  by  which  correct  (and,  therefore,  scientific)  results  can 
be  ensured. 

578.  But,  after  I  have  learned  by  such  enumeration  that  real 
things  have  properties   that  vary   in  kind  and   degree  and  that 
certain  uniformities  exist  in  nature,  I  have  data  that  enable  me  to 
think  in  a  new  way.     I  can  now  say  to  myself,  "Ifit  is  true  that 
real  bodies  exist  and  have  properties  which  bring  them  into  rela- 
tion with  one  another  in  definite  ways,  and  z/it  is  true  that  certain 
uniformities   run   through   nature,  then  given  certain  conditions, 
even   combinations   of  conditions   of  which   I  have  no  previous 
experience,  certain  results  must  follow,  and  can  be  thought  of  by 
me  even  when  I  have  had,  and  can  have  had  no  previous  experience 
of  them.      When  I  think  thus,  I  think  in  terms  of  cause  and  effect, 
and  have  passed  from  the  notion  of  invariable  to  that  of  necessary 
succession.     The  latter  is  not  identical  with  the  former ;  it  is  a 
superstructure  reared  on  it. 

579.  Thus,  after  I  have  acquired  through  experience  definite 
ideas  of  plane  surfaces  and  of  lines  which  are  straight,  perpen- 
dicular, and   parallel,    I    am  able   to   pass   the  bounds  of  direct 
experience   and  declare  that   straight  lines,  on  the   same   plane 
surface  and  perpendicular  to  another  straight  line,  will  never  meet, 

1  Op.  cit.,  Bk.  III.,  chap,  iii.,  §2.  *  Bacon,  Novum  Organon,  i.  105. 

3  J.  S.  Mill,  Logic,  Bk.  III.,  chap,  iii.,  §  2. 


344  NECESSARY  TRUTH 

no  matter  how  far  they  be  produced.  Given  these  real  things 
(surfaces  and  lines),  those  qualities  (plane  and  straight)  and  that 
relation  (perpendicular),  then,  that  other  relation  (parallelism) 
necessarily  follows  and  from  that  also  the  necessary  truth  that 
parallel  straight  lines  will  never  meet — for  the  notion  of  straight- 
ness,  combined  with  that  of  parallelism,  implies  that  lines  having 
that  quality  and  that  relation  will  always  preserve  the  same  distance, 
and,  therefore,  will  never  approach,  and,  therefore,  never  meet.1  It 
matters  not  that  I  have  never  seen  surfaces  that  are  absolutely 
plane  nor  lines  that  are  quite  straight,  perpendicular  and  parellel, 
but  only  surfaces  and  lines  that  nearly  approach  perfection  in 
these  particulars.2  '  Absolutely '  and  '  nearly '  are  relative  terms 
indicating,  not  different  kinds  of  qualities,  but  only  different 
degrees  in  qualities.  Therefore,  when  I  have  experience  of  things 
that  are  nearly  straight,  perpendicular  and  parallel,  I  can  think 
in  terms  of  things  that  are  absolutely  so. 

580.  Again,  I  can  through  direct  experience,  through  actual 
measurement,  reach  the  notion  that  the  three  angles  of  a  certain 
triangle,  which  is  bounded  by  straight  lines  on  a  plane  surface,  are 
equal  to  two  right  angles.     Moreover,  by  repeating  these  observa- 
tions on  other  triangles  I  can,  through  simple  enumeration,  reach 
the  notion  that  what  is  true  of  one  such  triangle  is  probably  true 
of  all  similar  triangles.     But  a  notion  so  reached  will  appear  to  me 
merely  an  expectation,  not  a  necessary  truth.    It  will  only  seem  to  be 
the  latter,  if  I  deduce  it,  as  Euclid  does,  from  the  previously  known 
and  admitted  properties  and  relations  of  lines,  angles  and  triangles. 

581.  In  mathematics  we  are  able  to  discover  many  necessary 
truths,  for  here  the  conditions  are,  speaking  comparatively,  so  little 
complicated  that  we  are  able  to  perceive  and  conceive  things  and 
their   properties    and   relations   with   greater    completeness   and 
certitude  than  elsewhere,  and,  therefore,  can  think  more  exactly 
and  confidently.     Nevertheless,  in  everyday  life  we  are  continually 
endeavouring  to  deduce  such  truths.     That  is,  we  are  continually 
endeavouring  to  deduce  from  the  previously  known  and  admitted 
properties  and  relations  of  things,  effects  that,  given  those  pro- 

1  I  am  informed  by  Professor  H.  H.  Turner  that  much  or  all  of  this  is  con- 
troverted by  the  "  New  Euclidians."     But  the  example  even  if  faulty  will  serve  to 
illustrate  my  meaning.     It  may  be  noted  also  that  in  mathematics  we  do  not 
deal  with  sequences  of  events.    We  suppose,  however,  that,  given  certain  facts, 
certain  other  facts  must  necessarily  be  true  also,  and  we  proceed  to  discover  the 
latter.     The  thinking,  therefore,  is  of  the  same  nature  as  when  we  deal  with 
sequences  of  events — with  cause  and  effect. 

2  See  Mill,  Logic,  II.  v.  147. 


DEDUCTIVE  TESTING  345 

parties  and  relations,  must  follow.  Thus,  given  that  my  cook  has 
certain  properties  (e.g.  the  will  and  the  ability),  given  the  existence 
of  food  in  the  house,  given  a  multitude  of  other  things,  it  follows 
necessarily  that  my  housemaid  will  presently  summon  me  to 
breakfast.  Here,  I  do  not  know  all  the  conditions  as  perfectly  as 
in  geometry,  but,  if  I  did  and  could  think  as  adequately  about  a 
matter  so  complicated,  I  could  be  just  as  sure  in  the  one  case  as 
in  the  other.  The  important  point  is  that  in  this  case  also  I  have 
reached  the  expectation  that  I  shall  be  summoned  to  breakfast 
otherwise  than  by  an  induction  from  a  simple  enumeration  of 
instances  of  former  like  events.  I  could  have  ignored  the  qualities 
of  the  cook  and  the  other  things  concerned  and  reached  the 
expectation  by  remembering  that  I  have  been  so  summoned  for  a 
long  series  of  mornings.  But,  as  a  fact,  I  did  not  do  so.  It  is 
when  we  think  in  terms  of  cause  and  effect  that  the  need  for  test- 
ing our  thinking  by  making  a  deductive  appeal  to  reality  arises. 
Such  a  testing  is  necessary  even  in  the  mathematics  in  which  the 
conditions  are  relatively  simple  and  clearly  defined,  and  the 
chances  of  error  are  correspondingly  slight.  Thus,  when  we 
multiply  one  number  by  another  (e.g.  123  by  345),  we  are  able  to 
make  sure  that  the  product,  the  conclusion  to  which  we  have  led 
by  our  reasoning,  is  correct  only  by  some  such  test  as  is  furnished 
by  dividing  it  by  one  of  the  factors  and  then  ascertaining  whether 
the  quotient  agrees  with  the  other  factor.  The  more  difficult  the 
problem,  the  more  complex  the  conditions  or  the  more  prolonged 
the  chain  of  reasoning,  the  more  necessary  it  is  to  apply  tests ; — 
as  in  biology,  where  the  conditions  are  often  exceedingly  complex 
and  so  obscure  that  it  is  often  difficult  to  separate  essentials 
from  non-essentials,  real  causes  and  effects  from  accidental 
accompaniments. 

582.  In  science,  as  in  everyday  life,  we  endeavour  to  deduce 
effects  from  causes,  or  causes  from  effects,  and  so  link  up  our 
knowledge  in  uniformities,  which,  though  based  ultimately  on 
results  obtained  by  simple  enumeration,  are  other,  and  additional, 
and  as  superior  to  them  as  a  temple  to  its  foundations.  All  the 
sciences  in  which  we  have  succeeded  best  in  this  endeavour  are  the 
most  *  scientific/  the  most  deductive,  the  most  completely  knit  into 
compacted  wholes.1  Mathematics  and  physics  are  examples. 
Zoology  and  botany  formerly  rested  on  a  simple  enumeration  of 
likenesses,  differences,  co-existences,  and  sequences.  Doubt- 
less they  had  practical  uses  and  satisfied  scientific  workers  of  that 
1  See  J.  S.  Mill,  Logic,  II.  iv.  4. 


346  NECESSARY  TRUTH 

class  which  is  content  with  such  a  catalogue  as  a  grocer  makes  of 
his  stock.  But  consider  the  improvement  effected  by  Darwin, 
when,  deducing  necessary  truths  from  given  data,  he  linked 
together  plants  and  animals  by  chains  of  causation.  Knowledge 
was  then  supplemented  by  understanding.  Something  more  than 
a  mere  memory  of  perceptions  came  into  play.  That  something 
was  Reason. 

583.  What,  then,  do  we  mean   by  the  expression  'necessary 
truth  '  ?     How  is  it  to  be  distinguished   from  '  invariable '  occur- 
rence?    A    necessary   truth    is    not   one   reached    by    intuition. 
Apparently  no  such  truths  are  known  to  us.     Nor  is  it  one  reached 
by  induction  from  simple  enumeration ;  for  that  merely  endows  us 
with  a  sense  of  probability,  of  expectancy.     It  is  always  one  which 
we  have  reached  through  what  seems  to  us  valid  reasoning  from  an 
apparently  complete  consideration  of  all  the  relevant  properties  and 
relations  of  real  things.     It  is  not,  of  course,  more  certainly  true 
than  the  existence  of  those  real  things  and  of  their  properties  and 
relations  ;  but,  given  those  existences,  those  properties,  and  those 
relations,  it  is  certainly  true  provided  we  have  reasoned  correctly 
and  taken  all  that  is  essential  into  consideration.     It  is  an  effect 
that  we  have  inferred  from  its  cause,  or  a  cause  that  we  have  in- 
ferred from   its  effect.     It  is  a  conclusion  drawn  from  premises 
antecedently  formulated  or  implied,  and  true  zy  the  premises  are  true. 

584.  If  the  reader  will  try  to  think  of  any  notion  the  truth  of 
which  appears  necessary  to  him,  he  will  always  find  that  it  bears 
this  character  of  an  inference  from  premises  which  have  previously 
been  granted.     For  example,  though  we  are  told  that  every  axiom 
of  geometry  is  a  '  self-evident '  and  *  fundamental '  truth  ;  "  that  is, 
its  truth  should  not  be  deducible  from  any  other  truth  more  simple 
than   itself " ;    yet,   as   a   fact,   we   do,   in   every  instance,  derive 
geometrical  axioms  from  truths  which  we  regard  as  more  funda- 
mental,   simple,    and    self-evident    than    themselves — from    the 
qualities  and  relations  of  the  things  we  are  considering.  Some  reason- 
ing is  always  done  before  we  admit  the  truth  of  an  axiom.     Thus  the 
axiom  that  "  Things  which  are  equal  to  the  same  thing  are  equal 
to  one  another,"  is  but  another  way  of  saying  that  "^things  are 
equal  to  the  same  thing  they  are  equal  to  one  another,  for  the 
reason  that  they  will  then  have  identical  properties  and  relations." 
The  reasoning  may  be  so  swift  and  easy  that  only  more  think- 
ing reveals  its   existence,  so  swift  and  easy  that  an    attempted 
exposition  of  it  appears  like  stating  the  same  thing  in  another  and 
a  more  involved  way  ;  the  inference  may  be  so  obvious  that  only 


THE  NATURE  OF  NECESSARY  TRUTH  347 

careful  consideration  reveals  that  it  is  an  inference ;  but  the  given 
premises,  the  reasoning,  and  the  inference  are  always  there.  An 
axiom  may  seem  self-evident  to  us  who  have  unconsciously  drawn 
the  inference  a  thousand  times  a  day  for  years  ;  but  it  is  not  self- 
evident  to  an  infant  who  must  not  only  acquire  a  knowledge  of 
the  data  on  which  it  is  founded,  but  also  skill  in  thinking  sufficient 
to  enable  it  to  perceive  their  relations  and  how  they  affect  one 
another.1 

585.  To  take  other  examples  ;  we  do  not  regard  a  line  as 
necessarily  straight  unless  we  have  reasons  for  doing  so,  unless  we 
draw  an  inference,  unless  we  think  it  traverses  the  shortest  distance 
between  two  points  and  apprehend  what  that  means.  Uncon- 
sciously we  reason  out  that  a  line  that  does  not  traverse  the 
shortest  distance  cannot  be  straight.  A  straight  line  is  not 
necessarily  perpendicular  to  another  unless  it  makes  equal  angles 
with  it.  Straight  lines  are  not  necessarily  parallel  unless  they  make 
equal  angles  with  a  third  straight  line  on  the  same  plane.  Straight 
lines  on  the  same  plane  will  necessarily  meet  if  produced  far 
enough  unless  they  are  parallel.  Evolution  through  Natural 
Selection  may  be  true  ;  but  it  is  not  necessarily  true  unless  off- 
spring resemble  their  parents  on  the  whole  but  differ  from  them 
in  details,  unless  they  outnumber  them,  unless  only  the  fittest 
survive  on  the  average,  unless  the  fittest  belong  to  types,  and  so 
on.  In  brief,  for  us  a  necessary  truth  is  always  an  effect  or  cause 
which  we  have  been  able  to  trace  so  perfectly  to  its  cause  or 
effect  that  no  doubt  of  the  nature  and  reality  of  the  connexion 
remains  in  our  mind.  It  is  a  truth  which  we  think  we  not  only 

1  Dr  Whewell  and  others  have  held  that  "it  is  not  experience  which  proves 
the  axiom  ;  but  that  its  truth  is  perceived  a  priori  by  the  constitution  of  the 
mind  itself,  from  the  first  moment  when  the  meaning  of  the  proposition  is 
apprehended,  and  without  any  necessity  of  verifying  it  by  repeated  trials,  as  is 
requisite  in  the  case  of  truths  really  ascertained  by  observation  "  (Mill,  Logic,  v.  4). 
This  view  is  opposed  by  Mill  who  thinks  that  we  learn  the  truth  of  axioms  wholly 
through  experience.  The  two  opinions  do  not  appear  to  be  absolutely  contra- 
dictory. Whewell  admits  that  we  must  have  experience — that  the  meaning  of 
propositions  and  all  that  that  implies  in  the  way  of  experience,  must  be  appre- 
hended. Mill  admits  as  necessary  truths  those  "  necessarily  following  from 
hypothesis."  I  think  I  learned  originally  through  experience  that  two  halves 
make  a  whole  ;  but  now  that  I  have  learned  "  the  meaning  of  the  proposition  " 
I  hold  that  belief  on  other  grounds  as  a  necessary  truth.  In  this  way,  at  first 
mere  experience  led  me  to  believe  in  the  mathematical  axioms  and  most  of  the 
other  necessary  truths  that  I  now  hold  as  such  ;  but  they  did  not  become  necessary 
truths  to  me  till  I  had  reached  them  in  another  way.  The  view  I  suggest  differs 
from  those  of  Whewell  and  Mill  in  that  axioms,  as  such,  seem  to  me  products  of 
reasoning,  not  of  intuition  or  of  mere  repeated  experience. 


348  NECESSARY  TRUTH 

know,  but  which  we  think  we  can  account  for  in  terms  of  other 
admitted  truth.  Moreover,  it  is  always  a  truth  which  has  been 
or  which  can  be  reached  otherwise  than  by  simple  enumeration 
and  which,  therefore,  can  be  tested  in  one  or  more  ways,  for 
example  by  simple  enumeration.  Thus,  after  declaring  that, 
given  certain  conditions  (e.g.  universal  gravitation,  the  rotating 
earth,  and  the  moon),  a  certain  result  must  follow  (e.g.  the  tides), 
we  can  test  our  supposed  necessary  truth  by  appealing  to  instances 
which  occur  in  reality.  Therein  it  differs  from  a  truth  which  as 
yet  has  been  and  can  be  founded  only  on  simple  enumeration  (e.g. 
the  statement  that  all  real  bodies  have  extension) ;  for  such  a  truth, 
which  has  not  been  deduced  from  any  other,  can  be  tested,  if  that 
deserves  to  be  called  testing,  only  by  continuing  the  enumeration. 
586.  We  see  then  that  a  necessary  truth  is  one  which  we  have 
reached  by  tracing  the  relation  of  cause  and  effect.  We  observe 
that  certain  bodies  in  nature  have  certain  properties  or  qualities, 
for  example  extension  and  gravity,  by  means  of  which  they  are 
brought  into  relation  with  one  another  and  so  affect  one  another. 
A  law  of  nature  is  a  uniformity  that  we  have  observed  in  nature. 
Usually  we  mean  by  the  term  a  uniformity  of  sequence ;  that  is,  a 
uniformity  in  the  way  in  which  bodies  affect  one  another.  Uni- 
formities of  sequences  imply  uniformities  of  qualities  and  relations, 
and,  therefore,  of  consequences.  Doubtless,  it  is  this  notion  of 
necessary  consequences  that  has  given  rise  to  the  term  '  law.' 1 
Thus,  if  it  be  true  that  material  bodies  attract  one  another,  it  must 
be  true  also  that  they  tend  to  approach  one  another.  A  necessary 
truth  is  merely  a  particular  instance  of  a  general  uniformity,  or 
else  it  is  a  consequence  correctly  deduced  from  such  a  uniformity. 
When  we  formulate  such  a  truth,  we  declare,  in  effect,  "  If  the 
general  law  is  true,  then,  since  the  bodies  we  are  considering  have 
qualities  and  relations  that  bring  them  within  the  range  of  that 
law,  this  particular  instance  or  consequence  of  it  must  be  true  also." 
In  practice  the  term  necessary  truth  is  used,  as  a  rule,  in  cases  in 
which  the  inference  is  not  very  obvious — in  cases  in  which  conse- 
quences rather  than  instances  are  dealt  with,  in  which  more  than 
one  quality  and  relation  and  therefore  more  than  one  uniformity  is 
concerned,  and  in  which,  therefore,  the  conclusion  is  reached  by 
1  "  A  law,  then,  in  the  strict  scientific  sense  is  a  fully  established  statement 
of  universal  and  necessary  connexion  .  .  .  more  loosely,  the  term  is  frequently 
used  to  denote  mere  empirical  generalizations.  .  .  .  These,  however,  express  no 
necessity  and,  consequently,  are  not  laws  in  the  strict  sense  .  .  .  '  empirical  law  ' 
is,  correctly  speaking,  almost  a  contradiction  in  terms."  (Wei ton,  Manual  of 
Logic,  vol.  ii.  p.  200.) 


INTERPRETATION  349 

reasoning  that  is  more  or  less  complex  or  prolonged.  The  declara- 
tion that  a  conclusion  is  a  necessary  truth  amounts  to  a  claim  that 
we  have  reasoned  correctly  from  premises  (law  or  laws)  that  are 
admittedly  true.  No  matter  how  simple  or  complex  the  case, 
when  we  declare  that  we  have  '  explained '  or  '  understood '  an 
occurrence,  we  mean  merely  that  we  have  interpreted  it  in  terms  of 
one  or  more  uniformities  of  which  we  are  aware.  Moreover,  this 
tracing  of  instances  and  consequences  to  general  uniformities,  and 
therefore  to  the  qualities  and  relations  of  objects,  is  all  that  we 
mean  by  '  tracing  a  chain  of  causation.'  Thus,  knowing  the 
common  uses  of  pokers  and  that  iron  can  be  raised  to  a  high 
temperature  by  fire,  we  explain  the  hotness  of  a  poker,  we  describe 
the  cause  of  the  hotness,  by  saying  that  the  poker  has  been  in  the 
fire.  On  the  other  hand,  knowing  the  qualities  of  ice,  we  should, 
if  we  found  a  hot  piece  of  it,  be  at  a  loss  for  an  explanation. 
Knowing  that  intact  brains  are  essential  to  the  existence  of  human 
beings,  we  suppose  we  have  the  explanation  of  the  death  of  a  man 
when  we  discover  a  bullet  imbedded  in  his  brain.  We  explain  the 
rise  of  the  tide  and  the  fall  of  a  stone  by  the  same  law.  We  ex- 
plain the  rise  and  fall  of  water  in  a  harbour  by  the  tides  of  the 
ocean,  the  tides  by  the  influence  of  the  moon,  the  influence 
of  the  moon  by  the  law  of  gravitation.  We  cannot  as  yet 
explain  the  law  of  gravitation  by  reference  to  a  wider 
uniformity ;  it  is  for  us  an  ultimate  law ;  but  between  it  and  the 
rise  and  fall  of  water  in  a  harbour  lies  a  chain  of  explanation,  of 
causation,  and  of  necessary  truth.  When  Huxley  declared  that, 
"  Fact  I  know  :  and  law  I  know :  but  what  is  this  Necessity,  save 
an  empty  shadow  of  my  own  mind's  throwing  ? " 1  he  referred 
to  these  ultimate  uniformities  which  as  yet  we  cannot  explain, 
and  which  perhaps  we  shall  never  be  able  to  explain  by  reference 
to  more  general  laws.  He  referred  to  necessary  truth  when  he 
said  "  even  thoughtful  men  usually  receive  with  surprise  the 
suggestion,  that  the  form  of  the  crest  of  every  wave  that  breaks, 
wind-driven,  on  the  sea-shore,  and  the  direction  of  every  particle  of 
foam  that  flies  before  the  gale,  are  the  exact  effects  of  definite 
causes;  and,  as  such,  must  be  capable  of  being  determined, 
deductively,  from  the  laws  of  motion  and  the  properties  of  air  and 
water."  2  "  The  very  postulate  of  knowledge  compels  us  to  think 
every  variation  and  every  detail,  even  the  smallest,  as  so  deter- 
mined by  conditions  that,  under  the  circumstances,  it  could  not 
possibly  be  other  than  it  is.  When  the  conditions  of  every  detail 
1  Essays,  vol.  i.  p.  161.  8  Hume,  p.  122. 


350  NECESSARY  TRUTH 

of  a  phenomenon  are  so  fully  and  exactly  known  that  not  only 
a  phenomenon  of  this  general  character,  but  just  this  very 
phenomenon,  with  exactly  these  details,  and  each  in  exactly  this 
amount,  must  follow  from  those  conditions,  and  from  those  only, 
then  that  phenomenon  is  fully  explained."  l  But  when  we  think 
of  necessary  truth,  we  must  do  so  in  terms  of  that  reality  to  which 
our  minds  seem  to  testify.  If  we  question  the  reality,  we  can 
declare,  "  Fact  I  doubt :  and  law  I  doubt :  and,  therefore,  necessity 
I  doubt."  But,  given  the  fact  and  law,  then  necessity  is  beyond 
all  doubt. 

587.  When  tracing  cause  and  effect,  we  do  not  refer  explicitly 
to  all  the  qualities  of  the  objects  we  are  considering.     Every  object 
has  many  qualities.     Thus  iron  has  persistence  in  time,  extension 
in  space,  weight,  colour,  frangibility,  ductility,  hardness,   and   a 
multitude  of  others.     It  could  not  become  hot,  it  could  not  even  be 
an  object  for  us,  unless  it  had  at  least  many  of  them,  for  example, 
persistence  and  extension,  yet  we  do  not  think  or  say  that  the 
poker   becomes   hot   because   it   has   persistence   and   extension. 
Many  pokers  are  not  hot ;  even  ice  which  cannot  become  hot  has 
persistence  and  extension.     We  refer  especially  to  the  quality  in 
iron,  its  temperature,  which  is  changed  by  the  fire,  and  the  quality  in 
the  fire  which  is  concerned  in  the  change.     The  last  is  termed  the 
cause,  the  change  in  the  first  is  termed  the  effect 

588.  More  than  one  quality  may  be  concerned  in  a  cause  ;  thus 
both  the  momentum  and  the  hardness  of  a  bullet  are  concerned  in 
the  effect  produced  when  it  strikes  another  body.     More  than  one 
quality  may  be  concerned  in  an  effect ;  thus  the  position,  shape, 
and  temperature  of  a  piece  of  iron  may  be  changed  when  it  is 
struck.     Nevertheless,  no  matter  how  many  of  the  qualities  of  an 
object  are  concerned  when  it  acts  on  or  is  acted  on  by  another  object, 
in  practice  we  think  only  of  those  which  are  especially  concerned  ; 
or  indeed,  only  of  those  of  with  which  we  are  especially  concerned. 
Of  course,  no  cause  or  effect  stands  isolated  in  the  external  world  \ 
we  merely  isolate  it  in  thought.     In  reality  it  is  connected  not  with 
a  chain,  but  with  a  circle  of  cause  and  effect.     Thus  a  bullet,  on 
which  certain  properties  were  conferred  during  manufacture,  flies 
because  it  is  impelled  by  the  explosion  of  powder,  ignited  by  a 
spark  in  a  gun,  which  was  fired  because  a  man,  who  was  present 
through    a    concatenation   of   circumstances    that   reaches   back 
through  eternity,  pulled  a  trigger  because  he  was  made  angry  by 
certain  events,  and  so  on.     Yet  we  say  only  that  the  one  man  was 

1  Welton,  Manual  of  Logic,  vol.  ii.  p.  188. 


THE  NOTION  OF  CAUSATION  351 

shot  because  he  angered  the  other  man.  A  knowledge  of  the 
whole  circle  of  causation  would  imply  perfected  science,  a  thorough 
knowledge  and  understanding  of  the  whole  universe  during  all  past 
time.  In  a  sense,  at  any  instant,  we  can  point  to  the  termination 
of  effect,  for  at  any  instant  the  effect  has  not  proceeded  beyond 
that  instant;  but  the  circle  of  causation  had  its  beginnings  only  in 
the  beginnings,  if  any,  of  time  and  space.  But  this  totality,  both 
when  we  consider  the  qualities  of  objects,  and  the  circle  of 
causation,  is  utterly  unwieldy.  Therefore,  as  in  practice  we  select 
for  purposes  of  thought  certain  qualities  of  objects,  so  also  when 
tracing  causation  we  select  certain  parts  of  the  circle.  We 
suppose  a  chain,  and,  even  then,  think  only  of  those  links  that 
appear  to  serve  our  purpose  best. 

589.  In  this  way,  by  supposing  that  objects  have  reality  out- 
side  our   minds,  and  by  supposing   that  they  have   qualities  by 
means  of  which  they  act  and  react  on  one  another  in  a  uniform 
way,  we  gather  the  notion  of  a  universe  which,  so  far  from  being 
chaotic,  is   orderly   to   its   minutest  details ;  and  in  reference  to 
which,  as  far  as  we  are  able  to  perceive  the  order  and  trace  cause 
and  effect,  we  are  able  to  use  such  words  as, '  understand,' '  explain/ 
1  why,'   '  reason,'  and  the  like  with  intelligible  meanings.     If  we 
did  not,  and  more  especially  if  we  had  not,  supposed  a  material 
universe,   our    thoughts,   as    we    have    seen,   would   be    without 
coherence.     Or    rather,    we   would    have   no   thoughts,   but   only 
feelings.     Very  emphatically,  then,  the  entire  notion  of  causation 
belongs  wholly  to  common  sense.     It  has,  or  should  have,  no  place 
in  idealist  thinking. 

590.  All    science,   like   all   ordinary   thinking,  is   founded   on 
common  sense.     "  Every  science  assumes  certain  data  uncritically, 
and   declines  to  challenge  the   elements  between  which  its  own 
*  laws '  obtain  and  from  which  its  deductions  are  carried  on.  ... 
Of  course  these  data  are  themselves  discussable,  but  the  discussion 
of  them  (as  of  other  elements)  is  called  metaphysics."  x     That  is, 
every  science  thinks  in  terms  of  what  are  supposed  to  be  real 
existences  and  omits  to  discuss  the  question  whether  they  are,  or 
are  not,  real,     "  All  physical  science  starts  from  certain  postulates. 
One  of  them  is  the  objective  existence  of  a  real  world."  2    It  is  true 
that  we  are  told  that  "  a  scientific  law  is  related  to  the  perceptions 
and  conceptions  formed  by  the  perceptive  and  reasoning  faculties  in 
man  ;  it  is  meaningless  except  in  association  with  these ;  it  is  the 

1  James,  Principles  of  Psychology,  Preface,  v-vi. 

2  Huxley,  Essays,  vol.  iv.,  p.  60. 


352  NECESSARY  TRUTH 

resume  or  brief  expression  of  the  relations  and  sequences  of  certain 
of  these  perceptions  and  conceptions,  and  exists  only  when 
formulated  by  man.1  .  .  .  The  law  of  gravitation  is  not  so  much 
the  discovery  by  Newton  of  a  rule  guiding  the  motion  of  the 
planets  as  his  invention  of  a  method  of  briefly  describing  the 
sequences  of  sense-impressions,  which  we  term  planetary  motion.  .  .  . 
We  are  thus  to  understand  by  a  '  law  of  nature,'  a  resumed  mental 
shorthand,  which  replaces  for  us  a  lengthy  description  of  the 
sequences  among  our  sense  impressions."  2  According  to  the  law 
of  gravitation,  all  bodies  in  nature  attract  each  other  proportion- 
ately as  their  masses  andjnversely  as  the  squares  of  their  distances. 
Now  in  what  intelligible  sense  can  the  sense-impression,  the  earth, 
be  said  to  attract  the  sense-impression,  the  sun  ?  What  are  their 
masses,  and  what  the  squares  of  their  distances  ?  To  all  appear- 
ances the  planets,  the  sun,  and  the  other  stars  are  of  no  great 
magnitudes,  at  no  great  distances,  and  float  lighter  than  feathers 
through  the  air.  Even  if  they  be  conceived  as  nothing  more  than 
sense-impressions  between  which,  after  a  previous  training  by 
common  sense,  Newton  was  able  to  discover  relations  which  are 
quite  unlike  their  apparent  relations,  how  do  we  know  that  Newton 
existed  as  a  thinking  entity?  As  a  fact,  the  law  of  gravitation 
has  been  accepted  by  astronomers  and  physicists  as  describing  a 
relationship  between  material  bodies  external  to  the  human  mind 
— bodies  and  a  relationship  between  them  which  the  human  mind  is 
thought  to  be  aware  of  at  present,  but  which  existed  long  before 
the  evolution  of  any  such  mind.  Obviously  also,  since  the  word 
1  attraction '  is  used,  the  relationship  indicated,  as  in  the  case  of 
many  other  laws  that  have  been  formulated,  is  one  of  causation. 
It  is  not  a  mere  invariable  succession  such  as  that  of  night  and 
day,  the  notion  of  which  is  reached,  not  through  a  consideration 
of  the  qualities  of  the  related  objects,  but  through  simple  enumera- 
tion. I  say  '  formulated,'  for  the  laws  that  are  reached  through 
simple  enumeration  (e.g.  the  law  that  all  material  bodies  have 
extension),  are,  as  a  rule,  discovered  by  every  one  and  therefore 
are  not  worth  formulating  by  anyone. 

591.  "  In  the  scientific  sense,  a  law  is  a  statement  of  a  necessary 
connexion ;  it  is  not  something  imposed  upon  reality  from  without, 
but  is  the  outcome  of  the  nature  of  reality  itself.  The  perception 
of  natural  laws  is  due,  no  doubt,  to  the  synthetic  activity  of  mind, 
but  it  is  possible  only  because  the  connexion  actually  exists  in 
reality.  It  is  because  the  world  is  a  systematic  unity  that  we  are 
1  Pearson,  Grammar  of  Science,  ed.  1900,  p.  82.  z  Op.  ctt.,  p.  86-7. 


SCIENTIFIC  MATERIALISM  353 

compelled  to  think  it  as  such.  A  law,  then,  in  the  strict  scientific 
sense,  is  a  fully  established  statement  of  universal  and  necessary 
connexion." l  As  a  simple  matter  of  fact,  no  chemist,  astronomer, 
zoologist,  botanist,  or  medical  man,  for  example,  ever  does,  under 
his  ordinary  conditions  of  thought,  conceive  elements,  worlds, 
animals,  plants,  or  human  beings,  as  groups  of  his  private  feelings. 
They  are  to  him  concrete  realities  existing  external  to  himself, 
and  a  principal  part  of  his  labours  is  to  gather  information  from 
and  impart  it  to  other  concrete  people.  It  is  just  this  fact  that 
science,  in  more  senses  than  one,  is  "  organized  common  sense  " 
that  imparts  to  it  its  intellectual  richness  and  splendour,  that 
rescues  it  from  the  intellectual  leanness,  meanness  and  barrenness 
of  the  grocer's  catalogue. 

592.  Nevertheless,  though  idealism  is  possible  only  to  the  man 
who  has  learned  to  think  in  terms  of  common  sense,  though  it  is 
utterly  unable  to  advance  beyond  the  fact  that  his  feelings  exist, 
though  the  idealist  philosopher  can  do  nothing  but  wonder  im- 
potently,  its  position  seems  quite  unassailable.  That  is,  the 
position  of  through-going  idealism  seems  quite  unassailable.  That 
kind  of  idealism  which  uses  the  whole  paraphernalia  of  common 
sense,  which  appeals  to  the  phenomena  that  common  sense  has 
compounded  and  so  rendered  coherent  and  to  other  minds,  which 
is  idealist  only  during  occasional  asides  when  it  proclaims  itself 
idealist,  that  kind  is  assailable  at  every  joint.  It  is  only  a  tour  de 
force  by  people  who  in  their  appeals  to  other  people  assume  the 
very  thing  they  profess  to  deny.  To  sum  up  :  my  own  attitude — 
I  must  be  egotistical  when  I  speak  in  terms  of  idealism — is  this ; 
I  admit  I  cannot  pass  beyond  the  circle  of  my  feelings,  which  may 
lie  to  me,  or  which,  if  they  tell  the  truth,  can  tell  it  only  in  a 
symbolic  way.  I  do  not  positively  know  that  there  is  a  universe 
external  to  my  consciousness  in  which  exist  material  objects  and 
minds  like  my  own,  which  know  or  can  know  the  things  that  I 
know.  But,  having  made  that  admission,  I  return  wholly,  or 
almost  wholly,  to  common  sense,  which  has  rescued,  and  still 
rescues,  me  from  mental  impotence.  I  assume  that  the  universe 
exists  as  a  reality,  and  that  my  feelings,  and  those  of  other  people, 
symbolize  it  much  as  written  words  symbolize  spoken  words. 
I  suppose  that  the  real  things  of  which  the  universe  is  constituted 
have  properties  which  bring  them  into  relation  with  one  another, 
and  that  thence  arise  relations  of  cause  and  effect,  and  ultimately 
my  notions  of  necessary  truth.  I  can  test  the  evidence  furnished 

1  Welton,  Manual  of  Logic,  vol.  ii.  p.  200. 
23 


354  NECESSARY  TRUTH 

by  common  sense  in  so  many  ways,  and  if  the  tests  are  conducted 
with  sufficient  care,  I  so  invariably  find  the  evidence  consistent 
with  itself,  that  it  seems  to  me  highly  probable  that  my  assump- 
tions are  correct  As  to  the  actual  nature  of  the  reality  which  I 
think  my  mind  symbolizes,  I  make  no  guess.  I  use  the  word 
1  matter,'  but  only  as  a  convenient  name  for  a  something  of  which 
I  have  no  immediate  knowledge.  Since  I  suppose  that  my  mind 
symbolizes  reality,  I  suppose  also  that  the  uniformities  which  I 
detect  in  nature  are  due  to  a  uniformity  of  causation  which 
depends  on  the  qualities  and  relations  of  material  objects,  not  on 
a  mere  invariable  and  utterly  unaccountable  succession  of  mental 
happenings,  which  is  all  that  the  idealist  has  a  right  to  postulate. 
Therefore,  though  I  do  not  know  the  whole  circle  of  causation, 
but  only  a  little  part  of  it,  yet,  within  the  narrow  limits  of 
my  knowledge,  the  universe  appears  to  be  comprehensible,  and 
I  am  able  to  say  that  I  understand  and  can  explain.  I  am, 
then,  in  one  respect,  an  idealist,  and  in  another  a  materialist. 
I  am  an  idealist  in  that  I  know  I  know  my  feelings,  but 
nothing  else.  I  am  a  materialist  in  that  I  believe  my  feelings 
symbolize  reality.  My  attitude  differs  from  the  common  sense  of 
everyday  life  and  of  science  (which  accepts  appearances  for  what 
they  seem  to  be)  in  this  matter  of  symbolism.  I  suppose  I  am 
like  a  man  who  is  deaf,  and  knows  that  he  is  deaf,  but  who  can 
read.  I  am  not  like  a  deaf  man,  who,  being  able  to  read,  supposes 
that  he  can  hear,  or,  at  the  other,  the  idealist,  extreme,  like  one 
who,  being  able  to  read,  supposes  he  can  neither  hear  nor  read. 

593.  Granting  the  existence  of  material  objects,  then  evidently 
there  are  two  distinct  ways  in  which  we  may  classify  facts, 
and  so  create  science.  On  the  one  hand,  we  may  arrange  our 
data  accordingly  as  the  objects  we  have  under  consideration 
have,  or  have  not,  properties,  or,  as  they  are  termed  in  biology, 
*  characters,'  in  common.  Thus,  since  a  man  possesses  certain 
characters  in  common  with  other  living  beings,  we  classify  him 
as  an  animal,  a  vertebrate,  a  mammal,  and  so  on.  In  this  way 
systematic  zoology,  botany,  and  anatomy  have  been  developed. 
Here  the  mental  faculties  we  employ  are  principally  observation, 
recollection,  comparison,  and  the  like.  On  the  other  hand,  we 
may  arrange  our  facts  in  chains  of  causation.  This  is  the 
method  adopted  in  mathematics,  physics,  to  a  great  extent  in 
astronomy,  and  in  biology  when  we  discuss  problems  of  heredity 
and  evolution.  Here,  regarding  the  properties  of  objects  as  causes 
or  effects,  we  proceed  principally  by  formulating  hypotheses,  which 


KINDS  OF  THINKING  355 

we  test  and  establish  (or  disprove)  by  making  a  deductive  appeal 
to  reality.  In  other  words  we  reason.  The  kind  of  thinking 
employed  in  the  one  case  differs  sharply  from  that  employed  in 
the  other.  For  example,  if  a  systematic  botanist  wishes  to 
demonstrate  the  truth  of  a  disputed  statement,  his  main  task,  as 
a  rule,  is  to  prove  the  correctness  of  the  data  from  which  he 
starts  his  thinking.  In  other  words,  he  has  to  demonstrate  that 
he  has  observed,  recollected,  and  compared  correctly ;  for,  while 
his  facts  are  often  multitudinous  and  complex,  the  thinking 
founded  on  them  is  usually  relatively  simple,  and  therefore 
unlikely  to  be  wrong  if  the  facts  are  correct.  The  mathematician, 
on  the  contrary,  usually  founds  thinking  that  is  relatively  diffi- 
cult on  facts  that  are  comparatively  simple.  His  main  task  is  to 
prove  the  correctness  of  his  reasoning.  We  shall  see  later  that 
skill  in  thinking,  whether  of  the  kind  employed  by  the  systematist 
or  that  which  is  used  by  the  mathematician,  is  an  '  acquirement.' 
It  develops  under  the  stimulus  of  use.  Moreover,  skill  in  the  one 
kind  of  thinking  does  not  necessarily  imply  skill  in  the  other  kind. 
No  one  disputes  that  we  have  created  true  science  when  we  have 
arranged  our  facts  *  systematically.'  Nor  has  any  one  ventured  to 
deny  that  mathematics  and  physics,  in  which  causal  relations  are 
traced,  are  products  of  real  scientific  thought.  Occasionally, 
however,  a  biologist,  while  neither  denying  the  facts  nor  contro- 
verting the  thinking  founded  on  them,  denounces  '  speculation  ' 
and  '  theorizing.' 1  It  is  unscientific,  of  course,  to  found  speculations 
on  imaginary  facts  or  formulate  guesses  which  are  incapable  of 
proof  or  disproof;  and,  certainly,  hypotheses  of  this  kind  are  not 
uncommon  in  biology.  But,  judging  from  the  language  sometimes 
used,  it  is  not  merely  the  faulty  use  of  a  right  method  of  work 
that  is  condemned,  but  the  method  itself.  Manifestly,  however,  if 
it  be  possible  to  link  facts  in  chains  of  causation,  it  is  proper  to  do 
so.  Knowledge  is  then  supplemented  by  more  knowledge,  and  by 
understanding  besides,  and  the  structure  of  science  is  all  the  more 
complete  because  we  have  added  the  woof  to  the  warp  of  it. 
Since  verified  facts  are  abundant  in  biology,  and  since  as  living 
beings  we  are  familiar  with  the  conditions  of  life,  it  should  not  be 
beyond  the  powers  of  the  human  intellect,  which  has  discovered 
the  calculus  and  the  law  of  gravitation,  to  indicate  in  general 
terms  the  uniformities  of  sequence  under  which  the  structures  of 
plants  and  animals  have  arisen.  At  any  rate  the  attempt  to  do  so 
is  not  unscientific.2 

1  See  §  826.  *  See  §§  828,  et  seq. 


CHAPTER   XIX 
THE   RELATION   OF   MIND   TO   BODY 

Huxley  and  Clifford — Their  inconsistencies — Mind  and  body  are  causally 
related — Professor  William  James — Theories  of  the  relation  of  Mind  to  Body — 
Probably  mind  is  the  work  done  by  the  brain — The  bodies  of  human  progenitors 
and  descendants  are  more  closely  alike  than  their  minds. 


R 


594.  |  ^  ETURNING  now  altogether  to  the  thinking  of  every- 
day life  and  of  science,  common  sense  tells  us 
that  we  have  minds  and  bodies,  and  that  these 
two  sharply  distinct  things  influence  one  another — have  causal 
relations  with  one  another.  This  causal  relation  has  been  denied, 
however,  and  sometimes  on  very  high  authority. 

"The  consciousness  of  brutes  would  appear  to  be  related  to 
the  mechanism  of  their  body  simply  as  a  collateral  product  of  its 
working,  and  to  be  as  completely  without  any  power  of  modifying 
that  working  as  the  steam-whistle  that  accompanies  the  work  of  a 
locomotive  engine  is  without  influence  on  its  machinery.  Their 
volition,  if  they  have  any,  is  an  emotion  indicative  of  physical 
changes,  not  a  cause  of  such  changes.  .  .  .  Much  ingenious  argu- 
ment has  at  various  times  been  bestowed  on  the  question.  How 
is  it  possible  to  imagine  that  volition,  which  is  a  state  of  conscious- 
ness, and,  as  such,  has  not  the  slightest  community  of  nature  with 
matter  in  motion,  can  act  upon  the  moving  matter  of  which  the 
body  is  composed,  as  it  is  assumed  to  do  in  voluntary  acts  ?  But 
if,  as  is  here  suggested,  the  voluntary  acts  of  brutes — or,  in  other 
words,  the  acts  which  they  desire  to  perform — are  as  mechanical 
as  the  rest  of  their  actions,  and  are  simply  accompanied  by  the 
state  of  consciousness  called  volition,  the  inquiry,  so  far  as  they 
are  concerned,  becomes  superfluous.  Their  volitions  do  not  enter 
into  the  chain  of  causation  of  their  actions  at  all.  .  .  .  The  soul 
stands  related  to  the  body  as  the  bell  of  a  clock  to  the  works, 
and  consciousness  answers  to  the  sound  the  bell  gives  out  when 
it  is  struck.  .  .  .  Thus  far  I  have  strictly  confined  myself  to  the 
automatism  of  brutes.  ...  It  is  quite  true  that,  to  the  best  of  my 
judgment,  the  argumentation  which  applies  to  brutes  holds  equally 

356 


THE  AUTOMATON  HYPOTHESIS  357 

good  for  man  ;  and,  therefore,  that  all  states  of  consciousness  in 
us,  as  in  them,  are  immediately  caused  by  molecular  changes  of 
the  brain-substance.  It  seems  to  me  that  in  men,  as  in  brutes, 
there  is  no  proof  that  any  state  of  consciousness  is  the  cause  of 
change  in  the  motion  of  the  matter  of  the  organism. 

"  If  these  positions  are  well  based,  it  follows  that  our  mental 
conditions  are  simply  the  symbols  in  consciousness  of  the  changes 
which  take  place  automatically  in  the  organism  ;  and  that,  to 
take  an  extreme  illustration,  the  feeling  we  call  volition  is  not 
the  cause  of  a  voluntary  act,  but  a  symbol  of  that  state  of  the 
brain  which  is  the  immediate  cause  of  the  act.  We  are  conscious 
automata."1 

595.  "All  the  evidence  that  we  have  goes  to  show  that  the 
physical  world  gets  along  entirely  by  itself,  according  to  practi- 
cally universal  rules.  .  .  .  The  train  of  physical  facts  between 
the  stimulus  sent  to  the  eye,  or  to  any  one  of  our  senses,  and  the 
exertion  which  follows  it,  and  the  train  of  physical  facts  which 
goes  on  in  the  brain,  even  when  there  is  no  stimulus  and  no  exer- 
tion— these  are  perfectly  physical  trains,  and  every  step  is  fully 
accounted  for  by  mechanical  conditions.  .  .  .  The  two  things  are 
on  utterly  different  platforms — the  physical  facts  go  along  by 
themselves,  and  the  mental  facts  go  along  by  themselves.  There 
is  a  parallelism  between  them,  but  no  interference  of  one  with  the 
other.  Again,  if  anybody  says  that  the  will  influences  matter, 
the  statement  is  not  untrue,  but  it  is  nonsense.  Such  an  assertion 
belongs  to  the  crude  materialism  of  the  savage.  The  only  thing 
which  influences  matter  is  the  position  of  surrounding  matter,  or 
the  motion  of  surrounding  matter.  .  .  .  The  assertion  that  another 
man's  volition,  a  feeling  in  his  consciousness  which  I  cannot 
perceive,  is  part  of  the  train  of  physical  facts  which  I  can  perceive 
— this  is  neither  true  nor  untrue,  but  nonsense ;  it  is  a  combination 
of  words  whose  corresponding  ideas  will  not  go  together.2  .  .  . 
Sometimes  one  series  is  known  better,  and  sometimes  another ;  so 
that  in  telling  a  story  we  speak  sometimes  of  mental  and  some- 
times of  material  facts.  A  feeling  of  chill  made  a  man  run  ; 
strictly  speaking,  the  nervous  disturbance  which  coexisted  with 
that  feeling  of  chill  made  him  run,  if  we  want  to  talk  about 
material  facts  ;  or  the  feeling  of  chill  produced  the  form  of  sub- 

1  Huxley,  Animal  Automatism,  quoted  in  part  by  James,  The  Principles  of 
Psychology,  vol.  i.  p.  131. 

2  W.  K.  Clifford,  Lectures  and  Essays,  Body  and  Mind,  pp.  262-3,  quoted  by 
James. 


358  THE  RELATION  OF  MIND  TO  BODY 

consciousness  which  coexists  with  the  motion  of  the  legs,  if  we 
want  to  talk  about  mental  facts.  .  .  .  When,  therefore,  we  ask, 
'What  is  the  physical  link  between  the  ingoing  message  from 
chilled  skin  and  the  outgoing  message  which  moves  the  leg  ? '  and 
the  answer  is  '  A  man's  will,'  we  have  as  much  right  to  be  amused 
as  if  we  had  asked  our  friend  with  the  picture  what  pigment  he  had 
used  in  painting  the  cannon  in  the  foreground,  and  received  the 
answer,  '  wrought  iron.'  It  will  be  found  excellent  practice  in  the 
mental  operations  required  by  this  doctrine  to  imagine  a  train,  the 
fore  part  of  which  is  an  engine  and  three  carriages  linked  with 
iron  couplings,  and  the  hind  part  three  other  carriages  linked  with 
iron  couplings ;  the  bond  between  the  two  parts  being  made  up 
out  of  the  sentiments  of  amity  subsisting  between  the  stoker  and 
the  guard." 1 

596.  In  the  passages  quoted  both  authors,  professed  idealists 
however,  draw  a  common-sense  distinction  between  brain  and  mind 
on  the  ground  that  the  former  is  a  material  object,  whereas  the 
latter  is  not.     Huxley  thinks  it  impossible  that  mind  can  affect 
matter ;  but,  regarding  mind  as  a  '  product '  of  the  working  of  the 
brain,  believes  that  matter  can  affect  mind.     It  is  hard,  however,  to 
conceive  how  one  thing  can  directly  affect  another  without  being 
affected  back  again.     If  light  reaches  an  object,  it  is  reflected  or 
absorbed  ;  if  the  sun  attracts  the  earth,  the  earth  attracts  the  sun  ; 
if  I  touch  a  stone,  the  stone  touches  me ;  if  my  arm  makes  a 
movement,  the  arm  suffers  change.     All  relations  are  mutual.     If 
it  be  true  that  brain  can  affect  mind,  then,  judging  by  all  analogy, 
it  should  be  true  also  that  mind  can  affect  brain. 

597.  Clifford  is  even  less  consistent.     He  supposes  that  mind 
and  matter  do  not  affect  one  another ;  but  his  mind  was  evidently 
aware  of,  was  affected  by,  guards,  stokers,  engines,  carriages,  and 
pictures,  which  he  describes  as  material  existences.     He  derides 
the   'crude   materialism    of  the   savage,'   but  the  materialism  of 
common  sense,  which   he  here    adopts,  is    every  whit   as   crude. 
He  declares  that  "all   the   evidence  that  we  have  goes  to  show 
that   .   .    .   the  physical  facts  go   along   by   themselves,  and  the 
mental   facts  go   along   by  themselves.     There   is   a   parallelism 
between  them,  but  there  is  no  interference  of  one  with  the  other." 
But  to  imagine  this  unrelated  but  exactly  coincident  working  is 
to  imagine  the   greatest   of  miracles.     Moreover,  the  hypothesis 
involves  the  corollary  that  mind  is  useless,  and  that  the  unfeeling, 
unthinking  brain  is  by  itself  responsible  for  all  the  more  wonderful 

1  Op.  cit.t  Right  and  Wrong,  pp.  328-9,  quoted  by  James. 


THE  AUTOMATON  HYPOTHESIS  359 

activities  of  the  higher  animals,  including  man.  To  the  student 
of  evolution,  who  realizes  the  extreme  parsimony  of  nature,  and  the 
universality  of  adaptation,  such  a  notion,  Huxley  notwithstanding, 
should  be  unbelievable.1 

598.  Common  sense  tells  me  that  there  is  at  this  moment  a  cup 
of  coffee  on  my  table,  which  I  see  and  smell,  because  I  have  material 
eyes  and  a  material  nose,  but  which  I  would  neither  see  nor  smell  if 
I  had  lost  the  eyes  and  nose.    I  become  conscious  of  a  desire  to  drink, 
and,  apparently  because  of  that  desire,  my  hand,  a  thing  as  material 
as  my  brain,  goes  out  and  seizes  the  cup.     I  drink  with  a  material 
body,  and  feel  a  satisfaction  which  is  mental.     My  entire  life  is 
filled  with  such  convincing  experiences,  and  so,  as  far  as  I  am  able 
to  judge,  is  the  life  of  every  one  else.     At  any  rate,  the  evidence  is 
such  that  every  human  being  over  the  age  of  a  few  weeks,  and  I 
think  every  conscious  animal  that  can  think  at  all,  is  convinced,  in 
effect,  that  mind  and  body  influence  one  another — that,  for  example, 
he  can  move  his  body  at  will,  and  that  when  his  body  is  injured  he 
suffers  pain  as  a  consequence.     The  whole  of  our  private  and  public 
conduct,  the  entire  structure  of  the  family  and  of  society,  is  founded 
on  this  belief  that  mental  and  bodily  actions  are  not  links  in  separate 
chains  of  events,  but  links  in  the  same  chain.     Thus  we  bestow 
material  gifts,  seek  to  please  those  we  love,  and  imprison  and  even 
hang  men  who  have  consciously  broken  the  law — whose  minds,  as 
we  suppose,  have  influenced  their  bodies.     But  we  do  not  punish  or 
even  blame  a  man  when  he  unconsciously  develops  a  cancer  which 
offends  sight  and  smell,  or  an  infectious   disease  which   starts   a 
destructive  epidemic.     Continually,  therefore,  we  blame  the  mind 
for  the  doings  of  the  body,  and  punish  the  body  for  the  doings  of 
the  mind. 

599.  In  fact,  given  the  existence  of  the  body,  then,  as  far  as  the 
evidence  goes,  there  is  nothing  in  the  whole  range  of  experience  so 
certain  apparently  as  that  mind  and  body  affect  one  another.     It 
is  not  the  lack  of  evidence  that  is  the  obstacle  to  belief,  but  the 
difficulty  of  conceiving  \uzvr  a  material  thing  can  affect  an  immaterial 
thing,  and  vice  versa.     But  matter  itself  is  inconceivable.     Having 
swallowed   the   camel,  we   have   no   right  to    put   on  .an   air   of 
delicate  discrimination  and  strain  at  the  gnat.     When  evidence  is 
massive  and  apparently  conclusive — as  it  is  in  this  case,  if  any- 
where— the  probabilities  are  that  the  apparent  inconceivability  of 
a  thing  is  due,  not  to  its  non-existence,  but  to  our  mental  limita- 
tions— to  our  ignorance,  lack  of  the  right  perceptive  powers,  and 

1  See  James,  Principles  of  Psychology,  vol.  i.  pp.  138-144. 


360  THE  RELATION  OF  MIND  TO  BODY 

the  like.  We  have  no  senses  by  which  we  can  perceive  minds ; 
therefore  we  are  unable  to  conceive  how  they  affect  or  are  affected 
by  brains ;  but  that  does  not  confer  on  us  the  right  to  declare 
dogmatically  that  there  is  no  relation  save  a  parallelism.  Other 
existences,  though  equally  inconceivable,  are  readily  believed  in 
by  all  of  us,  including  Huxley  and  Clifford,  merely  because  suffi- 
cient evidence  demonstrates  their  existence.  Thus  both  authors 
accepted  the  theory  of  gravitation  as  a  true  statement  of  fact ; 
that  is,  they  supposed  that  the  earth  attracts  bodies  to  its  surface 
by  means  of  an  immaterial  something,  which,  acting  across  millions 
of  miles  of  space,  affects  even  the  sun  and  the  stars.  "  One  cannot 
thus  blow  hot  and  cold.  One  must  be  impartially  naifm  impartially 
critical." l 

600.  For  the  idealist,  material  bodies  (e.g.  brains)  do  not  exist. 
His  insurmountable  difficulty  is  to  account  for  the  coexistences  and 
sequences  of  phenomena.2  It  is,  for  example,  no  easier  for  him  to 
imagine  that  iron  (a  mere  appearance)  can  couple  railway  carnages 
(also  mere  appearances)  than  to  imagine  that  feelings  of  amity  can 
perform  the  task.  To  adult  people,  thinking  in  common-sense 
terms,  the  idea  that  immaterial  minds  can  influence  material  brains 
seems,  on  the  face  of  it,  very  absurd — as  absurd  as  that  sentiments 
of  amity  can  couple  railway  carriages.  On  the  other  hand,  the 
notion  that  the  chains  of  physical  and  mental  facts  are  distinct  and 
separate  seems  reasonable — as  reasonable  as  that  feelings  cannot 
connect  railway  carriages.  But  why  does  the  one  seem  absurd  and 
the  other  reasonable  ?  Only,  I  think,  because  experience  has  im- 
pressed on  us,  till  we  accept  its  teaching  as  a  natural  law,  that, 
while  sentiments  do  not  directly  influence  such  things  as  railway 
carriages,  physical  things  do.  An  infant  would  feel  no  sense  of 
absurdity  in  the  one  case  or  of  reasonableness  in  the  other ;  nor 
should  we  had  our  experience  been  different.  We  consider  things 
reasonable  or  absurd  accordingly  as  they  do,  or  do  not  accord  with 
previous  experience.  Our  experience  is  that  sentiments  do  not 
influence  such  things  as  railway  carriages,  with  which  they  have  no 
direct  connexion.  Therefore,  though  the  evidence  that  brains  and 
sentiments  are  directly  connected,  and  that  they  influence  one 
another  is  immensely  massive,  we,  or  at  least  some  of  us,  reasoning 
from  analogy,  tend  to  suppose  that  neither  connexion  nor  influence 
exist.  It  would  be  quite  as  reasonable  to  suppose  that  there  is  no 
such  thing  as  gravitation  or  magnetism. 

1  James,  Principles  of  Psychology,  vol.  i.  p.  137. 
8  See  §  566  (footnote  2). 


THE  AUTOMATON  HYPOTHESIS  361 

601.  Like  Huxley  and  Clifford,  many  modern  writers  insist  on 
"  these  two  notions,  of  the  absolute  separateness  of  mind  and  matter, 
and  of  the  invariable  concomitance  of  a  mental  change  with  a 
bodily  change." l  "  But  this  '  concomitance '  in  the  midst  of '  absolute 
separateness '  is  an  utterly  irrational  idea.  It  is,  to  my  mind,  quite 
inconceivable  that  consciousness  should  have  nothing  to  do  with  a 
business  that  it  so  faithfully  attends."2  ...  "To  comprehend 
completely  the  consequences  of  the  dogma  so  confidently  enunciated, 
one  should  unflinchingly  apply  it  to  the  most  complicated 
examples.  The  movements  of  our  tongues  and  pens,  the  flashings 
of  our  eyes  in  conversation,  are  of  course  events  of  a  material  order, 
and  as  such  their  antecedents  must  be  exclusively  material.  If  we 
knew  thoroughly  the  nervous  system  of  Shakespeare,  and  as 
thoroughly  all  his  environing  conditions,  we  should  be  able  to  show 
why  at  a  certain  period  of  his  life  his  hand  came  to  trace  on  certain 
sheets  of  paper  those  crabbed  little  black  marks  which  we  for  short- 
ness' sake  call  the  manuscript  of  Hamlet.  We  should  understand 
the  rationale  of  every  erasure  and  alteration  therein,  and  we  should 
understand  all  this  without  in  the  slightest  degree  acknowledging 
the  existence  of  the  thoughts  in  Shakespeare's  mind.  The  words 
and  sentences  would  be  taken,  not  as  signs  of  anything  beyond 
themselves,  but  as  little  outward  facts,  pure  and  simple.  In  like 
manner  we  might  exhaustively  write  the  biography  of  those  two 
hundred  pounds,  more  or  less,  of  warmish  albuminoid  matter  called 
Martin  Luther,  without  ever  implying  that  it  felt. 

"  But,  on  the  other  hand,  nothing  in  all  this  could  prevent  us 
from  giving  an  equally  complete  account  of  either  Luther's  or 
Shakespeare's  spiritual  history,  an  account  in  which  every  gleam 
of  thought  and  emotion  should  find  its  place.  The  mind-history 
would  run  along  the  side  of  the  body-history  of  each  man,  and 
each  point  in  the  one  would  correspond  to,  but  not  react  upon,  a 
point  in  the  other.  So  the  melody  floats  from  the  harp-string,  but 
neither  checks  nor  quickens  its  vibrations  ;  so  the  shadow  runs 
alongside  the  pedestrian,  but  in  no  way  influences  his  steps."  3 

"  My  conclusion  is  that  to  urge  the  automaton  theory  upon  us, 
as  it  is  now  urged,  on  purely  a  priori  and  ^^-metaphysical 
grounds,  is  an  unwarrantable  impertinence  in  the  present  state  of 
psychology."  4 

1  Chas.  Mercier,  The  Nervous  System  and  the  Mind,  p.  1 1 . 

2  James,  Principles  of  Psychology,  vol.  i.  p.  136. 

3  James,  Principles  of  Psychology,  vol.  i.  pp.  132-3. 
*Op.  «'/.,  vol.  i.  p.  138. 


362  THE  RELATION  OF  MIND  TO  BODY 

602.  Assuming,  then,  that  brain  and  mind  influence  one  another, 
what  is  the  connexion  between  the  two  ?     It  has  been  said  very 
crudely,  but  I  think  with  some  element  of  truth,  that  the  brain 
secretes  thought  as  the  liver  secretes  bile.     It  has  been  said  equally 
crudely  that  the  mind,  like  heat  and  electricity,  is  a  form  of  motion. 
It  has  been  said  that  mind  and  body  are  different  aspects  of  the 
same  thing,  a  statement  which  is  merely  verbal  in  the  sense  that  it 
conveys   no  intelligible  idea.     It  has  been  said  that  mind  and  body 
are  distinct  but  temporarily  related  things,  and  that  mind  bears  the 
same  relation  to  body  as  the  musician  to  his  instrument ;  in  which 
case  the  actions  of  the  body  are  comparable  to  the  music.     It  has 
been    thought   that  mind   is  the  music  that   proceeds   from   the 
instrument,  the  body,  and  that  the  environment  is  the  musician, 
the  thing  that  stimulates  the  body,  the  brain,  to  produce  the  music. 
This  is  the  common-sense,  and,  I  think,  the  correct,  notion.     But 
it  is  a  notion  which  is  capable  of  expansion. 

603.  To  me,  bearing  in  mind  the  theory  of  evolution,  it  seems 
probable  that  thinking  and  feeling  are  forms  of  doing,  and  that  the 
brain  is  the  doer;    or,  in  other  words,  that  mind  is  one  of  the 
products  of  brain  activity,  one  of  the  functions  of  the  brain,  one 
of  the  things  that  it  does.     I  say  one  of  the  things,  for  not  only 
does  the  brain,  as  I  suppose,  think  and  feel,  but  it  receives  and 
despatches  stimuli.     I  do  not  know  how  brain  produces  mind  any 
more  than  I  know  how  one  material  body  attracts  another  across 
space.     But,  as  far  as  I  am  able  to  judge,  the  evidence  indicates 
that  mind  arises  only  when  there  is  an  expenditure  of  energy  in 
the  brain ; — when  there  is  no  brain  there  is,  apparently,  no  mind  ; 
when  a  portion  of  the  brain  is  destroyed  or  injured,  and  ceases  to 
function,  or  functions  imperfectly,  a  corresponding  portion  of  the 
mind  is  eliminated  or  is  imperfect ;  accordingly  as  the  brains  of  the 
higher  animals  are  complex  and  ample  so  are  their  minds  ;  mental 
exhaustion  bears  a  relation  to  physical  (brain)  exhaustion ;  and  so 
on.     I  assume,  therefore,  as   the  most  probable  conjecture,  that 
mind  is  somehow  a  consequence  of  the  work  of  the  brain.     When 
energy  is  expended  in  the  muscles  of  the  arm,  molecular  movements 
occur,  from  which  finally  result  the  muscular  contractions,  by  means 
of  which  the  arm  is  moved  and  the  hand  does  its  varied  work.     So, 
apparently,  when   energy   is   expended   under   conditions   which 
exist  in  certain  forms  of  nervous  tissue  (e.g.  brains),  mind  results, 
and  the  brain  does  its  varied  work.     But  when   I  think  of  the 
chain  of  events  that  end  in  the  movements  of  the  hand,  I  think 
from  first  to  last  of  nothing  but  matter  in  motion.     If  I  had  a 


MIND  AND  ENERGY  363 

sufficiently  powerful  microscope,  I  should  be  able  to  perceive  the 
whole  chain,  and,  within  narrow  limits,  to  think  of  it  in  terms  of 
causation.  Even  now  my  perceptive  powers  are  such  that  they 
supply  me  with  materials  which  enable  me  to  imagine  it.  But  no 
microscope,  however  powerful,  could  enable  me  to  perceive  how 
the  molecular  movements  in  the  brain  result  in  mind.  Even  if  I 
could  see  the  movements  of  the  molecules  of  another  man's  brain, 
even  if  I  learned  that  certain  movements  in  certain  regions  of  his 
brain  always  coincided  with  certain  of  his  feelings  and  thoughts,  I 
should  yet  be  unable  to  perceive  the  link  between  the  two  trains 
of  happenings,  the  mental  and  the  physical.  And,  since  my 
perceptual  powers,  however  aided,  are  such  that  I  could  not 
perceive  the  link,  therefore  I  cannot  think  in  terms  of  it.1  Never- 
theless, this  is  not  the  main  difficulty.  It  is  merely  part  of  the 
larger  difficulty  raised  by  the  idealist — the  difficulty  of  conceiving 
how,  even  if  material  bodies  exist,  our  minds,  which  are  so 
profoundly  different  from  material  objects,  which  do  not  occupy 
space,  and  have  none  of  the  properties  by  means  of  which  material 
objects  act  and  react  on  one  another,  can  be  affected  by  such 
objects,  can  become  aware  of  them.  But,  if  we  accept  the  common- 
sense  view,  and  suppose  that  material  bodies  both  exist  and  affect 
our  minds,  then,  though  we  cannot  conceive  how  the  minds  are 
thus  affected,  it  seems  to  me  that  we  have  no  alternative  but  to 
suppose  that  our  minds  are  produced  by  our  brains.  As  far  as  we 
know,  our  minds  are  nothing  other  than  streams  of  feelings,  states 
of  consciousness.  Ex  hypothesi,  some  of  these  feelings  symbolize 
material  objects.  When  we  become  aware  of  an  object,  that 
object  causes — in  the  full  sense  of  the  word  causes — that  feeling  to 
arise.  But  its  action  on  the  mind  is  not  direct.  It  first  produces 
a  change  in  a  sense-organ.  This  change  produces  in  turn  a  change 
in  a  nerve,  and  that  again  a  change  in  the  brain.  Thereupon  we 
become  aware  of  the  object.  It  follows,  that  if  material  objects 
exist,  and  if  our  minds  are  aware  of  them,  then  our  brains  produce — 
in  the  full  meaning  of  the  word  produce — the  feelings  that  symbolize 
them.  And,  if  it  be  admitted  that  they  produce  these  items  in  the 
stream  of  feelings,  we  have  no  grounds  for  denying  that  they  pro- 
duce any  of  the  items,  even  the  highest  flights  of  thought. 

604.  When  we  know  the  conditions  exactly,  we  are  able  to 
measure  work  in  terms  of  the  energy  expended  ;  for  example,  we 
are  able  to  say  that  under  certain  conditions  a  certain  expenditure 
of  energy  will  raise  a  certain  mass  a  certain  distance.  We  are 

1  See  §573. 


364  THE  RELATION  OF  MIND  TO  BODY 

unable  to  measure  feeling  in  this  way — to  say  that  a  certain 
feeling  arises  in  relation  to  a  certain  part  of  the  brain  when  there 
is  a  certain  expenditure  of  energy  in  the  latter.  Consequently — 
merely  because  we  cannot  measure  feeling  in  this  way — it  has 
been  argued,  in  effect,  that  there  is  no  connexion  between  the 
two.  A  vast  amount  of  nonsense  has  been  written  on  this  basis. 
For  example,  we  are  told  that  the  thoughts  of  a  Shakespeare  and 
those  of  an  imbecile  bear  no  relation  to  the  amount  of  energy 
respectively  expended  by  them.  Here  the  excellence  of  the 
thinking,  as  excellence  is  estimated  by  us,  is  taken  as  a  criterion, 
and  it  is  assumed  that  the  greater  the  excellence  the  greater 
should  be  the  expenditure  of  energy.  The  assumption  is  obviously 
absurd — as  absurd  as  if  it  were  argued  that,  because  good  and  bad 
railway  engines  give  different  results,  therefore  the  expenditure  of 
coal  has  nothing  to  do  with  their  movements.  Moreover,  this 
hypothesis,  that  sensation  and  thought  and  the  concurrent 
expenditure  of  energy,  bear  no  proportion  to  one  another,  is 
contrary  to  the  universally  accepted  belief  that  every  mental 
change,  every  feeling,  is  correlated  with  a  brain  change ;  for  it  is 
not  denied  by  any  one  that  cerebral  changes,  like  other  physical 
events,  result  from,  and  are  proportionate  to,  the  expenditure.  It 
is  certain  that  feeling  is  unknown  to  us  except  in  connexion  with 
the  work  of  nervous  tissue.  But,  since  the  conditions  under  which 
the  expenditure  occurs  are  but  little  known,  we  cannot  estimate 
the  amount  of  it  in  terms  of  feeling ;  and,  apparently,  because  our 
perceptive  powers  are  limited^  we  are  unable  to  conceive  how  the 
working  of  the  brain  gives  origin  to  mind. 

605.  Of  course,  as  just  indicated,  mind  may  be  considered  as 
comparable,  not  to  the  music  that  proceeds  from  the  instrument, 
but  to  the  player  who  plays  on  it.  But  this  hypothesis  of  an 
independent  agent  seems,  at  least,  unnecessary.  We  shall  see 
immediately  that  there  is  convincing  evidence  that  mind  is  a 
product  of  evolution.  As  a  function  of  nervous  tissue,  we  can 
conceive  of  it  as  coming  gradually  into  being  under  the  influence 
of  natural  selection.  Or  rather,  we  can  conceive  the  brain  as 
evolving  and  becoming  capable  of  doing  more  and  more  varied  work, 
just  as  we  can  conceive  the  hand  as  so  evolving.  But,  if  we  think 
of  mind  as  an  independent  player  who  operates  on  the  brain,  and 
so  directs  the  activities  of  the  body  of  which  the  brain  is  a  part, 
how  shall  we  account  for  the  existence  of  this  player  ?  Is  there  a 
definite  amount  of  mind  in  the  universe  as  there  is  of  substance 
and  energy,  and  is  he  somehow  evolved  out  of  this  fund  ?  Is  a 


THE  EVOLUTION  OF  MIND  365 

certain  amount  of  mind  somehow  captured  and  attached  to  each 
brain,  human  and  brute  ?  Or  is  he  and  others  of  his  kind  miracu- 
lously created  out  of  nothing,  when  brains,  including  those  of  lower 
animals,  come  into  being  and  begin  to  function  ?  In  any  case  the 
player,  if  he  exists,  lies,  if  anything,  even  farther  outside  the  range 
of  observation  than  even  '  matter  in  itself.'  We  have  no  means  of 
knowing  anything  about  him.  All  we  know  quite  certainly  is  that 
there  is  mind,  and  the  mind  tells  us  that  it  is  associated  with  a 
brain,  and  with  expenditure  of  energy.  To  us  mind  is  a  function 
of  the  brain. 

606.  The  physical  characters  of  animals  develop  in  response  to 
stimuli,  in  directions  and  within  limits  that  have  been  closely  fixed 
by  evolution.  On  that  account  the  body  of  every  normal  man  is 
very  like  the  body  of  every  other  normal  individual  of  the  same 
variety.  Thus  the  lungs  and  brain  of  one  person  are  very  like  the 
lungs  and  brain  of  any  other.  We  attribute  these  likenesses  to  the 
fact  of  a  common  descent.  But,  in  spite  of  this  common  descent, 
the  mind  of  every  man  so  develops  as  to  be  immensely  different 
from  the  mind  of  every  other  man,  past  or  present.  For  example, 
while  my  father  acquired  a  knowledge  of  military  science,  my  mind 
has  grown  in  such  a  way  that  I  know — more  or  less  imperfectly — 
the  art  of  medicine.  My  neighbour,  the  sailor,  likes  and  dislikes 
one  lot  of  people ;  I  quite  another  lot.  He  is  familiar  with  one  set 
of  scenes  ;  I  with  quite  other  scenes.  If  we  suddenly  exchanged 
bodies  we  should  scarcely  be  conscious  of  the  change  till  the  mirror 
or  the  behaviour  of  other  people  revealed  it ;  if  we  exchanged 
minds  we  should  be  as  lunatics  in  one  another's  environments.  Had 
I  been  captured  as  an  infant  by  savages,  and  reared  by  them,  I 
should  now  resemble  my  educators  mentally  much  more  nearly 
than  my  progenitors.  For  example,  I  should  know  only  the 
things  that  they  know — the  scenes,  the  people,  the  aspirations. 
Obviously  then  intellectual  characters  cannot  have  been  evolved 
in  the  same  sense  as  physical  characters.  Thus,  a  knowledge  of 
medicine  can  never  have  been  evolved  in  my  case  in  the  same 
sense  that  brains  have  been  evolved.  How  then  does  it  happen 
that  I  possess  a  knowledge  of  medicine?  It  seems  to  me,  as  the 
only  probable  explanation,  that  mind  is  not  a  thing  distinct  from 
the  brain,  but  only  the  work  of  the  brain — just  as  manipulation  is 
the  work  of  the  hand.  Nature  has  not  directly  evolved  immaterial 
minds  any  more  than  she  has  evolved  manipulations.  She  has 
merely  evolved  brains  and  hands  capable  of  doing  work  useful  to 
the  individual.  The  kind  of  brain  she  has  evolved  in  the  human 


366  THE  RELATION  OF  MIND  TO  BODY 

species  is  particularly  capable,  within  limits  that  vary  with  indi- 
viduals, of  learning  to  do  infinitely  varied  and  complex  work,  with 
a  constantly  increasing  degree  of  facility  and  skill.  For  that  reason 
my  brain  has  done,  not  what  the  brains  of  my  predecessors  could 
not  do,  but  what  they  did  not  do  (e.g.  the  work  which  results  in 
the  knowledge  of  medicine).  I  believe,  then,  if  we  consider  these 
two  facts  together,  the  facts  that  human  brains  are  much  alike,  but 
human  minds  very  different ;  and  if,  moreover,  we  think  in  terms 
of  common  sense  and  accept  the  theory  of  evolution,  then  we  are 
forced  to  conclude  as  the  only  course  open  to  us,  that  mind  is  the 
work,  or  rather  part  of  the  work,  of  the  brain. 


CHAPTER   XX 
REFLEX  ACTION,  INSTINCT,  AND  REASON 

Mind  is  associated  with  nervous  tissue — It  is  adaptive — It  is  related  to  move- 
ment— The  evolution  of  mind — Reflex  and  voluntary  actions — Intelligence  and 
reason — Memory — Traditional  knowledge — The  mental  characteristics  of  ants — 
The  instincts  of  man  —  Sucking  —  Crying  —  Weariness — Hunger — Thirst — Imita- 
tiveness — Sexual  and  parental  love — The  mutation  theory — The  importance  of 
mental  acquirements. 


A; 


607.  ^  MASS  of  evidence  indicates  that  mind  is  especially 
associated  with  nervous  tissue.  In  fact,  there  is  no 
clear  evidence  that  consciousness,  even  in  the  form 
of  the  most  rudimentary  feeling,  is  anywhere  present  except  in 
conjunction  with  those  masses  of  nerve  cells  which  are  termed 
ganglia,  the  largest  of  which  is  the  brain.  Mind  appears  to  be 
rudimentary,  or  even  non-existent  in  animals  in  which  ganglia 
are  relatively  little  developed  or  absent.  It  is  found  in  greater 
amplitude  in  the  higher  animals  in  which  the  ganglia  are  better 
developed.  In  the  highest  animals  it  appears  associated  exclusively 
with  the  brain.  Moreover,  mind  seems  invariably  associated,  not 
only  with  ganglia,  but  also  with  sense  organs — eyes,  ears,  tactile, 
and  taste  organs,  and  the  like — which  are  mostly  situated  at,  or 
near,  the  surface  of  the  body,  and  which  receive  from  the  external 
world  and  transmit  to  the  ganglia  messages  (stimuli)  derived  from 
light,  sound,  contact,  and  the  like — messages  which  in  some  way 
awaken  an  activity  which  is  correlated  to  consciousness. 

608.  Mind  is  useful  to  the  animal  that  possesses  it  only  in  so 
far  as  it  controls  his  actions  by  initiating,  guiding,  or  inhibiting 
them.  If  the  animal  is  of  a  relatively  simple  type,  living  in  a  com- 
paratively simple  environment,  his  equipment  of  nervous  tissue 
and  mind  is  correspondingly  simple.  If,  on  the  other  hand,  he 
is  fitted  for  more  complex  surroundings,  and  if,  therefore,  his 
activities  must  be  adapted  to  meet  a  number  of  more  or  less 
remote  contingencies,  to  achieve  more  or  less  far  off  aims,  his  brain 
and  mind  display  a  corresponding  complexity.  Compare,  for 
example,  a  sea-anemone,  whose  consciously  directed  movements, 

367 


368         REFLEX  ACTION,  INSTINCT,  AND  REASON 

if  any  such  occur  in  him,  are  adapted  only  to  meet  the  needs  of 
the  moment,  with  a  man,  who,  in  early  youth,  may  form  a  plan 
(e.g.  the  achievement  of  wealth),  and  pursue  it  undeviatingly  in 
ways  remote  from  the  end  during  all  the  varied  scenes  of  a  long 
life. 

609.  Since  mind  is  clearly  adaptive,  and  since  it  increases  in 
amplitude  and  complexity  from  the  lower  to  the  higher  animals, 
it  is  apparently  as  much  a  product  of  evolution  as  the  function  of 
any  physical  organ,  for  example  the  hand.     Certainly,  we  have 
as  much  reason  to  suppose  it  is  such  a  product — to  suppose  that  the 
functions  of  the  brain  have  undergone  evolution  in  the  same  sense,  in 
the  same  way,  and  by  the  same  means  as  the  functions  of  the  hand. 
It  is,  in  fact,  a  'character'  (a  reaction  to  stimulus)  of  the  indivi- 
dual, which,  as  far  as  we  are  able  to  surmise,  was,  like  other  useful 
characters,  absent  in  remote  ancestors,  had  its  origin  in  variations, 
and,  passing  through  simple  to  more  complex  types,  underwent 
evolution    (as  a  function)   by    the   action   of  Natural    Selection. 
There  is  evidence  that  we  are  able  by  careful  selection  to  increase 
or   decrease   in    any   desired    direction    the   intelligence    of    our 
domesticated  animals.     In  parasites  and  other  animals  which  have 
forsaken   an    active  existence,  mind  appears  to  have  undergone 
retrogression  through  cessation  of  selection.     Again,  some  animals, 
which   lead  an  active  existence  early  in  the  individual  life,  but 
which  lapse  into  an  inactive  adult  stage,  seem  to  lose  their  minds 
just  as  they  lose  their  larval   organs.     In  brief,   mind  owes  its 
existence  to  its  utility. 

610.  Various  authors  have  supposed  that,  "  the  beginnings  of 
mental  life  date  back  from  the  beginnings  of  physical  life.     The 
question  of  the  origin  of  mental  development  thus  resolves  itself 
into  the  question  of  the  origin  of  life."  *     If  they  are  right  we  are 

1Wundt,  Principles  of  Physiological  Psychology,  Eng.  Trans.,  vol.  i.  p.  31. 
Here  Wundt  is  very  unconvincing.  We  are  told  that  "  the  beginnings  of  a 
differentiation  of  mental  function  can,  however,  be  found  even  in  the  protozoa. 
.  .  .  The  only  sense  that  is  plainly  functioning  is  the  sense  of  touch  .  .  .  the 
cilia  with  which  these  infusorians'are  furnished  .  .  .  are  .  .  .  organs  of  motion. 
They  function  as  organs  of  touch,  and  sometimes  appear  sensitive  to  light  as 
well  "  (pp.  33-4).  But  reaction  to  stimulus  does  not  necessarily  imply  sensation. 
The  environment  of  infusorians  is  so  simple,  their  reactions  to  it  so  few,  that 
sensation  superimposed  on  the  reactions  made  by  them  would  appear  to  be  a 
useless  epi-phenomenon.  No  sensations,  as  far  as  we  are  aware,  accompany 
much  more  complex  reactions  in  our  own  bodies,  for  example  the  normal  move- 
ments of  our  intestines.  "  In  the  compound  organisms  we  observe  a  more 
radical  differentiation  of  mental  function  and  its  bodily  substrate.  The  cell- 
mass  of  the  yolk,  originally  homogeneous,  divides  first  of  all  into  a  peripheral  and 
a  central  layer  of  different  structural  character,  while  the  cleavage  cavity  gradually 


THE  ALLEGED  UNIVERSALITY  OF  MIND         369 

guilty  of  great  cruelty  when  we  boil  our  vegetables  alive.  Other 
writers,  influenced  by  the  uniqueness  of  mind,  attribute  some  sort 
of  mentality  even  to  lifeless  objects.  Judged,  however,  from  the 
standpoint  of  evolution,  there  does  not  appear  to  be  any  warrant 
for  these  fanciful  speculations.  As  we  shall  see,  the  function  of 
mind  is  adaptation.  It  is  difficult  to  believe  that  a  thing  so 
clearly  useful,  so  evidently  bearing  the  marks  of  evolution,  can 
have  existed  prior  to  its  usefulness.  If  there  was  any  unique 

widens  out  to  form  the  future  body  cavity.  At  this  stage  sensation  and  move- 
ment appear  to  reside  exclusively  in  the  outer  cell-layer,  the  ectoderm,  while 
the  nutritive  functions  are  discharged  by  the  inner  layer  or  entoderm."  Here, 
then,  according  to  Wundt  is  a  phenomenon  hitherto  non-existent  in  nature — 
i.e.,  living  cells  devoid  of  sensation  which  nevertheless  perform  perfectly  well 
their  complex  function  of  elaborating  nutriment  for  themselves  and  other  cells. 
Loss  of  sensation  is  attributed  to  evolution.  "  At  a  higher  level  of  evolution  a 
third  layer  of  cells,  the  mesoderm,  forms  between  the  two.  This  discrimination 
of  organs  is  accompanied  by  differentiation  of  the  elementary  constituents  of  the 
tissues.  When  the  separation  of  ectoderm  and  entoderm  is  first  accomplished 
the  cells  of  the  former  discharge  the  combined  functions  of  sensation  and  move- 
ment. The  initial  step  towards  the  separation  of  these  two  cardinal  functions  is 
apparently  taken  in  the  hydridae  and  medusae,  where  the  ectoderm  cells  send  out 
contractile  processes  into  the  interior  of  the  body.  The  sensory  and  motor 
functions  are  still  united  in  a  single  cell,  but  are  distributed  over  different  portions 
of  it.  In  the  next  stage  the  properties  of  sensation  and  contractibility  pass  to 
special  and  spatially  separated  cells  "  (p.  36).  At  this  stage,  then,  the  stage 
reached  by  the  higher  animals,  Wundt  supposes  that  sensation  has  departed  from 
the  contractile  cells.  Nevertheless  they  contract  on  receipt  of  stimulus  precisely 
as  they  did  before  its  departure.  But  the  only  evidence  of  sensation  they  ever 
afforded  was  contraction.  That  evidence  still  remains  and  is  as  inconclusive  in 
the  one  instance  as  in  the  other.  If  contact  alone  caused  an  infusorian  to 
contract  efficiently,  the  sense  of  touch  would  be  as  useless  to  it  as  to  a  muscle 
cell.  Before  we  attribute  sensation  to  such  low  animals  we  should  at  least  feel 
sure  that  this  wonderful  product  of  evolution  is  so  useful  to  them  as  to  be  an 
important  factor  in  securing  survival ;  that  is  we  should  feel  sure  that  touch  alone 
without  the  sense  of  touch  is  not  sufficient  for  their  needs.  The  functions  of  life, 
concentrated  in  a  single  cell  in  the  case  of  the  unicellular  organism,  are  distributed 
amongst  skin,  nerve,  muscle,  and  other  cells  of  higher  types.  But  this  separation 
of  function  does  not  involve  the  corollary  that  no  new  functions  (e.g.  sensation) 
have  been  evolved.  Touch  is  a  discriminating  agency  ;  but  discrimination  does 
not  necessarily  imply  a  mental  element.  Thus,  apparently  unaided  by  sensation, 
gland  cells  discriminate  between  the  substances  conveyed  to  them  by  the  blood. 
It  follows  that  an  infusorian  may  well  display  tactual  discrimination  and  yet 
feel  no  sensation.  Besides  infusorians,  many  cells  have  cilia.  In  multicellular 
organisms  "  all  the  cilia  of  adjoining  cells  do  not  move  at  once,  but  in  regular 
succession,  the  movement  travelling  from  one  cell  to  the  other,  but  how  this  co- 
ordination is  brought  about  we  do  not  know.  At  least,  it  is  independent  of  the 
nervous  system,  as  ciliary  movement  goes  on  in  isolated  cells  (i.e.  cells  that  have 
been  scraped  away)  and  in  men  it  has  been  observed  two  days  after  death." 
(Landois  and  Stirling's  Physiology,  vol.  ii.,  p.  613).  Here  the  cell,  which  is 
admittedly  devoid  of  sensation  and  is  cut  off  from  nerve  stimuli,  behaves  exactly 
like  an  infusorian  which  has  been  stimulated  by  touch. 
24 


370        REFLEX  ACTION,  INSTINCT,  AND  REASON 

thing  in  nature  out  of  which  it  was  evolved,  a  thing  outside  the 
range  of  our  perceptive  powers,  then  that  thing  was  not  mind  in 
any  real  sense  any  more  than  nitrogen  and  other  chemical 
elements  are  muscle. 

6 1 1.  Granting  that  mind  is   a   product  of  evolution,   that   it 
originated  in  connection  with  movement,  and  that  it  occurs  only 
in  connection  with  nervous  tissue,  to  me  it  seems  probable  that 
the  order  of  evolution  was  as    follows.     First,   through  Natural 
Selection,  cells,  the  function  of  which  was  contraction  and  without 
which  movement  would  have  been  impossible,  appeared  in  multi- 
cellular  organisms.     Many  unicellular  organisms  are  contractile, 
and  some  have  contractile  flagella.     Doubtless  the  contractility 
of  the  cells  of  the  higher  types  was  derived  from  [them.     Next, 
as  animals  became  larger  and  more  complex,  as  other  cells  under- 
went  differentiation,    as    the   masses    of    the    cells   which    were 
contractile  increased  in  size,  number,  and  complexity,  a  nervous 
system  was  evolved,  which  consisted  of  lines  of  communication 
(nerve   fibrils)   and   one  or  more  central  ganglia.      The  ganglia 
received  stimuli   through  the  '  afferent '  fibrils   from  the  surface, 
and  translated  them  into  other  stimuli  which  passed  outwards 
through  the  '  efferent '  fibrils  and  awakened  the  activities  of  various 
other  cells,  especially  the  contractile  cells.     The  function,  therefore, 
of  nervous  cells  was  to  co-ordinate  the  reactions  of  the  organism 
and  so  adapt  it  to  the  environment.     Next  there  were  evolved  on 
the  surface,  at  the  ends  of  the  nerve  fibrils,  organs  which  delicately 
discriminated   between    different   classes   of  stimuli — light,   heat, 
contact  with  foreign  bodies,  and  the  like.     Nerve  currents,  passing 
from  these  surface  organs,  were  transmuted  in  the  ganglia  into 
appropriate  stimuli  for  the  several  masses  of  contractile  and  other 
cells.     As  yet  there  was  no  consciousness. 

612.  Next,  the  surface  organs  which  received  stimuli  from  the 
environment  evolved  into  sense  organs,  where  originated  nerve 
currents  that  gave  origin  in  the  ganglia  to  sensations — delicately 
discriminating  stimuli  which  indirectly  (through  the  efferent  nerve 
currents  to  which  they  gave  rise)   exploded  the  right  stores  of 
energy  latent  in  this  or  that  mass  of  contractile  cells.     Throughout 
the  process  was  one  of  increasing  adaptation  to  the  environment. 
Thus  mind  dawned.     It  will  be  noted  that  here  I  attempt  nothing 
more  than    a   description    of  the   conditions   under   which,   as    I 
suppose,  mind  appeared.     I  indicate  when,  not  how,  it  appeared. 
I  do  not  know  how  nervous  tissue  does  this  work.     I  only  suppose 
that  it  was  rendered  possible  to  nervous  tissue  through  the  selection 


REFLEX  ACTIONS  371 

of  favourable  variations.  Lastly,  through  the  continued  action  of 
Natural  Selection,  sensations  took  on  those  peculiar  tones  which 
we  designate  as  pleasure  and  pain.  Thereupon  desire  and  will 
came  into  being.  The  animal  was  now  no  longer  an  automaton 
in  the  ordinary  sense  of  the  word.  It  felt,  and  in  a  real  sense 
desired  ;  and  some  of  its  activities  were  under  the  control  of  its 
desires,  or  rather  of  the  will  which  the  desires  awakened.  The 
whole  process,  I  suppose,  involved  a  very  gradual  co-ordinated 
change  in  which  other  cells  besides  nerve  cells  participated. 
There  was  no  mutation,  no  sudden  appearance  of  nervous  tissue 
or  of  mind  ;  for  such  a  sudden  development  could  have  been  useful 
only  if  it  had  involved  simultaneous  changes  in  several  classes 
of  cells — changes  so  numerous,  complex,  and  adaptive,  that  their 
simultaneous  occurrence  would  have  been  altogether  miraculous. 

613.  All  the  movements  of  living  beings,  which  result   from 
their  vital   activities  but  are  not  under  nervous  control,  may  be 
termed  '  protoplasmic.'     The  movements  of  plants  and  unicellular 
animals  and  ciliary  movements  are  examples.     Movements  made 
under  nervous  control  are  either  reflex  or  voluntary.     All  move- 
ments  under   nervous    control,    but   with    which    no    feeling    is 
associated,  are  reflex.     There   are  many  such  in  our  bodies,  for 
example  the  normal  movements  of  our  heart  and  intestines.     But 
some  movements,  which  are  rightly  termed  reflex,  have  a  great 
deal  of  feeling   associated   with   them.     Sneezing   and  the   con- 
vulsions resulting  from  tickling  are  examples.     Here,  not  only  does 
feeling  accompany  the  action,  but  it  initiates  it.     Neither  sneezing 
nor  the  convulsions  of  tickling  occur  in  the  absence  of  feeling  ;  for 
example,  in  people  under  the  influence  of  chloroform.     If  I  cough 
because  I  choose,  the  action  is  voluntary ;  if  I  cough  because  I 
must — because  an  irritation  in  the  larynx  compels  me  to  cough — 
the  action  is  involuntary.     But  often  I  can  control  the  reflex,  and 
delay,  and  in  some  cases  even  prevent  it.     A  reflex  action,  there- 
fore, is  not  necessarily  one  which  is  not  associated  with  sensation,  nor 
one  which  is   not  initiated  by  sensation,   nor   one   which   is   not 
controllable  by  the  will.     It  is  one  which  is  under  nervous  control 
but  which  is  not  directly  INITIATED  by  the  will.     This  definition 
is  unlike  those  commonly  accepted,  but  I  think  it  can  be  justified. 

614.  The  same  action  may  be  voluntary  at  one  time  and  reflex 
at  another.     If  the  reader  will  think  of  all  the  reflexes  he  can  call 
to  mind,  he  will  find  that  their  distinguishing  peculiarity  is  that 
they  cannot  be  set  agoing  by  the  direct  impulse  of  the  will.     Thus 
no  matter  how  strong  his  willing  he  cannot  really  sneeze  when  he 


372        REFLEX  ACTION,  INSTINCT,  AND  REASON 

wishes.  It  is  true  he  may  set  himself  sneezing  by  voluntarily  intro- 
ducing an  irritant  into  his  nose ;  but  the  irritant,  not  the  will,  is 
the  direct  cause  of  the  act.  So  also  he  is  able  to  make  himself 
sick  by  tickling  the  back  of  his  throat,  but  he  cannot  vomit  by  a 
pure  act  of  will.  Swallowing  is  another  example,  and  a  very  good 
one.  The  act  of  swallowing  seems  at  first  strictly  voluntary. 
Really  it  is  purely  reflex.  We  are  able  to  swallow  only  when 
we  have  something  to  swallow ;  that  is,  only  when  the  mechanical 
stimulus  which  starts  the  reflex  is  present  at  the  back  of  the  throat. 
The  reader  can  easily  test  this  by  swallowing  his  saliva  and  then 
trying  to  repeat  the  act.  He  will  succeed  only  after  he  has 
collected  more  saliva — supplied  more  mechanical  stimulus. 

615.  The  reflexes  are  all  'inborn  and  transmissible,'  that  is 
they  all  develop  in  the  individual  under  the  stimulus  of  nutriment, 
and  reappear  in  all  normal  offspring.  With  rare  exceptions,  they 
are  extremely  useful  to  him,  indeed  essential  to  his  survival.  For 
example,  no  child  lives  who  does  not  inherit  the  cardiac  and 
intestinal  reflexes  which  were  possessed  by  his  ancestors.  The 
exceptions  are  one  or  two  reflexes  which  seem  to  be  mere  by- 
products of  evolution — traits  correlated  to  more  useful  traits.  The 
convulsions  of  tickling  are  examples.  When  feeling  is  associated 
with  the  adaptive  reflexes  it  always  contributes  to  their  usefulness. 
In  some  cases  (e.g.  the  feeling  caused  by  food  in  the  larynx,  which 
in  turn  causes  swallowing)  feeling  is  the  discriminating  spark  which 
awakens  the  reflex.  In  other  cases,  by  promise  of  pleasure  or 
relief  from  pain,  it  awakens  desire,  which,  as  in  the  case  of  hunger, 
awakens  the  will  to  perform  those  voluntary  actions  which 
necessarily  precede  and  supply  the  stimulus  for  the  reflex  act  In 
some  instances,  as  in  the  case  of  the  reflexes  of  the  bladder  and 
lower  bowel,  the  will  acts  usefully,  not  because,  as  in  the  case  of 
swallowing,  it  initiates  the  performance  of  voluntary  actions  which 
in  turn  supply  stimuli  for  reflexes,  but  because  for  a  longer  or 
shorter  time  it  controls  or  inhibits  the  reflexes — because  it  is  able 
to  delay  their  performance  till  a  more  convenient  time.  Such 
reflexes  are  always  initiated  by  a  feeling  which  tends  to  awaken, 
not  only  the  reflex,  but  also  the  will  that  inhibits  it.  The  duration 
and  amount  of  the  control  which  the  will  is  capable  of  exercising 
is  always  proportionate  to  its  usefulness.  Thus  it  is  short  and 
slight  in  the  case  of  sneezing — as  a  rule  no  longer  than  gives  time 
to  swallow  food  already  in  the  mouth.  It  is  a  little  longer  in  the 
case  of  breathing.  In  the  case  of  coughing  it  is  short  in  proportion 
to  the  severity  of  the  irritation.  On  the  other  hand  the  control  is 


VOLUNTARY  ACTIONS  373 

more  persistent  and  more  perfect  in  the  case  of  bladder  and  bowel. 
But  always  the  reflex  impulse  tends  to  grow  stronger,  till  at  last 
it  overpowers  the  will.  No  adaptive  reflex  which  is  not  associated 
with  feeling  (usually  pleasure  or  pain)  is  under  the  control  of  the 
will.  Thus  we  cannot  voluntarily  control  the  beatings  of  our 
hearts  nor  the  movements  of  the  middle  portions  of  our  alimentary 
canals.  All  adaptive  reflexes  which  are  normally  associated  with 
feeling  are  directly  or  indirectly  under  the  control  of  will.  Thus, 
as  we  see,  the  bladder  reflex  which  promises  relief  from  pain  is 
directly  controlled  by  the  will,  whereas  the  swallowing  reflex 
which  promises  pleasure  is  indirectly  controlled  by  it,  for  the  will 
provides  those  voluntary  actions,  the  provision  of  food,  the  chew- 
ing and  removing  of  it  to  the  pharynx,  which  in  turn  awaken  the 
reflex  impulse  to  swallow. 

6 1 6.  We  see  then  how  clearly  the  reflexes  are  adaptive,  how 
plainly  they  bear  the  marks  of  .evolution.     On  the  other  hand,  we 
see  how  complex  they  are  both  physically  and  mentally ;  and  yet 
how  perfectly  they  link  up  with  the  rest  of  the  physical  and  mental 
activities  of  the   individual.     Every   complex   animal   has   these 
wonderful  reflexes.     Except  through  actual  miracle  such  manifold 
co-ordinated  activities  could  not  have  arisen  by  mutation.     Unless, 
therefore,  we  attribute  them  directly  to  a  supernatural  origin,  we 
must  assume  that  they  arose  gradually  by  the  continual  selection 
of  fluctuating  variations — by  a  process  which  gradually  and  con- 
currently  altered    the  whole  organism.      Here   also   we   have  an 
example,  emphasised  as  we  shall  see  by  the  whole  study  of  mind, 
of  facts  which  are  familiar  to  everyone,  which  nevertheless  since 
their   relations   are   complex   and    difficult    to   trace,   cannot   be 
classified  except  after  careful  thought.     '  Obvious  inferences/  such 
as  are  all  that  are  needed  in  anatomy  and  that  kind  of  botany  and 
zoology  which  takes  no  account  of  the  sequences  of  events  in  the 
evolution  of  the  race,  here  lead,  and  have  repeatedly  led,  only  to 
confusion  and  error. 

617.  Voluntary  acts  are  either  instinctive  or  (in  the  lack  of  a 
better  term)  rational.     As  far  as  I  am  aware,  no  one  but  myself 
regards  instinctive  actions  as  voluntary.     Usually  they  are  classed 
as  a  kind  of  reflex.     However,   I   feel  confident  I  am  right.     A 
voluntary  act  is  one  which  is  prompted  by  the  will.     If  we  think 
carefully  we  find   that  the  will,  in  turn,  is  always  prompted  by 
desire;  and  that  desire  again  is  always  prompted  by  present  or 
prospective  pleasure  or  pain.     The  desire  may  be  so  faint  that  we 
can  hardly  detect  it ;  but  unless  it  is  present  we  do  not,  we  cannot, 


374        REFLEX  ACTION,  INSTINCT,  AND  REASON 

act  voluntarily.  It  may  be  so  strong  as  to  be  irresistible,  in  which 
case  it  enlists  a  corresponding  strength  of  will.  Desire  cannot  be 
awakened  except  by  present  or  prospective  pleasure  or  pain — 
not  necessarily  '  physical '  pleasure  or  pain,  but  pleasure  or  pain  of 
some  sort — for  example  a  whimsical  pleasure  in  demonstrating 
that  we  are  able  to  disregard  '  physical '  pain,  in  which  case  the 
desire  to  achieve  the  pleasure  transcends  the  desire  to  avoid  the 
pain. 

6 1 8.  An  instinct  may  be  defined  as  an  '  innate  and  inherited '  mental 
impulse  or  inclination  to  do  a  certain  definite  act,  the  instinctive  act, 
on  receipt  of  a  certain  definite  stimulus.     Therefore  it  is  a  mental 
character  which  is  developed  in  the  individual  under  the  stimulus 
of  nutriment,  but  which  is  awakened  to  activity  by  experience  (the 
appropriate   stimulus).     For   example,  the   sexual  instinct  is  an 
'  innate '  character  that  is  aroused  by  the  presence  of  an  individual 
of  the   opposite   sex.     I    think   psychologists   believe    instinctive 
actions  to  be  types  of  reflex  action  only  because,  when  studying 
the   question,  they   have   limited  their   attention    mainly   to  the 
instincts  of  the  lower  animals.     We  have  then,  very  often,  no 
means  of  knowing  whether  any  given  action  is,  or  is  not,  prompted 
by  desire  and  directed  by  the  will.     But  when  we  consider  our 
own  instincts  we   are  on  safer  ground.     Our  knowledge  is  not 
then  derived  by  inference  from  the  actions  of  another  animal,  but 
from   actual   experience   of  the   mental  phenomena.     We   know 
our   own    instincts    therefore   with   an    intimacy   with   which   we 
cannot  know  those  of  the  lower  animals,  amongst  which  all  our 
own  instincts  have  their  counterparts.     Consequently  it  is  safer  to 
reason    from  our   instincts   to   those   of   lower   animals   than   to 
adopt  the  reverse  process.     Since  we  are  derived  from  lower  types, 
presumably,  our   instincts  are  of  the   same  nature.     They   may 
differ  in  degree,  they  can  hardly  differ  in  kind. 

619.  Consider,  then,  our  own  instincts,  for  example  the  instinct 
to  sleep  periodically,  to  rest  when  tired,  to  sport  when  rested,  to 
eat  and  drink  when  hungry  and  thirsty,  the  instincts  of  imitative- 
ness   and    curiosity,   and    the   deferred    instincts   of    sexual    and 
parental  love.     In  the  case  of  each  we  feel  strongly,  if  sometimes 
vaguely,  the  prompting  desire  to  seek  pleasure  or  to  avoid  pain 
which  is  the  actual  and  direct  stimulus  of  the  will  to  do,  which,  in 
turn   initiates   the   instinctive    act,   and    which   therefore   sharply 
differentiates  it  from  the  reflexes  which  are  never  directly  prompted 
by   the   desire   to   do   an    action.     Thus,   sleepiness   prompts   us, 
strongly  inclines  us,  voluntarily  to  assume  attitudes  of  repose,  as 


VOLUNTARY  ACTIONS  375 

also  does  weariness.  Clearly  it  is  the  presence  of  the  desire  that 
renders  the  act  voluntary.  Every  instinctive  impulse  is  nothing 
other  than  a  desire,  even  when  the  object  of  desire  is  not  easily  re- 
cognised. Were  the  desire  not  present  we  should  not  act.  Hunger 
inclines  us  to  procure  and  chew  our  food ;  both  actions  are  dis- 
tinctly voluntary.  Imitativeness,  curiosity,  sexual,  and  parental 
love,  also  prompt  us  to  acts  which  are  entirely  voluntary.  It  is 
true  that  sometimes,  when  the  prompting  desire  is  very  strong,  we 
are  colloquially  said  to  act  '  against  our  wills.'  As  a  fact,  however, 
except  in  the  case  of  the  reflexes,  we  never  do  act  against  them, 
though  we  often  act  against  our  judgments.  Wise  and  good 
actions  are  certainly  all  voluntary  ;  but,  equally  certainly,  not  all 
voluntary  actions  are  either  wise  or  good.  When  the  starving 
sailor  kills  and  eats  his  comrade  he  may  abhor  and  struggle  against 
his  desire.  Nevertheless  from  the  act  of  killing  to  the  act  of 
chewing  his  actions  are  voluntary.  He  performs  them  simply 
because  his  desire,  his  will  to  eat,  is  stronger  than  his  will  to 
abstain. 

620.  It  must  be  borne  in  mind  that,  especially  in  the  case  of 
beings  like  men  whose  desires  are  complex,  two  or  more  impulses 
inciting  to  different  actions  may  be  in  operation  at  the  same  time. 
When  one  is  distinctly  stronger  than  the  other,  we  yield  to  it  at 
once  ;  when  they  are  equally  balanced,  we  have  a  feeling  of  irre- 
solution.    Suppose  a  man  falls  in  love  with  his  friend's  wife,  the 
feeling  would  be  an  instinct,  and  would  impel  to  instinctive  acts. 
Opposed  to  it  might  be  a  desire  to  do  right.     He  will  certainly 
yield  to  the  stronger  desire,  and,  in  each  case,  his  action  will  be 
voluntary.     It  is  very  probable  that  before  taking  one  course  or 
the  other  he  will   seek   to   reinforce  his  desire   to   do   right   by 
picturing  all  the   consequences  of  doing  wrong.     But  if  he  acts 
wrongly  he  will  not   be  acting  against  all  his   desires,   but  only 
against  one  of  them  ;  not  against  his  whole  will,  but  only  against 
the  weaker  incitement  of  it.     No  one  is  held  blameworthy  for  his 
reflex  actions.     It  is  felt  that  he  does  not  initiate  them  by  his  will, 
and  that  even  when  he  is  able  to  some  extent   voluntarily  to 
control   them,    he    must    sooner   or   later   yield.      But    for   every 
kind  of  instinctive  act  he  may  be  held  blameworthy.     Therefore 
it  is  recognised   that  they  are   initiated   by   his   will.     On   that 
account  they  involve  questions  of  right  and  wrong,  meriting  praise 
or  blame. 

621.  Apart  from    his   reflexes,  what  man  ever   acted  except 
under   the    influence   of  desire?     The    anchorite    abstains    from 


376        REFLEX  ACTION,  INSTINCT,  AND  REASON 

pleasure  only  because  he  desires  and  anticipates  greater  pleasure 
in  heaven.  The  patriot  dies  because  his  desire  for  his  country's 
good  overmasters  his  desire  for  life.  The  tigress  that  has  captured 
prey  goes  hungry  because  her  instinctive  desire  for  food  is 
opposed  by  a  yet  stronger  desire  to  feed  her  cubs.  If  I 
deliberately  burn  myself,  it  is  only  because  my  desire  to  do  so 
is  stronger  than  my  desire  to  avoid  pain.  In  every  case  the 
action,  whether  instinctive  or  *  rational,'  is  prompted  by  desire, 
and,  if  prompted  by  desire  (which  awakens  the  will)  is  plainly 
voluntary,  plainly  different  from  those  distinctly  non-voluntary 
actions  which  we  term  reflex.  Compare,  for  example,  the  actions 
to  which  hunger  prompts  with  the  peristaltic  action  of  the  stomach 
when  hunger  is  satisfied.  The  former  are  instinctive,  the  latter  are 
reflex.  Wherein  lies  the  distinction  ?  Clearly  in  the  circumstance 
that  the  instinctive  actions  are  prompted  by  desire  and  initiated 
by  the  will,  whereas  the  reflex  actions  are  neither  prompted  by 
the  one  nor  initiated  by  the  other. 

622.  The  term  voluntary  is  sometimes  limited  to  deliberate  acts. 
Thus,  if  I  avoid  a  danger  by  taking  thought,  I  am  quite  rightly 
thought    to   act   voluntarily.     But,    if  I    impulsively   start  away 
from  it,  my  action  is  held  by  psychologists  to  be  involuntary  or 
even  '  reflex.'     But  we  shall  see  later  that  speed  and  absence  of 
deliberation  imply,  not  necessarily  lack  of  will,  but  only  a  quick 
and  smooth  working  of  it,  one  principal  condition   of  which   is 
absence  of  opposing  desires.     When  we  are  hungry  and  have  only 
one   dish,  we   set   to   work   without   hesitation.     If  half-a-dozen 
dishes  are  placed  before  us,  we  may  deliberate  before  setting  to. 
But   our    action  in  the  one  case  is  just  as  voluntary  as  in  the 
other.     Will  is  one  thing,  deliberation  is  quite  another  thing.     All 
deliberate  actions  are  certainly  voluntary  ;  but,  quite  certainly,  not 
all  voluntary  actions  are  deliberate.     When  we  are  beset  by  two 
or    more    nearly   evenly   balanced    desires,    we   hesitate,   reflect, 
deliberate.     But  these  mental  processes  are  quite   distinct  from 
will.     They  may  incline  the  scale  in  one  direction  or  the  other 
and   so   end    the   paralysis  of  will  which   results  from  balanced 
desires.     But  obviously  they  are  no  part  of  the  will,  nor  even  a 
necessary  accompaniment  of  it. 

623.  Voluntary    action    then   may   be   defined  as   action  which 
is  prompted  by  desire.     An  instinct,  we  see,  is  an  'innate'  and 
'  inherited '  inclination,  an  impulse,  to  act  in  a  certain  way  under 
certain   conditions.     At   a   fixed   stage   in   his   development   the 
caterpillar  builds  himself  a  cocoon.     His  dwelling  is  a  wonderful 


INTELLIGENT  ACTIONS  377 

structure,  but  from  our  human  point  of  view,  the  most  wonderful 
thing  is  that  he  does  not  learn  to  build  it.  He  may  never  have 
seen  a  cocoon  before,  and  he  constructs  only  one  in  his  life.  Yet 
his  work  is  perfect,  or  at  least  excellent,  and  it  is  as  good  at 
its  beginnings  as  at  its  endings.  Evidently  he  owes  nothing  to 
experience  beyond  the  stimulus  to  act,  but  is  impelled  and  guided 
throughout  by  that  '  innate  and  inherited '  faculty  which  we  term 
instinct.  Since  his  cocoon-building  instinct  does  not  appear  at 
the  beginning  of  conscious  life,  it  is  termed  a  deferred  instinct. 
He  has  many  such,  for  instance  the  instincts  of  flight  and  mating, 
which  do  not  appear  until  after  he  has  undergone  his  meta- 
morphosis into  a  butterfly. 

624.  On   the  other  hand,  man,  unlike  the  caterpillar,  cannot 
build  his  house  unless  he  first  learns  to  build  it.     He  depends,  not 
on    instinct,   but    on    stored   experience.     The   faculty   by   which 
experience  is  stored  in  the  mind  is  termed  memory.     The  faculty 
by  which  we  use  stored  experience  is  termed  intelligence.     When 
the  contents  of  memory  are  very  vast,  and  the  processes  of  thought 
by  which  they  are  utilised  comparatively  difficult  and  complex, 
intelligence  is  termed  reason.     INTELLIGENCE  and  REASON  depend, 
therefore,  on  MEMORY,  on  ability  to  learn,  on  capacity  to  profit  by 
stored  experience.     Memory  is  not  the  whole  of  intelligence,  but 
it  is  the  basis  of  it.     Without  memory,  there  could  be  sensation 
and  emotion,  but  no  thought  ;  for  the  materials  for  thought  would 
be  lacking.     Thinking  depends  on  such  processes  as  association, 
comparison,  discrimination,  inferring,  and  the  like,  which  in  turn 
depend  on  memory. 

625.  In  a  sense,  the  caterpillar  has  discrimination;  thus,  he 
can  distinguish  his  food  or  his  mate  from  other  objects ;  but  he 
has  not  the  kind  of  discrimination  which  is  so  much  used  by  man. 
His  discrimination  does  not  depend  on  a  comparison  of  present 
things  with  things  formerly  known  or  imagined,  but  merely  on 
differences  of  feeling  awakened    by  different   objects.     He   does 
that  which  he  feels  is  pleasant,  not  that  which  he  has  learnt  is 
pleasant.     If  a  man  had  no  memory  he  could  compare  no  two 
objects  or  ideas.     He  could  have  no  ideas.     He   could  perceive 
men   and  women  who  might  awaken  emotions  and  impulses  in 
him,  but  he  would  not  know  them  for  men  and  women,  nor  as 
big  or  small,  dark  or  fair,  near  or  far,  nor  would  he  know  the  ends 
of  the  actions   to  which   he  was  impelled.     Such   thoughts,  de- 
pending as  they  do   on  association   and   comparison,  could  not 
arise  in  his  mind,  which,  at  the  end  of  a  long  life,  since  he  had 


378         REFLEX  ACTION,  INSTINCT,  AND  REASON 

learned  nothing,  would  still  be  as  blank  as  that  of  a  newly  born 
infant. 

626.  We  always  measure  the  intelligence  of  an  animal  by  its 
power  of  profiting  by  experience.     Thus,  a  cat  is  more  intelligent 
than  a  rabbit,  because  it  can  learn  more ;    a  dog,  for  the  same 
reason,  is  still  more  intelligent.     An  animal  with  a  purely  instinc- 
tive mind,  with  '  innate  and  inherited '  impulses  to  act  in  this  or 
that  way  but  no  memory,  can  have  no  conception  of  its  past,  and 
therefore  no  idea  of  its  future.     It  lives  wholly  in  the  immediate 
present,    feeling   but   not  thinking.      It  acts    entirely   on  simple 
inclination,  not   on   reflection.     Like  the   caterpillar  building  his 
cocoon,  it  makes  provision  for  the   future,  not  with  any  idea  of 
providing,    but   simply  because   stimulus   from    the   environment 
causes  it  to  react  in  a  certain  way,  gives  it  an  impulse  to  a  certain 
course  of  action  the  performance  of  which  bestows  pleasure  of  the 
kind  that  a  child  derives  from   playing  or  eating,  and  with  the 
ultimate  result  of  which  it  is  no  more  consciously  concerned  than 
a  playing  child.     If  a  caterpillar  sheltered  in  a  hole  with  the  idea, 
founded  on   experience,  of  avoiding  danger,  his  action  would    be 
intelligent.     If,  appealing  to  a  memory,  in  which  a  great  number 
of  complex  experiences  were  stored,  he  took  thought  and  designed 
himself  a  shelter  in  which  provision  was  made  for  all  sorts  of  re- 
membered or  imagined  dangers,  his  action  would  be  rational.     But 
if,  making  no  appeal  to  the  past  nor  taking  any  thought  for  the  future, 
he  builds  only  because  impelled  by  an  '  innate  '  inclination,  then,  no 
matter  how  elaborate  the  edifice  he  rears,  his  action  is  instinctive. 

627.  In  proportion  as  animals  are  low  in  the  scale  of  life,  they 
appear  incapable  of  learning.     Thus,  memory  seems  rudimentary 
or  absent  in  most  insects.    But  often  they  are  wonderfully  equipped 
by  instinct.     To  take,  again,  the  example  of  the  caterpillar:  on 
emerging  from  the  egg,  driven  by  an  innate  inclination  which  is 
the  instinct,  the  animal  moves  from  place  to  place.    It  co-ordinates 
its  muscles  without  practice  perfectly  at  the  first  attempt.     In 
other  words,  its  movements  are  instinctive  in  a  double  sense ;  they 
are  prompted  by  instinct  and  they  are  co-ordinated  instinctively. 
The  animal  does  not  learn  to  do  them.     In  the  human  being,  on 
the  other  hand,  even  when  the  prompting  is  instinctive,  the  power 
of    co-ordinating    the    movements    for   the    performance    of    the 
instinctive  act  is  for  the  most  part  slowly  and  laboriously  acquired 
through  experience.     For  example,  maternal  love  is  an  instinct ; 
but  facility  in  all  the  movements  to  which  the  instinct  prompts  the 
mother  is  '  acquired.' 


INSTINCT  379 

628.  Prompted  by  another  'inherited'  'inborn'  impulse,  the 
caterpillar  seeks  its  proper  food.     Yet  another  instinct  prompts  it 
to  inhabit  such  situations  as  afford  concealment  from  its  enemies. 
Next,  at  a  certain  stage  of  its  growth,  an  instinct  prompts  it  to 
provide  shelter  for  its  helpless  pupal  stage  by  spinning  a  cocoon 
or  by  some  other  device  which  has  been  followed  invariably  by  its 
ancestors.     As  a  butterfly,  it  is  under  the  influence  of  an  entirely 
different  set  of  instincts.     Inhabiting  an  altogether  different  en- 
vironment, it  moves  instinctively  by  means  of  other  organs,  adopts 
new  devices  to  escape  its  enemies,  seeks  and  feeds  in  a  different 
way  on  different  food,   pursues  the  female  and  mates  with  her. 
She,  impelled  by  an  instinct  unfelt  by  the  male,  deposits  her  eggs 
in  one  of  the  few  spots  in  the  vast  and  complex  world  in  which 
she  moves  in  which  her  offspring  will  have  a  chance  of  surviving. 

629.  The  caterpillar  has  sense  organs  and  a  nervous  system  ; 
we  have  every  reason  to  believe  that  it  feels.     But  there  is  little  or 
no  evidence  that  it  remembers  or  thinks.     Memory  would  be  little 
use  to  it;    therefore  parsimonious  nature  bestows  little  or  none. 
Cast  adrift  in  a  hostile  world,  it  must  come  into  existence  ready 
armed  for  the  battle  of  life.     The  necessity  of  following,  by  its 
own  unaided  efforts,  the  right  line  of  action  is  as  pressing  at  the 
beginning  of  life  as  subsequently.     It  has  no  time  to  learn,  and 
during  the  rapid  and  strange  changes  in  its  career  little  oppor- 
tunity of  acquiring  knowledge  which  would  beneficially  affect  its 
future.      Many  of  its    most   important   actions,   such   as   cocoon 
building  and  mating,  are  done  only  once.     Since  memory  and  its 
corollaries,  comparison,  discrimination,  idealism,  imagination,  re- 
flection,   intelligence,   reason,  and  all   that  they  imply  are  most 
developed  in  the  higher  animals  and  are  imperceptible  lower  in 
the  scale,  since  they  gradually  increase  in   number,  range,  and 
utility,  they  are  clearly  later  and  higher  products  of  evolution  than 
instinct.     Memory,  itself,  the  faculty  by  means  of  which  we  learn, 
arises  under  the  stimulus  of  nutriment.     Therefore  it  is  '  inborn.' 
But  all  that  is  stored  in  the  memory,  all  the  mental  growth  which 
arises  through  its   use  and  the  use  of  its  contents  is    'acquired.' 
Therefore  intelligence  and  reason    are    'acquirements.'      A  man 
who  has  no  memory,  whose  mind  is  blank  of  all  that  memory 
supplies,  and  who,  consequently,  cannot  compare,  discriminate,  or 
perform   any  of  the  operations  which  the  possession  of  a  stored 
memory  would  enable  him  to  accomplish,  is  not  intelligent.1     The 
only  mental  operations  possible  to  him  are  sensations  and  instinc- 

1  See  §  762. 


38o        REFLEX  ACTION,  INSTINCT,  AND  REASON 

tive  emotions.  But,  though  intelligence  is  altogether  an  acquire- 
ment, I  think  no  one  will  deny  that  we  speak  correctly  when  we  say 
that  it  has  undergone  evolution  in  the  higher  animals.  Like  many 
instincts  and  physical  characters,  it  arises  late  in  the  development 
of  the  individual  (for  it  arose  late  in  the  evolution  of  the  species), 
but  it  is  none  the  less  as  essential  a  part  of  his  mental  growth  as 
any  trait  which  arises  under  the  stimulus  of  nutriment.  In  fact, 
though  students  of  the  subject  have  never  realised  that  intelligence 
is  an  acquirement,  yet  it  has  been  universally  recognised  that  the 
mental  evolution  of  the  higher  animals  has  consisted  mainly  in 
the  evolution  of  intelligence  and  reason — that  is,  as  we  see  when 
we  think  closely,  of  the  evolution  of  memory  and  of  the  mental 
growth  which  the  possession  of  memory  renders  possible. 

630.  Family  life,  which  is  practised  by  all  the  higher  animals,  is 
not  only  a  product  of  memory  but  is  also  that  which  has  rendered 
possible  the  evolution  of  a  voluminous  memory.     The  offspring  are 
recognized  by  the  mother,  and  in  the  case  of  some  animals  by 
the  father  who  then  recognises  his  mate  also.     This  recognition 
implies  some  degree   of  memory  and   consequently  intelligence. 
The  young,  instead  of  being  cast  adrift  at  birth  to  fend  for  them- 
selves, are  watched  and  protected,  and,  by  the  highest  animals, 
taught.     Time  and  opportunity  are  thus  afforded  for  learning  about 
the  world,  and,  more  particularly,  of  acquiring  the  traditions,  the 
stored  experiences  of  the  race.      Animals  which  have  no  family 
life,  for  example  most  fish,  amphibians  (e.g.  frogs),  and  reptiles, 
may  possess  a  memory,  but  it  is  always  very  rudimentary.     They 
may  learn  a  little  from  experience,  but  only  a  very  little;  their 
intelligence  is  very  low,  their  thoughts  must  be  few  and  simple. 
The  recognition  of  offspring  by  parents  is  usually,  but  erroneously 
assumed  to  be  instinctive.     It  is  certainly  acquired  through  experi- 
ence  after   the   birth.     But   once   the  child  is  known,  the   more 
intelligent  the  animal  the  more  perfect  is  the  subsequent  recogni- 
tion.    The  hen  will  adopt  strange  eggs  and  chickens,  and  even 
ducklings   and  pea  chicks.     The  ewe,  the   cow,   and  the  human 
mother  may  have  strange  offspring  foisted  on  them  immediately 
after  parturition,  but  they  are  not  easily  deluded  after  they  have 
performed  the  first  offices  of  tenderness. 

631.  With  the  opportunity  which  parental  protection  affords  to 
the  young  to  profit  by  experience  comes  the  ability  to  profit  by  it, 
and  with  the  latter  a  proportionate   retrogression   of  now   useless 
instincts.     Intelligence  is  substituted  for  unthinking  impulse.     All 
the  instincts  are  not  lost,  but  in  the  higher  animals  we  find  no  such 


HUMAN  MENTAL  DEVELOPMENT  381 

elaborate  impulses  as  in  the  lower.  Such  a  being  as  the  caterpillar 
is  able  to  fend  for  itself  from  the  first,  but  just  in  proportion  as 
animals  are  intelligent  they  are  helpless  at  the  beginnings  of 
consciousness,  and  correspondingly  capable  later.  A  young  pig 
can  run  as  soon  as  it  is  born,  but  the  acquirements  of  the  '  learned ' 
pig  are  small  compared  to  those  of  a  dog  which  is  more  helpless 
at  birth  but  so  teachable,  so  capable  of  learning,  that  it  becomes 
the  companion  of  man.  All  our  domesticated  animals,  except  such 
small  and  harmless  types  as  silk-worms,  are  teachable,  and  for  that 
reason  we  are  able  to  tame  them.  A  tiger  or  a  leopard  cannot  easily 
be  domesticated  because  instinct  forms  too  large  and  memory  too 
small  a  proportion  of  its  total  mentality.  Domestication,  in  the 
sense  meant,  implies  intelligence,  and  therefore  memory. 

632.  Of  living  beings  man  is  by  far  the  most  helpless  at  birth. 
He  cannot  even  seek  the  breast.     In  him  instinct  is  at  its  minimum 
and  memory  at  its  maximum.     For  him,  more  than  for  any  other 
animal,  is  prolonged  and  elaborate  tuition  necessary.     But,  so  vast 
is  his  memory  and   so   great   his   power  of  utilising  experience 
stored    in   it,   of  growing   mentally   under   the   stimulus   of  use, 
that  in  later  life  he  is  beyond  comparison  the  most  capable  of 
the  inhabitants  of  the  earth.     Compare  what  even  a  dull   man 
knows,  including  the  words  of  a  language  with  their  inflections 
and  articulations,  with  what  is  acquired  by  the  cleverest  dog  or 
monkey  and  the  immensity  of  the  difference  is  at  once  apparent. 
We  may  take  a  frog  and  rear  him  solitary  from  the  egg  in  an 
aquarium.     If,  when  he  is  adult,  we  remove  him  to  a  pond,  he  will 
take  his  place  with  his  fellows  at  once.     He  has  little  if  anything 
to  learn.     Instinctively  he  '  knows '  his  food  and  how  to  seek  it, 
his  enemies  and  how  to  avoid  them,  his  mate  and  how  to  deal  with 
her.     But  how  forlorn  and  helpless  would  be  a  man  reared  from 
infancy  out  of  sight  and  sound  of  his  kind  and  then  turned  into  a 
world  where  his  experienced  fellows  struggled  for  existence. 

633.  Traditional  knowledge — that  is  knowledge   imparted  by 
one  generation   to   the   next — is   common   enough    amongst  the 
higher  animals  and  forms  no  inconsiderable  part  of  their  mental 
equipment.     Thus  we  may  see  the  hen,  impelled  by  an  instinct, 
teaching  her  chickens,  as  she  herself  was  taught,  to  seek  food,  and 
the  cat  teaching  her  kittens  how  to  ambush  mice.      The  young 
animals,  on  the  other  hand,  discover  an  instinctive  interest  and 
pleasure  in  copying  their  elders.     While  insects  and  others  of  the 
lower  type  learn  nothing  from  the  presence  of  man,    birds   and 
mammals  learn  much.     When  inhabiting  desert  islands  they  have 


382        REFLEX  ACTION,  INSTINCT,  AND  REASON 

none  of  that  fear  of  him  which  in  our  country  they  learn  from  dire 
experience.  We  have  a  saying,  "  as  wild  as  a  hawk  "  ;  but  Darwin 
relates  how  he  almost  pushed  a  hawk  from  its  perch  with  the 
muzzle  of  his  gun  in  the  Galapagos  islands.  Sea-birds  round  our 
coasts,  where  they  are  molested,  are  exceedingly  shy ;  at  London 
Bridge  they  feed  from  the  hand.  Formerly  Arctic  seals,  impelled 
by  fear  of  polar  bears,  inhabited  the  outer  margin  of  the  ice  floes  ; 
now  they  have  retreated  from  the  more  dangerous  neighbourhood 
of  man  to  the  landward  edge.  Antarctic  seals,  harried  by  the 
great  carnivora  of  the  ocean,  are  watchful  in  the  water ;  on  land 
or  the  surface  of  the  ice,  where,  till  lately,  they  met  no  danger,  they 
may  be  slaughtered  like  sheep  in  the  shambles.  They  are  capable 
of  profiting  by  experience,  but  they  are  slow  to  learn,  and  can 
acquire  but  little.  Judged  by  our  human  standard  they  are  very 
stupid.  The  means  of  escape  adopted  by  Arctic  seals  compared 
with  the  means  of  capturing  them,  the  ships,  guns,  and  the  rest, 
afford  a  measure  of  the  intellectual  difference. 

634.  When  animals  are  social  and  so  have  the  opportunity  of 
learning,  not  only  from  their  parents  but  also  from  other  members  of 
the  species,  the  power  of  making  mental  acquirements  and  conse- 
quently of  handing  on  the  traditions  of  the  race  is  often  correspond- 
ingly great.     It  reaches  a  remarkable  degree  of  development  even 
amongst  insects,  some  species  of  which  live  in  great  communities. 
Young  ants  are  carefully  tended  and  are  said  to  receive  instruction 
from  their  elders.     A  capacity  to  profit  by  experience  implies,  of 
course,    memory.      There   is,    however,   more    decisive   evidence. 
Some  species  of  ants  have  the  habit  of  capturing  the  pupae  of  other 
species  and  of  so  training  the  young  individuals  that  develop  from 
them  that  they  peform  duties  which  were  quite  unknown  to  their 
ancestors.     Therefore  it  is  clear  that  the  slaves  profit  by  experience. 
Consequently  their  actions  are  intelligent  not  instinctive. 

635.  So  important  are  the  duties  of  the  slaves,  so  much  do  they 
learn,  so  long  has  the  habit  of  slave-making  been  followed  by  their 
masters,  that  in  some  species  the  latter  have  evolved  into  mere 
fighting  machines,  incapable  even  of  feeding  themselves.     Many 
important     physical     and    mental     characters    have     undergone 
retrogression  in  them — not  through  lack  of  use,  for  doubtless  the 
animals   used    while   they    possessed    them,    nor    even   through 
lack  of  utility,  for  powers  of  self-feeding  must  have  always  been 
useful,  but  solely  through  lack  of  sufficient  survival  value.     That  is 
to   say,   the   parts,   however   much   used   and    useful,   underwent 
retrogression   because  the  acquirements  of  the  slaves  supplied  a 


THE  INSTINCTS  OF  MAN  383 

substitute  so  efficient  that  individuals  (or  rather  the  communities) 
that  possessed  them  in  higher  degrees  did  not  survive  in  greater 
numbers  than  those  that  possessed  them  in  lower  degrees.  Since 
ants  possess  such  high  powers  of  making  mental  acquirements,  it 
is  only  reasonable  to  suppose  that  their  instincts,  like  those  of  man 
and  like  many  of  the  mental  and  physical  parts  of  the  slave-holders, 
have  undergone  retrogression.  Whence  it  follows  that  many  of 
their  so-called  instincts — for  example  the  habit  of  warring  in  dis- 
ciplined hosts,  of  keeping  pets,  of  preserving  aphides  for  the  sake 
of  their  sweet  secretions,  of  clearing  areas  of  ground,  growing  food 
plants  on  them,  and  storing  the  seed,  of  nipping  the  rootlets  of 
seed  to  prevent  germination,  and  so  forth — are  quite  possibly,  not 
instincts  but  items  of  traditional  knowledge  and  habits  entirely 
comparable  to  that  traditional  knowledge,  to  those  traditional 
mental  attitudes,  those  ways  of  thinking  and  acting,  which  play  so 
large  a  part  in  human  lives. 

636.  The  instincts  of  man,  though  comparatively  few  and 
simple  and  though  overshadowed  by  the  enormous  mass  of  his 
acquired  mental  characters,  by  his  intelligence,  are  yet  essential  to 
his  existence.  Some  of  his  actions  are  wholly  instinctive,  for  not 
only  are  the  inclinations  to  perform  them  innate,  but  also  the  ability 
to  do  so.  The  act  of  sucking  in  a  young  infant  is  an  example. 
This  action  is  often  termed  a  reflex.  But  it  is  entirely  voluntary 
in  the  adult.  No  man  ever  sucks  unless  he  chooses  to  suck.  If, 
then,  it  is  reflex  in  the  infant,  it  must  altogether  change  its  char- 
acter later  which  no  other  reflex  is  known  to  do.  Thus,  though 
we  may  learn  to  breathe  and  cough,  yet  we  continue  to  do  both 
because  we  must.  Sucking,  on  the  other  hand,  is  always  voluntary 
in  the  sense  that  it  is  invariably  prompted  by  an  emotion,  a 
desire,  and  that  it  is  initiated  by  the  will.  Doubtless  the  new 
born  infant  does  not  consciously  desire  milk  (of  which  [it  has  no 
previous  experience)  when  it  sucks,  any  more  than  a  child  desires 
bodily  development  when  it  plays.  But  when  the  emotion  is 
awakened  by  the  mother's  nipple  the  act  itself  is  delightful  and  is 
instinctively  performed  as  long  as  the  delight  continues — that  is 
while  the  milk  flows  and  the  hunger  is  unsatisfied.  Were  there  no 
prompting  emotion,  no  delight,  the  act  would  not  be  performed. 
Crying,  an  act  prompted  by  discomfort  or  pain,  is  also  entirely 
instinctive  at  first.  The  function  of  the  cry  is  an  appeal  for  aid  ; 
but  here  again  the  infant  has  no  notion  of  its  real  meaning.  It 
cries  only  because  it  is  impelled  by  a  certain  emotion,  the  instinct, 
to  a  certain  act,  the  instinctive  act.  Yet  again  when  tired  or 


384         REFLEX  ACTION,  INSTINCT,  AND  REASON 

sleepy,  we  instinctively,  without  learning,  place  ourselves  in  an 
attitude  of  rest.  Doubtless  we  learn  in  time  what  attitudes  are 
most  comfortable,  but  no  learning  is  needed  to  secure  cessation 
of  movement  and  relaxation  of  all  our  voluntary  muscles  and  the 
consequent  assumption  of  a  restful  position. 

637.  Hunger  and  thirst  are  terms  which  are  applied  both  to  the 
instinctive  desires  to  take  food  and  water  and  to  the  antecedent 
sensations   which   awaken    them.     Thus,    when   we   say   we   are 
hungry  we  may  mean  either  the  feeling  of  discomfort  in  the  region 
of  the  stomach,  or  the  wish  for  food,  or  both.     The  recognition  of 
food  as  such  by  the  sense  of  taste  is  also  instinctive.     Normally 
we  eat  and  drink  only  nutritive  substances,  those  which  contain 
food  or  water,  with  pleasure.     Probably,  however,  this  instinct  is 
more  perfect  in  the  lower  animals  than  in  man  in  whom  it  seems 
to  have  undergone  some  retrogression.     The  infant,  protected  as 
it  is  by  its  mother's  intelligent  care,  tends  to  swallow  any  small 
object  that  comes  to  hand  ;  the  caterpillar  and  the  puppy,  which 
is  aided  by  its  sense  of  smell,  are  rarely  in  fault.     In  all  animals 
the  amount  of  food  desired  is  limited  by  the  needs  of  the  individual, 
though  even  in  this  case  the  instinct  appears  more  perfect  in  the 
lower  animals  than  in  man.     Instinctive  also  are  those  voluntary 
movements  of  tongue  and  jaws  which  occur  when  food  or  water 
is  placed  in  the  mouth.     Unlike  the  caterpillar,  however,    man 
must   learn  all   those   actions   by   means  of  which   he   procures 
food. 

638.  The  impulse  to  play  is  an  instinct,  but  it  prompts  to  no 
action  for  which  our  muscles  are  instinctively  co-ordinated.      Its 
sole  function  is  to  impel  us  to  make  physical  and  mental  acquire- 
ments.    Under  its  influence  we  use  our  bodies  and  minds  which 
develop  in  response  to  the  stimulus  thus  supplied  till  we  are  fitted 
to  the  ancestral  environment.     We  have  already  dealt  at  length 
with    physical     use-acquirements.1       The    mental    acquirements 
resulting  from  play  are  strictly  homologous  and  not  less  important. 
They  enable  us  to  co-ordinate  our  muscles  for  purposeful  action 
and  so   perform  our  voluntary  actions  as  swiftly  and   surely  as 
reflexes.     The  vague  movements  of  the  infant  become  purposeful 
if  awkward  ;  his  awkward  movements  become  easy  and  sure ;  and 
these  easy  movements  at  length  become  '  automatic.'     Only  those 
animals  sport  which  make  physical  and  mental  acquirements,  and 
they   sport   only   when    play   is    useful,   and    in    a   way   that    is 
useful.     The  caterpillar  does  not  sport ;  he  has  no  physical  and 

1  See  chapter  i. 


PLAY,  IMITATIVENESS,  AND  CURIOSITY          385 

mental  '  acquirements '  to  make ;  his  actions  are  all  entirely 
business-like.  It  is  true  that  gnats  and  other  insects  indulge  at 
certain  seasons  in  dances  which  appear  to  us  sportive ;  but  there 
is  every  reason  to  believe  that  they  are  impelled,  not  by  the 
playing,  but  by  the  sexual  instinct.  On  the  other  hand,  young 
ants  are  said  to  be  sportive.  The  young  of  the  higher  animals 
are  playful  in  proportion  to  the  extent  to  which  their  bodies  and 
minds  are  capable  of  development  under  the  stimulus  of  use.  In 
each  instance  the  sport  is  exactly  adapted  to  fit  the  individual  for 
the  future  business  of  life.  The  little  girl  '  naturally '  turns  to  her 
doll,  which  she  nurses  as  she  will  her  baby.  The  play  of  the  boy 
as  naturally  involves  contests  which  foreshadow  the  grimmer 
struggles  of  adult  life.  As  he  grows  older  the  character  of  his 
sport  changes.  More  and  more  it  becomes  an  affair  of  wit  and 
dexterity,  an  appeal  to  wider  experience,  and  a  means  of  adding  to 
it.  When  the  girl's  play  with  her  doll  and  the  sports  of  the  little 
boy  have  served  their  purpose  and  ceased  to  be  useful,  they  cease 
also  to  excite  interest.  Compare  the  ambush  and  pounce  of  the 
kitten,  the  ardent  chase  and  overthrowing  of  the  puppy,  and  the 
climbing  proclivities  of  the  monkey  and  the  kid.  When  full 
physical  and  mental  development  is  attained,  the  desire  for  sport 
wanes.  It  lingers  longest  in  the  most  intelligent  animals,  those 
whose  memories  are  the  most  capacious,  who  are  most  capable  of 
profiting  from  experience.  Little  remains  of  the  instinct  in  the 
adult  cat  or  horse ;  the  dog  retains  it  longer ;  while  man,  who  is 
capable  of  learning  even  in  old  age,  retains  it  in  some  measure  to 
the  end.  Hence,  for  example,  his  pleasure  in  billiards  and  cards. 

639.  Imitativeness  and  curiosity  are  instincts  which  impel  the 
young  individual  to  store  his  mind  with  useful  traits.  Like 
sportiveness,  they  are  developed  in  every  species  in  proportion  to 
the  power  of  making  mental  acquirements,  and  they  persist  in  the 
individual  only  as  long  as  they  are  useful.  Imitativeness  impels 
him  to  copy  his  progenitors,  and  so  make  for  himself  those 
acquirements  which  enabled  them  to  exist  and  rear  offspring  in 
their  world.  The  kitten,  the  puppy,  and  the  monkey  may  be 
seen  observing  with  interest  and  subsequently  imitating  their 
elders.  The  most  imitative  of  all  living  beings  is  a  child,  who 
from  the  time  he  copies  his  elders  in  walking,  speaking,  and 
manipulative  dexterity,  to  the  time  when  he  acquires  his  ultimate 
political  and  religious  notions,  is  constantly  under  the  influence  of 
this  instinct.  A  large  part  of  a  little  child's  sport  consists  in  pre- 
tending to  be  such  and  such  a  person,  or  to  do  such  and  such  a 
25 


386        REFLEX  ACTION,  INSTINCT,  AND  REASON 

thing.  All  acting  is  imitating,  and  much  of  a  child's  play  is 
acting.  Fashion  is  nothing  other  than  a  manifestation  of  imitative- 
ness  ;  the  infectious  fury  of  mobs,  and  the  steadfast  purpose  of 
men  in  armies,  is  little  more.  Human  society,  which  could  not 
exist  unless  the  units  composing  it  were  much  alike,  is  founded  on 
it.  It  is  the  principal  means  by  which  the  traditions  of  the  race 
are  transmitted  to  remote  generations. 

640.  The  function  of  curiosity  is  obvious.     Like  imitativeness, 
it  impels  to  the  acquirement  of  useful  mental  characters.     Almost 
as  strong  in  the  adult  as  in  the  child,  it  persists  in  men  throughout 
life.     It  is  alike  conspicuous  in  the  aged  gossip  and  in  the  man  of 
science. 

641.  Sexual  love  is  an  instinct  which  prompts  to  actions  which, 
like  swimming,  are  instinctive  in  the  lower  animals,  but  which  man 
acquires  the  ability  to  perform.     At  any  rate,  the  ability  to  perform 
all  the  actions  which  lead  up  to  the  sexual  act  are  acquired  by  him. 
The  instinct  is  better  developed,  as  a  rule,  in  men,  who  play  an 
active  part,  than  in  women,  who  play  a  passive  part.     No  man  could 
have  offspring  unless  he  had  the  instinct ;  but  women,  who  in  past 
times  have  often  been  the  helpless  slaves  of  their  masters,  may 
have  offspring  in  the  absence  of  sexual  inclination. 

642.  Parental  love  is  an  instinct  which  impels  to  the  care  ol 
offspring ;  but  none  of  the  actions  prompted  by  it  are  instinctively 
performed  by  human   beings.     The  lower  animals   are   innately 
capable  of  tending  their  young  ;  but  the  human  mother  must  not 
only   learn  during  her  own    infancy  to  co-ordinate   her  muscles 
for  the  tending  of  a  child,  but  she  must  learn  from  other  mothers 
how  to  do  it.     However,   some  innate  maternal  impulses,  which 
prompt  to  actions  that  need  no  special  learning,  survive.     Thus 
almost  every  human  mother  delights  in  teaching  her  child  to  walk 
and  speak,  characters  which  are  essential  to  its  well-being.1     Very 
beautiful  and  illuminating  is  the  pleasurable  participation  of  even 
dull  and  care-worn  women  in  the  play  of  their  babies  and  very 
young  children.     Parental  love  is  more'highly  developed  in  women 
than  in  men.     In  "  the  state  of  nature  "  in  which  the  race  evolved, 

1  Apart  from  the  parental  instinct,  the  pleasure  we  feel  in  imparting  information 
seems  as  instinctive  as  the  pleasure  felt  in  receiving  it.  Every  normally  con- 
stituted individual  delights  to  awaken  interest  in  this  way.  To-day,  for  example, 
we  bought  my  little  boy,  for  use  in  school,  a  pair  of  drawing  compasses,  a  pro- 
tractor, and  a  set  square.  It  is  many  years  since  I  handled  these  instruments, 
but  I  remembered  some  of  their  uses,  and  I  am  sure  the  child  was  not  more  eager 
and  pleased  in  learning  than  I  was  in  teaching.  The  utility  of  both  the  imparting 
and  the  receiving  instincts  are  very  obvious. 


MENTAL  TRAITS  OF  CATERPILLAR  AND  MAN      387 

a  child  might  survive  its  father's,  but  not  its  mother's  neglect.  The 
mother  who  lacked  parental  instinct  left  few  offspring  behind  her. 
Complementary  to  the  mother's  instinct  to  tend  her  offspring  is  the 
latter's  delight  in  and  acceptance  of  her  care.  For  example,  the 
cat's  instinct  to  carry  her  kitten  in  a  particular  way  (by  the  skin  of 
the  neck)  is  associated  with  the  passive  attitude  of  the  kitten — in 
all  except  the  tail,  which  is  tucked  out  of  harm's  way — when  it  is 
so  carried. 

643.  To  sum  up,  the  caterpillar,  and  all  animals  at  a  similar 
stage  of  evolution,  are  mentally  a  mere  bundle  of  sensations  and 
instincts.     The  latter,  which  lie  latent  till  they  are  awakened  in 
due  season  by  the  former,  develop  under  the  influence  of  nutriment, 
and  are  nothing  other   than  emotions  or  desires  which  impel  to 
the  performance  of  certain  definite  actions,  the  instinctive  actions, 
the  capacity  to  perform  which  is  also  innate.     On  the  other  hand, 
man  has,  not  only  sensations  and  instincts,  but  a  memory.     He 
develops  mentally,  not  only  under  the  stimulus  of  nutriment,  but 
also  under  that  of  experience  (use).     His  power  of  feeling  sensa- 
tions and  instinctive  impulses  is  innate.     His  memory,  his  power 
of  making  mental  acquirements  under  the  stimulus  of  experience, 
is  also  innate.     But  all  that  is  stored  in  his  memory,  all  that  comes 
to    it   through   the   sensations   and    emotions    he  feels   and   the 
conscious   and   unconscious   inferences    he   draws   from   them   is 
acquired.    Mentally,  therefore,  he  is  a  bundle  of  (i)  sensations  ;  (2) 
instincts,  which  in  him  are,  in  most  cases,  merely  incitements  to 
make  acquirements ;  (3)  capacities  for  making  acquirements  (i.e. 
memory)  ;   and   (4)   actual   acquirements.     Since    the   caterpillar 
feels,  he  has  a  mind.     Man  not  only  feels,  but  thinks.     He  has  not 
only  sensations  and  instincts,  but,  in  addition,  an  intellect.     The 
evolution  of  mind  is  beautifully  recapitulated  by  the  stages  of 
the  mother's  care  for  her  offspring.     Up  to  the  time  of  birth,  the 
care  is  entirely  reflex.     After  birth,  it  is  instinctive  in  the  higher 
animals.     In  still  higher  animals,  intelligence  steps  in,  and  both 
aids,  and  to  some  extent  replaces,  instinct.     Thus  it  is  intelligence, 
not  instinct,  that  impels  us  to  send  our  children  to  school. 

644.  It  is  not  possible,  of  course,  to  indicate  precisely  the  stage 
of  evolution  (i.e.  the  kind  of  animal)  in  which  sensations  first 
appeared  as  sparks  to  explode  reflex  action,  and  in  which,  there- 
fore, mind  dawned.     Nor  is  it  possible  to  indicate  when  sensations 
first  took  on  tones  of  pleasure  and  pain,  when  desire  and  will  awoke, 
and  instinct  and  voluntary  action  appeared.     Nor  again  can  we 
indicate  when  memory  began,  and  brought  in  its  train  as  it  evolved 


388        REFLEX  ACTION,  INSTINCT,  AND  REASON 

thought  and  intellect,  intelligence  and  reason.  But  the  fact 
remains  that  all  these  faculties  are  products  of  evolution,  means  by 
which  individuals  and  races  are  adapted  to  their  environments. 
They  all  arose  from  small  beginnings,  and  increased  gradually  with 
the  needs  of  the  species  as  its  relations  with  the  environment 
grew  more  and  more  complex.  Sensation  followed  reflex 
action,  instinct  followed  sensation,  memory  followed  instinct,  and 
intelligence  memory. 

645.  The  mental  traits — sensations,  desires,  instincts,  memory, 
intelligence — fit  in  exquisitely  with  the  physical  traits — skin,  bone, 
blood-vessel,  nerves,  reflexes,  and  all  the  rest.  In  mind  and  body 
the  living  animal  is  an  immensely  complex  and  wonderfully 
adjusted  machine — a  machine  vastly  more  complex  and  perfectly 
adjusted  than  anything  that  has  ever  been  invented  by  man  as  the 
work  of  his  hands  and  brain.  A  single  important  adaptive  change 
in  this  machine  cannot  occur  separately.  It  must  involve  a 
thousand  or  ten  thousand  readjustments,  a  thousand  correspond- 
ingly important  changes  in  mind  and  body.  Thinking  of  all  this, 
we  realize  the  full  force  of  the  statement  that  the  organism  is  a 
bundle  of  adaptations  and  co-adaptions.  We  realize  also  the  full 
force  of  the  main  objection  to  the  mutation  theory.  It  is  possible 
to  accept  that  theory  if  we  think  only  of  such  things  as  the  colours 
and  shapes  of  leaves,  or  other  changes  which  do  not  necessarily 
ruin  co-adaptation.  But  when  we  take  the  whole  of  the  facts 
into  consideration,  when  we  think  of  the  complex  way  in  which 
the  mental  and  physical  adjustments  of  the  higher  animals  inter- 
lock and  how  fine  the  adjustment  is,  we  are  driven  to  the  conclusion 
that  evolution  can  have  been  founded  only  on  the  continual 
selection  and  blending  of  multitudes  of  small  variations,  by  means 
of  which  all  co-adapted  parts  underwent  change  together,  and  the 
organism  was  moulded  as  a  whole.  In  other  words,  we  are  forced 
to  believe  that  nature  selected  for  survival,  not  individuals  who 
varied  widely  from  the  rest  of  the  species  in  this  or  that  particular, 
but  individuals  who  varied  comparatively  little  as  regards  the 
size  of  their  variations,  but  much  as  regards  the  number  of  their 
variations,  and  who,  therefore,  were  better  adapted  on  the  whole 
to  the  gradually  changing  environment  than  their  fellows  that 
perished ;  and  who  blended  their  variations,  so  that  it  was  not  so 
much  the  successful  appeal  of  the  individual  that  counted  in  the 
racial  struggle  for  persistence,  but  the  experience  of  the  entire 
species  or  variety.  Indeed,  notwithstanding  the  wealth  of  material 
furnished  by  fluctuations,  so  vast  is  the  complexity  of  the  higher 


THE  ACQUIREMENTS  OF  THE  NORMAL  MAN      389 

organisms,  and  so  delicate  the  adjustment  of  their  parts  and 
faculties,that  many  thinkers  have  been  driven,  in  spite  of  the  fact  that 
there  is  apparently  no  alternative,  to  doubt  whether  Natural  Selec- 
tion is  adequate  for  the  task.  Our  faith  is  restored  only  when 
we  contemplate  the  special  and  beautiful  devices  which  Natural 
Selection  has  evolved  to  help  its  work  of  adaptation  and  co- 
adaptation — on  the  one  hand,  bi-parental  reproduction  and  the 
tendency  of  retrogressive  variations  to  preponderate  over  pro 
gressive  variations,  both  of  which  automatically  plane  away  all 
redundancies ;  and,  on  the  other,  the  power  of  developing  under  the 
stimulus  of  use  which  brings  about  co-adaptation  in  the  characters 
of  the  individual  through  the  influence  which  related  parts  and 
faculties  exercise  over  one  another's  growth. 

646.  Again  we  have  seen  how  much  neglected  has  been  the 
study  of '  acquirements ' ;  it  has  even  been  supposed  that  evolution 
is  founded  entirely  on  ' inborn'  traits.    But  consider  what  man 
would  be  without  his  mental  acquirements.     The  congenital  idiot 
and  the  normal  man  start  life  equal,  except  in  one  particular.    The 
idiot  has  little  or  no  memory,  no  power  of  learning,  no  power  of 
growing  mentally  under  the  stimulus  of  experience,  whereas  the 
normal  man  has  that  power.     This,  at  birth,  is  the  sole  difference 
between  the  two.1     But  an  empty  memory,  a  mere  possibility  of 
learning,  is  nothing.     If  the  normal  man  had  not  filled  his  memory, 
he  also  would  be  an  idiot.     Now  is,  or  is  not,  the  intelligence  of 
the  normal  man,  which  has  arisen  only  because  he,  personally,  has 
made  acquirements,  a  product  of  evolution  ?     Is  not  this  mental 
growth,    which    consists    entirely    in    acquirements,    and    which 
separates  him  mentally  from  such  animals  as  the  idiot  and  the 
caterpillar,  as  much  a  part  of  his  normal  growth  as  his  head  or 
his  instincts  ?     If  it  is,  then  surely,  the  study  of  acquirements, 
including  the  entire  field  of  the  intellect,  is  at  least  as  well  worth  the 
attention  of  the  student  of  nature  as  the  study  of  any  other  class 
of  character. 

647.  It    may  be   argued   that  'the   task   of    the   biologist   is 
complete  when  he  has  traced  the  growth  of  memory,  which  is  all 
that  is  inborn,  and,  therefore,  all  that  has  undergone  evolution.' 
But  to  this  there  are  two  sufficient  answers.      First,  no  serious 
attempt  has  ever  been  made  to  trace  the  evolution  of  memory. 
Though  it  is  the  foundation  of  all  intelligence,  it  has,  of  all  mental 
characters,  been  the  most  neglected  by  biologists  in  general  and 
psychologists  in  particular.     Indeed  to  this  day  there  are  some 

1  See  §§  762,  et  seq. 


390        REFLEX  ACTION,  INSTINCT,  AND  REASON 

who  suppose  that  memory  (like  extension  in  space)  is  a  property 
of  all  living  protoplasm,  and  who  attribute  it,  therefore,  even  to 
the  protozoa  and  to  plants.  Others,  declaring  that  without  memory 
there  can  be  no  feeling,  place  the  beginnings  of  the  faculty  at  the 
beginnings  of  conscious  life.  Second,  if  we  regard  the  power  of 
growing  mentally  under  the  stimulus  of  experience  as  the  essential 
thing,  and  the  intelligence  and  reason  which  result  from  the  exercise 
of  this  power  as  accidents,  even  then,  if  we  are  consistent,  we 
must  regard  all  the  characters  of  living  beings,  including  memory, 
as  accidents ;  for,  in  exactly  the  same  sense,  all  'inborn  '  characters 
arise  merely  because  there  has  been  evolved  a  power  of  developing 
under  stimulus — in  this  case  that  of  nutriment.  Here,  then,  is 
the  point  on  which  I  wish  to  fix  the  reader's  attention.  As  he 
peruses  the  remaining  chapters  of  this  book,  he  must  constantly 
bear  in  mind,  not  only  that  he  is  studying '  acquirements  I  but  that 
acquirements  are  products  of  evolution,  parts  of  normal  growth, 
characters  without  which  the  individual,  who  belongs  to  a  species 
which  has  evolved  the  power  of  making  them,  cannot  achieve  complete 
maturity.  If  we  study  mind  from  this  point  of  view,  we  shall  not 
only  observe  it  in  a  light  that  is  new,  but  also  in  one  which  will, 
I  think,  enable  us  to  penetrate  more  deeply  into  its  mysteries 
than  has  been  possible  hitherto. 

648.  The  reader  perceives  that  I  am  what  is  termed  an 
'  extreme '  Darwinian  or  Selectionist.  Indeed  I  am  a  very  extreme 
Darwinian.  For  me  the  great  outstanding  truth  concerning  living 
beings  is  the  wonderful  closeness  with  which,  notwithstanding  the 
vast  multitude  and  diversity  of  species  and  characters,  they 
are  all  adjusted  by  all  their  structures,  faculties,  and  chemical 
reactions  (for  the  individual  is  a  complex  chemical  factory)  to  their 
environments — an  adjustment  which  includes  an  equally  close 
adjustment  of  their  parts  and  faculties  to  one  another,  as  well 
as  such  fundamental  characteristics  as  the  degree  of  variability 
of  each  character,  and  the  normal  limitation  of  variability  to  a 
portion  of  the  germ-tract.  Experience  tells  me  that  just  in 
proportion  as  I  increase  my  knowledge  of  any  species,  I  am  forced 
to  believe  that  parsimonious  nature  has  bestowed  on  it  little  or 
nothing  but  adaptations.  Of  necessity  I  know  my  own  species 
best ;  and  I,  a  medical  man,  can  think  of  hardly  a  human  structure 
or  faculty  to  which  I  am  unable  to  assign  a  useful  function.  I 
know,  and  as  a  human  being  can  know,  comparatively  little  about 
species  that  are  far  remote  from  my  own,  such  as  beetles,  butter- 
flies and  plants ;  and  of  the  uses  of  their  structures  and  faculties 


ADAPTATION  391 

I  am  correspondingly  ignorant.  But,  when  I  see  in  such  a  species 
a  structure,  the  function,  the  utility,  of  which  I  am  too  ignorant 
to  perceive,  I  do  not  leap  to  the  conclusion  that  it  has  no  function, 
or  no  useful  function.  J  remember  my  own  species,  and,  bearing  in 
mind  that  all  species  apparently  fit  their  environments  as  well  as 
my  own,  I  seek,  if  possible,  to  learn  the  function  and  usefulness 
of  the  structure.  Even  when  I  fail,  which  is  very  often,  I  yet 
remain  convinced  that  almost  certainly  both  the  function  and  the 
usefulness  exist. 

649.  From  the  time  that  Darwin  taught  that  plants  and 
animals  had  undergone  evolution  for  their  own  benefit,  not  for 
that  of  men,  this  opinion  has  been,  until  very  recently,  the  accepted 
scientific  view.  But  now  a  new  school  of  thought,  or  if  not  of 
thought  at  least  of  opinion,  has  arisen,  which  (as  may  be  judged 
from  the  following  passages,  examples  of  many  that  might  be 
quoted)  tells  us  that  more  correct  and  less  dogmatic  is  the  opinion 
that,  in  many  instances  at  least,  the  structures  of  remote  species 
have  not  been  evolved  because  of  their  usefulness,  but,  on  the 
contrary,  have  come  into  being  and  have  persisted  in  spite  of  a 
complete  uselessness.  "  The  claim  of  the  opponents  of  the  theory 
that  Darwinism  has  become  a  dogma  contains  more  truth  than 
the  nominal  followers  of  this  school  find  pleasant  to  hear ;  but  let 
us  not,  therefore,  too  hastily  conclude  that  Darwin's  theory  is 
without  value  in  relation  to  one  side  of  the  problem  of  adaptation ; 
for,  while  we  can  profitably  reject,  as  I  believe,  much  of  the  theory 
of  natural  selection,  and  more  especially  the  idea  that  adaptations 
have  arisen  because  of  their  usefulness,  yet  the  fact  that  living 
things  must  be  adapted  more  or  less  well  to  their  environments  in 
order  to  remain  in  existence  may,  after  all,  account  for  the  wide- 
spread occurrence  of  adaptation  in  animals  and  plants."1  "To 
imagine  that  a  particular  organ  is  useful  to  its  possessor,  and  to 
account  for  its  origin  because  of  the  imagined  benefit  conferred, 
is  the  general  procedure  of  the  followers  of  this  school."  2  The 
writer  is  mistaken.  The  'claim'  that  evolution  is  other  than 
adaptation  appears,  not  so  much  unpalatable  as  absurd  to  the 
followers  of  Darwin ;  the  reasoning  by  which  it  is  supported 
excites,  not  chagrin,  but  amazement.  The  following  is  a  case 
in  point.  "  As  an  example  of  a  change  in  the  organism  that  is 
of  no  use  to  it  may  be  cited  the  case  of  the  turning  white  of  the 
hair  in  old  age  in  man  and  in  several  other  mammals.  The 
absorption  of  bone  at  the  angle  of  the  chin  in  man  is  another 

1  T.  H.  Morgan,  Evolution  and  Adaptation,  p.  ix.  *  Op.  cit.,  p.  453. 


392        REFLEX  ACTION,  INSTINCT,  AND  REASON 

case  of  a  change  of  no  immediate  use  to  the  individual.  We  also 
find  in  many  other  changes  that  accompany  old  age,  processes 
going  on  that  are  of  no  use  to  the  organism,  and  which  may,  in 
the  end,  be  the  cause  of  its  death.  Such  changes,  for  instance, 
as  the  loss  of  the  vigour  of  the  muscles,  and  of  the  nervous  system, 
the  weakening  of  the  heart,  and  partial  failure  of  many  of  the 
organs  to  carry  out  their  functions."  x 

650.  "Though  there  is  no  question  of  absolute  perfection  in 
nature,  it  appears  that,  under  given  conditions,  adaptation  is  and 
was  sufficiently  perfect  to  make  it  very  difficult  to  put  one's  finger 
on  any  defect.  When  we  think  we  can  do  so,  it  generally  turns 
out  that  the  defect  is  in  the  mind  of  the  critic  rather  than  in  the 
organism  criticized."  2  Occasionally  we  are  told  that  the  palaeonto- 
logical  evidence  lends  support  to  the  mutation  theory  in  that  an 
examination  of  the  records  stored  in  the  strata  of  the  earth 
indicates,  as  a  rule,  not  gradual  changes  of  type,  but  sudden 
changes.  The  nature  of  this  evidence  may  be  judged  by  any 
one  who  makes  a  careful  examination  of  the  cut  surfaces  of 
ditches  and  canals.  If  by  means  of  such  an  examination  he  is 
able  to  achieve  a  knowledge  of  the  fauna  and  flora  now  inhabiting 
our  planet  sufficiently  minute  and  detailed  to  enable  him  to 
indicate  the  mode  of  origin  of  our  new  varieties,  then,  allowing 
for  the  destructive  effects  of  immensely  longer  time,  he  will  have 
some  title  to  declare  that  strata  deposited  in  past  ages  furnish 
evidence  of  value  concerning  not  only  changes  of  type,  but  of  the 
mode  of  change.  In  that  case,  however,  since  the  changes  found 
in  geological  strata  are  very  vast,  and  since  the  connecting  links, 
if  any,  are  absent,  he  must  decide  in  favour,  not  of  the  hypothesis 
that  animals  and  plants  have  arisen  by  mutation,  but  in  favour  of 
the  hypothesis  that  they  have  arisen  by  special  creation  ;  for  not 
even  the  most  ardent  mutationist  will  maintain,  for  example,  that 
marsupials  suddenly  gave  origin  to  placental  mammals. 

1  Op.  cit.t  p.  25  ;  see  also  §  359  of  the  present  work. 

*Dr  D.  H.  Scott,  Presidential  Address,  Linnean  Society,  May  24th,  1909. 
Nature,  July  22nd,  1909,  p.  115  ;  see  also  §  86. 


CHAPTER  XXI 
THE  EVOLUTION  OF  MEMORY 

The  evolution  of  mind — Definition  of  memory — Distinction  between  memory 
and  its  contents — Memory  stores  most  actively  in  the  young — Memory  does  not 
grow  with  use — A  vast  memory  is  the  distinguishing  peculiarity  of  the  human 
being — The  mental  distinctions  between  ancient  and  modern,  savage  and  civilized 
men — Distinction  between  man  and  the  lower  animals — Conscious  and  uncon- 
scious memory — Distinction  between  reflex  and  automatic  action — The  stereo- 
typing of  mental  acquirements — As  we  sport  with  our  bodies,  so  we  sport  with 
our  thoughts — There  is  no  impassable  mental  gulf  between  man  and  the  lower 
animals — The  neglect  of  memory  by  writers  on  evolution — Darwin — Spencer — 
Romanes — Lloyd  Morgan — Baldwin — The  Mendelians — The  Biometricians. 


A' 


651.  ^  CCORDING  to  the  theory  of  mental  evolution  formu- 
lated in  the  preceding  chapter,  mind  is  not  derived 
from  the  non-mental.  Just  as  life  was  quite  a  new 
thing  in  the  world  when  it  first  appeared,  just  as  nervous  tissue 
however  gradual  its  evolution  was  new,  just  as  manipulation  was 
new,  so  was  that  particular  function  of  nervous  tissue  which  we  term 
mind.  No  doubt  living  cells  and  the  chemical  elements  of  which 
they  are  compounded  preceded  nervous  tissue,  but  that  particular 
combination  of  a  certain  class  of  living  cells  and  fibrils  to  which 
we  apply  the  term  had  no  previous  existence.  So  also  its  function 
— one  of  its  functions — mind  had  no  previous  existence,  nor  even 
an  antecedent  which  remotely  resembled  it.  If  this  hypothesis  be 
correct,  mind  in  its  earliest  beginnings  was  associated  with  a  series 
of  variations  of  nervous  tissue  which  proved  favourable.  It 
appeared  at  first  in  the  form  of  rudimentary  sensations  which 
served  as  sparks  to  explode  reflex  actions — dim  and  faint  percep- 
tions of  light,  heat,  sound,  touch,  and  the  like,  which  were  more 
delicate  and  discriminating  than  the  stimuli  that  had  hitherto 
awakened  action.  The  individual  now  received  stimuli  from  a  wider 
and  more  complex  environment ;  and  his  actions,  which  became 
correspondingly  more  numerous  and  varied,  were  adapted  to 
meet  more  and  more  distant  contingencies,  and  achieve  ends  more 
and  more  remote.  Later  to  mere  sensations  were  gradually  added 
tones  of  pleasure  and  pain,  with  which  came  desire  and  its  corollary 
the  will,  and  with  all  a  further  increase  of  complexity  of  action  and 


394  THE  EVOLUTION  OF  MEMORY 

remoteness  of  aim.  Compare,  for  example,  the  simplicity  of  the 
internal  sensationless  reflexes  of  a  butterfly,  and  the  immediate 
ends  to  which  they  are  directed,  with  the  complexity  and  remote- 
ness of  aim  of  the  actions  to  which  he  is  aroused  by  feelings  of 
hunger  or  sexual  desire,  or  by  the  sight  of  danger.  Lastly  when, 
owing  to  the  evolution  of  many  reflexes  and  instincts,  the  nervous 
system  had  grown  highly  complex,  memory  arose,  though  not  of 
course  as  a  necessary  consequence  of  the  complexity.  This  also 
was  new  and  unlike  anything  that  had  formerly  existed  in  nature. 
Memory,  the  name  we  apply  to  the  power  of  making  mental 
acquirements,  of  growing  mentally  in  response  to  the  stimulus  of 
experience,  is  strictly  the  counterpart,  the  homologue,  of  the  power 
of  growing  physically  in  response  to  the  stimulus  of  use.  Indeed 
the  physical  power  may  be  termed  the  physical  memory,  while  the 
additions  made  to  our  bodies  through  it  are  the  homologues  of 
the  mental  growth,  the  stored  experience,  which  results  from  the 
exercise  of  the  mental  power.  In  both  cases,  as  we  have  seen, 
the  powers  are  '  innate '  or  nutritional  characters  found  only  in  the 
higher  animals,  and  in  their  greatest  developments  only  in  the 
highest.  Probably  they  originated  about  the  same  time,  and 
perhaps  in  the  same  type  of  living  beings. 

652.  Memory  is  the  power  of  making  mental  acquirements. 
Though  we  speak  of  our  recollections  of  past  events  as  memories, 
yet,  strictly  speaking,  these  acquirements  are  only  the  contents  of 
memory.  The  memory  itself  is  purely  innate,  and  is  not  increased 
by  experience,  though  the  volume  of  its  contents  is  so  increased. 
In  other  words,  the  power  of  learning  does  not  increase  from  birth 
forwards.  On  the  contrary,  it  diminishes.  A  young  infant,  for 
example,  is  more  capable  of  learning  than  an  older  person.  At 
birth,  the  mind  of  a  child,  except  for  sensations  and  a  few  instincts, 
is  blank.  Sights  and  sounds  and  other  feelings  convey  no  mean- 
ings to  it.  But  soon,  so  great  is  its  power  of  learning,  the  messages 
sent  by  the  organs  of  sense  are  understood.  In  a  few  weeks  it 
evolves  order  out  of  chaos,  and  comprehends  to  a  wonderful  degree 
the  world  around  it.  It  learns  to  co-ordinate  its  muscles,  and  in  a 
year  or  two  is  able  to  walk  and  speak  a  language,  and  do  a  vast 
deal  besides.  In  these  early  years,  the  years  of  man's  greatest 
mental  activity,  he  makes  his  most  valuable  and  fundamentally 
indispensable  physical  and  mental  acquirements.  But,  as  he 
becomes  more  and  more  completely  equipped  for  the  battle  of  life, 
his  powers  of  adding  to  the  store  slowly  decline.  In  adult  life  the 
gains  tend  to  be  balanced  by  the  losses.  In  old  age  the  mental, 


THE  CHILD'S  POWER  OF  LEARNING  395 

like  the  physical  losses,  exceed  the  gains.  Compare  the  perfection 
with  which  the  young  are  able  to  acquire  the  manners  of  a  society, 
and  every  accent,  inflection,  and  intonation  of  one  or  more 
languages,  with  the  imperfections  displayed  when  the  task  is  under- 
taken later,  and  the  superiority  of  the  youthful  powers  of  learning 
at  once  becomes  manifest.  There  are  many  things  which  we  are 
better  able  to  acquire  later  in  life  than  during  infancy;  for  example, 
mathematical  knowledge;  not,  however,  because  our  powers  of 
learning  are  greater,  but  only  because  we  are  able  to  build  on 
acquirements  previously  made.  Similarly,  while  a  child,  whose 
power  of  growing  physically  is  so  great,  cannot  in  a  few  weeks  or 
months  acquire  the  muscles  of  an  athlete,  a  man,  whose  develop- 
ment is  sufficiently  advanced,  but  who  is  less  capable  of  growth, 
may  do  so.  It  is  sometimes  said  that  an  infant  cannot  make  the 
physical  and  mental  acquirements  which  are  possible  to  a  child, 
nor  a  child  those  which  are  possible  to  an  adult,  merely  because  the 
anatomical  developments  of  brain  and  body  are  not  yet  sufficiently 
advanced.  This  statement  is  true,  of  course.  But  the  hypothesis 
it  is  meant  to  support — that  the  developments  which  render 
possible  various  actions  arise  independently  of,  not  in  consequence 
of,  previous  use — is  not  true.  The  question  is  easily  tested. 
Would  a  child  who  had  not  previously  learned  to  walk  or  do 
simple  arithmetical  problems,  develop  body  and  mind  sufficiently 
to  enable  it  to  play  cricket  and  learn  the  calculus  ? 

653.  As  we  add  to  our  mental  stores  our  minds  grow,  but  not 
our  memories,  not  our  powers  of  learning.     So,  also,  as  we  add  to 
our  store  of  physical  acquirements  our  bodies  grow,  but  not  our 
power  of  growing  physically.     Systems  for  improving  the  memory, 
of  which  many  have  been  invented,  do  not  improve  it  in  the  least. 
They  merely  direct  the  attention  more  strongly   to  facts  which 
are  considered  worthy  of  remembrance,  and,  by  making  them  form 
mental  associations  with  familiar  objects  or  common  happenings, 
seek  to  secure  their  recall  to  mind.1 

654.  Our  minds  are  as  busy  storing  experiences  when  we  are 
merely  *  passing  the  time '  as  when  we  consciously  endeavour  to 
memorize  ;  but  in  the  former  case  there  is  so  much  that  is  almost 
identical  with  other  experiences  that  it  cannot  be  recalled  in  detail. 
On  that  account  we  can  recall  but  few  of  the  common,  the  unremark- 

1  See  James,  Principles  of  Psychology,  vol.  i.  pp.  659,  et  seq.  "  No  amount 
of  culture  would  seem  capable  of  modifying  a  man's  general  retentiveness  .  .  . 
all  improvement  of  memory  consists,  then,  in  the  improvement  of  one's  habitual 
methods  of  recalling  facts." 


396  THE  EVOLUTION  OF  MEMORY 

able  happenings  of  our  daily  lives.  So,  also,  if  we  saw  a  thousand 
sheep  jump  in  succession  over  a  gate,  we  could  recall,  not  the 
action  of  every  sheep,  but  in  the  main  only  a  general  notion. 
The  ultimate  result  is,  that  our  minds  are  not  burdened  with  a 
mass  of  unnecessary  details,  but  store  only  what  is  likely  to  be 
useful.  Our  general  impressions  are  concentrated,  condensed 
recollections.  Concentrated  memories  also,  as  we  shall  see 
presently,  are  all  our  acquired  dexterities  in  thinking  and  acting. 
Moreover,  apart  from  the  concentration  which  occurs  in  the 
formation  of  general  impressions,  much  that  is  seemingly  lost  and 
forgotten  is  none  the  less  stored,  and  waits  ready  to  be  dragged 
into  the  conscious  mind  by  some  associated  fact  or  idea.  Thus 
when  walking  down  the  street  we  may  see  a  face  which  is  recorded 
but  not  recalled  unless  a  second  meeting  awakens  the  memory. 

655.  Every  animal  species  is  fitted  by  its  structures  and  their 
associated   faculties   to  its  particular  place  in   nature.     In  some 
cases  it  holds  its  own  largely  through  the  great  evolution  of  some 
one  structure  or  group  of  structures  in  co-adaptation  with  which 
the  whole  mind  and  body  is  modified.     Thus  the  bat  is  especially 
distinguished  by  the  great  development  of  its  fingers  and  of  the 
web  between  them,  and  the  elephant  by  its  trunk.     The  principal 
distinguishing  physical  peculiarity  of  man  is  the  enormous  relative 
size  of  that  upper  part  of  the  vertebrate  brain  which  is  termed  the 
cerebrum,  and  which  we  have  every  reason  to  believe  constitutes 
his  organ  of  memory  and  thought,  and  of  all  the  mental  processes 
and  physical  co-ordinations  that  depend  on  them.     The  cerebrum, 
especially  the  human  cerebrum,  is  one  of  those  organs  which,  after 
birth,  develop  under  the  influence  of  use,  its  growth  being  cor- 
related to  the  growth  of  the  mind  under  the  stimulus  of  experience. 
In   evidence  of  this  is  the   fact,  that  if  one  hemisphere  of  the 
cerebrum  be  injured,  as  by  disease,  the  other  tends  to  hypertrophy 
under  the  stimulus  of  increased  use. 

656.  Associated  in  a  special  way  with  man's  great  brain  are 
his  organs  of  speech  and  manipulation.     These  three  structures, 
the    brain,    the    vocal    apparatus,    and    the    hand,    undoubtedly 
underwent  concurrent  evolution  by  the  constant  survival,  during 
what  must  have  been  a  period  of  intense    competition,  of  those 
individuals  who  were  *  naturally '  (i.e.  innately)  the  best  capable 
of  receiving  and  storing  experience,  of  using  it  for  the  intelligent 
manipulation  of  objects,  and  of  communicating  it  to  their  fellows 
and    descendants   through   the   medium   of    speech.      Even  the 
highest  of  the  lower  animals  are  able  to  learn  from  one  another 


TRADITIONAL  KNOWLEDGE  397 

only  by  example,  or  through  such  very  elementary  verbal  signs 
as  calls,  growls,  or  cries  of  alarm,  which  express  no  more  than 
simple  emotions.  Therefore  their  traditional  knowledge  is  as 
nothing  compared  to  that  of  man,  who,  by  means  of  articulated 
speech,  indicates  not  only  sense-impressions  and  emotions,  but 
also  complex  items  of  knowledge  and  processes  of  thought  which 
have  been  garnered,  elaborated,  and  systematized  during  tens  of 
thousands  of  years  by  millions  of  predecessors.  Without  speech 
or  some  such  method  of  communicating  abstruse  information,  his 
great  brain  and  its  special  functions  would  be  useless.  Knowledge 
and  powers  of  thought  are  of  no  avail,  unless  they  can  be  trans- 
lated into  action,  and  for  this  the  hands  are  necessary.  To  set 
free  the  forelimbs,  which  had  hitherto  been  organs  of  locomotion, 
for  their  new  function  of  manipulation,  man  gradually  became  a 
biped,  and  assumed  the  erect  attitude — not,  of  course,  by  any 
conscious  effort,  but  by  the  constant  survival  of  the  fittest,  those 
best  structurally  adapted  to  walk  erect. 

657.  Savage  man  differs  from  lower  animals  mainly  in  that 
he  has,  relatively  to  his  size,  a  larger  brain,  a  more  capacious 
memory,  and  greater  powers  of  using  its  contents  and  communi- 
cating them  to  others  of  his  species.  Modern  man  differs  from 
ancient  man  because  he  is  heir  to  a  greater  accumulation  of 
traditionally  transmitted  experience.  Civilized  man  differs  from 
the  savage  chiefly  in  that  he  has  invented  and  more  or  less 
perfected  certain  artificial  aids  to  memory,  thought,  and  speech 
— written  symbols  by  means  of  which  he  is  able  to  store  in 
an  available  form  information  immensely  more  abstruse  and 
voluminous  than  would  otherwise  be  possible.  His  books  are 
artificial  memories  and  vehicles  of  communication  of  unlimited 
capacity  and  unerring  accuracy.  Moreover,  by  means  of  these 
symbols  he  is  able,  as  in  the  mathematics,  to  perform  feats  of 
thinking  quite  beyond  the  powers  of  his  unaided  mind,  just 
as  by  means  of  mechanical  contrivances,  he  is  able  to  perform 
physical  feats  beyond  the  unaided  powers  of  his  body.  Obviously, 
the  mental  change  which  occurred  when  savage  races  achieved 
civilization  did  not  necessarily  imply  germinal  alteration.  But, 
because  each  generation  communicated  its  growing  traditions  to 
the  next,  it  so  exactly  mimicked  evolution  that  innumerable 
writers  have  been  deceived.  The  belief  is  almost  universal  that 
the  savage  differs  innately  in  mind  from  the  civilized  man.1  He 

1  Dr  Alfred  Russel  Wallace  is  a  rare  exception.      See  his  very  interesting 
article  on  Evolution  and  Character  in  the  Fortnightly  Review,  Jan.  1908. 


398  THE  EVOLUTION  OF  MEMORY 

may  differ,  and  very  possibly  does  differ,  to  some  extent,  but  the 
evidence  on  which  an  opinion  may  be  founded  is  lacking. 

658.  To  memory,  then,  is  due  the  advance  of  the  savage  beyond 
the  lower  animal ;  to  tradition,  the  child  of  memory,  the  advance 
of  modern  man  beyond  ancient  man ;  to  facts  and  thoughts  stored 
in  books  the  advance  of  civilized  man  beyond  the  savage.     To 
written  symbols  also  are  due   his  vast  potentialities    for   future 
advance.     In  the  past  of  the  earth  the  brute,  the  mammoth,  the 
bear,  the  tiger,  the  horse,  the  ox,  and   the  sheep,  became  ever 
more  and  more  helpless  in  the  presence  of  a  knowledge  and  an 
ingenuity,  the  outcome  of  organized  knowledge,  which  gathered 
direfully  with  the  rolling  years,  and  which,  though  accumulating 
for  ages,  were  yet  comparatively  new  things  in  this  enormously 
old  world. 

659.  The  lower  animals  in  proportion  as  they  lack  memory — 
in  proportion  as  they  are  incapable  of  profiting  from  experience, 
but    develop   more   or    less   exclusively   under    the   stimulus   of 
nutrition — move  in  a  narrow,  instinctive  groove.     Their  mental 
traits  are  'innate  and  inherited,'  and,  therefore,  every  individual 
follows  nearly  exactly  in  the  footsteps  of  its  predecessors.     Since 
they  cannot  learn  they  cannot  adapt  themselves  to  circumstances. 
Removed  from  the  ancestral  environment,  they  perish.     Cast  in  a 
rigid  inexpansive  mould,  they  resemble  one  another  of  the  same 
species  as  much  mentally  as  physically.     It  is  different  with  man. 
He  is  pre-eminently  the  educable,  the  reflective,  the  adaptable 
animal — the  animal  who  develops  mentally  under  the  stimulus  of 
use.     Since  men  can  learn,  and  since  the  experiences  of  no  two 
men  are  quite  similar,  they  differ  in  knowledge,  ideas,  aspirations, 
modes  of  thought,  and  motives  for  action.     Therefore  none  are 
very  closely  alike  mentally.     The  child  does  not  follow  exactly  in 
the  footsteps  of  his  parent.     So  great  is  human  educability  (i.e. 
adaptability)  that  though  the  mind  of  the  savage  differs  immensely 
in  all  except  instincts  and  powers  of  learning  from  that  of  the 
civilized  man,  yet  if  the  child  of  the  latter  were  trained  from  birth 
by  the  former  he  could  not  be  other  than  a  savage.     Indeed  the 
offspring  of  civilized  parents  captured  by  savages  (e.g.  American 
Indians)  have  actually  developed    into  utter   savages.      On    the 
other  hand,  some  savages,  for  example  the  Maoris  of  New  Zealand, 
have  passed  in  a  single  generation  from  barbarism  to  civilization. 
The  Maoris,  as  I  judge  from  personal  experience,  are  not  innately 
inferior  mentally  to  Europeans.     They  are  unable  to  compete  with 
the  intrusive  whites  only  because  they  are  more  susceptible  to 


CONSCIOUS  AND  UNCONSCIOUS  MEMORY          399 

imported  diseases.  The  average  individual  amongst  us,  and 
doubtless  amongst  the  Maoris,  may  be  trained  to  fill  the  role  of  a 
beggar  or  a  king,  a  scientist  or  a  monk,  a  thief  or  legislator.  He 
is  so  intelligent,  so  adaptable  that  he  is  able  to  dwell  in  the  tropics 
or  in  the  Arctic,  in  the  city  or  the  wild,  on  land  or  on  sea.  Memory, 
knowledge,  intelligence,  reason,  adaptability,  are  all  links  in  a 
single  chain  of  efficiency. 

660.  Memory  is  of  two  sorts,  conscious  and  unconscious.  The 
conscious  memory  contains  experiences  which  can  be  ^-collected, 
such  as  scenes  we  have  beheld,  or  the  words  of  a  language.  The 
unconscious  memory  contains  impressions  which  cannot  be  recalled 
to  mind,  but  which  are  none  the  less  important.  Indeed,  many  of 
its  contents  were  never  present  in  consciousness  in  the  sense  that 
a  sight,  an  emotion,  or  an  idea  is  present.  Thus  we  learn  to  use 
our  legs  in  walking,  a  process  that  involves  a  precise  but  unconscious 
adjustment  of  the  actions  of  numerous  muscles,  the  very  existences 
of  which  are  unknown  except  to  the  anatomist.  In  a  sense,  therefore, 
we  know  as  little  about  walking  as  any  insect.  All  our  acquired 
dexterities,  both  in  thinking  and  acting,  belong  to  this  category. 
They  are  mental  acquirements  stored  by  the  unconscious  memory. 
Thus  we  learn  to  reason  ;  but,  though  we  recall  some  of  the  times 
and  lessons  by  which  we  learned  to  think  well,  and  though  results 
may  make  us  conscious  of  a  growing  facility  in  reasoning,  yet  the 
facility  itself,  like  dexterity  in  walking,  is  a  thing  that  is  outside 
our  consciousness.  So  also,  to  some  extent  at  least  and  especially 
in  youth,  we  unconsciously  imitate  our  fellows,  adopting  in  great 
measure  their  mental  tones  and  attitudes  without  knowing  how  or 
when  we  were  influenced.  Many  experiences,  too,  once  capable  of 
being  distinctly  recalled,  are  added  to  that  hidden  store,  and, 
though  apparently  lost,  remain  potent  for  good  or  evil.  Our  minds 
are  like  floating  icebergs,  of  which  the  visible  part  is  but  a  fraction 
of  the  whole,  and  which  are  moved  by  deep  currents  in  a  seemingly 
unaccountable  way.1 

1 1  speak  of  the  '  unconscious  memory.'  The  expression  is  in  common  use,  and 
is  convenient.  But,  properly  speaking,  memory  is  the  faculty  for  storing  and 
recalling  to  consciousness  feelings  that  have  been  there  before.  An  unconscious 
memory,  therefore,  is  a  contradiction  in  terms.  Probably  what  we  call  uncon- 
scious memory  is  nothing  other  than  a  growth  in  efficiency,  or  in  size,  or  in  com- 
plexity, or  in  all  three,  of  brain ;  a  growth  which  enables  that  organ  to  perform 
work  which  till  then  it  was  incapable  of  performing,  or  which  it  was  incapable  of 
performing  as  easily  or  as  well.  In  physiological  and  psychological  writings  this 
cerebral  change  is  usually  spoken  of  as  an  "  opening  up  of  paths  "  in  the  brain. 
If  by  that  is  meant  a  building-up  in  the  brain  analogous  to  that  building  which 
occurs  when  an  addition  is  made  to  our  means  of  telephonic  communication,  the 


400  THE  EVOLUTION  OF  MEMORY 

66 1.  We  learn  to  do  new  things,  acquire  new  knowledge,  and 
think  new  thoughts  with  toil.     But  practice  confers  facility.     In 
the  end  we  know  or  perform  with  ease  that  which  was  acquired 
with  difficulty.     We  cannot  unlearn,  however,  as  we  have  learned 
by  an  act  of  will.     The  facility  (the  brain  change)  lingers,  and,  as 
a  consequence,  since  we  tend  to  lose  our  powers  of  making  new 
acquirements,   our   action   and   thoughts,  our   mental   tones    and 
attitudes,   our    whole    outlook    on    life,    becomes    more    or   less 
'automatic'   or   stereotyped.1     In  other  words,  our  acquirements 
come  at  last  to   resemble  reflexes  and  instincts.     Not  only  do 
they  take  the  place  of  those  reflexes  and  instincts  which  retro- 
gressed when  memory  was  evolved,  but  they  are  infinitely  more 
numerous.     So  like  are  they  to  reflexes  and  instincts  that  they  are 
often  so  misnamed.     Thus  psychologists  usually  place  automatic 
actions  in  the  reflex  category.     As  a  fact,  reflexes  and  automatic 
actions  are  as  poles  apart ;  but  of  this  more  presently.2 

662.  Again  we  often  apply  the  term  '  instinctive '  to  emotions 
and    'physical5    dexterities    which    have    been    acquired.      For 
example,  deceived  by  the  quickness  and  readiness  of  the  act,  we 
speak  of  such  actions  as  that  of  a  boy  when  he  dodges  a  blow  as 
instinctive.     But  the  boy  has  learned  to  dodge,  and  would  learn  to 
dodge  still  better  and  quicker  if  he  went  into  training  for  the  prize 
ring.     When  untaught  by  experience,  he  can  no  more  dodge  a  blow 
than  he  can  solve  a  problem  in  quadratics.     His  action  is  intrinsi- 
cally different  from  that  of  a  house-fly,  which  learns  nothing  from 
experience,  and  dodges  as  well  at  the  first  attempt  as  at  the  last. 
It  is  the  mode  of  origin,  not  the  quickness,  readiness,  or  facility  in 
performance  which  constitutes  the  difference  between  reflex  and 

expression  may  pass,  though  it  is  apt  to  mislead.  But,  if  by  it  be  meant  that 
'  channels  '  are  somehow  made  in  the  brain  analogous  to  those  which  water  wears 
on  or  under  the  ground,  the  expression  is,  probably,  not  only  misleading,  but 
wrong  in  every  sense.  There  is  nothing  to  justify  it  except  an  impossible  analogy. 
It  is  admitted  that  mental  happenings  are  correlated  to  cerebral  happenings.  If 
mental  growth  occurs,  for  example  increased  thinking  capacity,  we  have  every 
reason  to  believe  that  this  growth  is  correlated  with  actual  cerebral  growth 
analogous  to  muscular  growth — though  possibly  this  growth  may  often  imply 
little  or  no  increase  in  the  size  of  the  brain,  but  only  an  adjustment  which 
increases  its  working  power. 

1  It  would  be  well  for  the  avoidance  of  subsequent  confusion  if  the  reader 
carefully  noted  the  meaning  here  given  to  the  word  '  automatic.'  An  automatic 
action  is  one  which  we  have  learned  to  perform,  but  which,  through  practice,  has 
become  so  easy  of  performance  that,  like  a  reflex  action,  it  is  done,  apparently, 
without  mental  effort.  It  is  sharply  distinguished  from  a  reflex  action  in  that  it 
is  a  product  of  individual  experience. 

8  See  §§  676  et  seq. 


IMITATION  REFLEXES  AND  INSTINCTS  401 

instinctive  actions  on  the  one  hand,  and,  on  the  other,  actions  which 
are  often  termed  automatic,  or  intelligent,  or  rational,  but  which  as 
a  class  are  best  distinguished  as  actions  the  performance  of  which 
depends  on  stored  experience,  on  memory.  So  alike  are  our 
acquired  emotions  and  dexterities  to  their  '  innate '  counterparts 
that  a  being  from  another  planet,  who  for  the  first  time  saw  a  man 
walking,  cycling,  or  reading,  could  not  distinguish  the  nature  of 
these  acquirements  from  such  instinctive  actions  as  the  running, 
flying,  or  building,  of  an  insect.  The  patriotic  emotion  of  a 
Spartan  or  a  Japanese  differs  from  that  of  a  bee  or  an  ant  merely 
in  its  mode  of  origin.  Were  the  religious  fervour  of  a  Salva- 
tionist or  a  dervish,  or  the  hatred  of  religion  which  characterises 
the  atheist,  innate,  it  would  be  an  instinct.  But  these  emotions, 
like  many  of  our  '  physical '  dexterities,  are  obvious  acquirements. 
TktSy  then,  is  the  main  distinction  between  man  and  the  low 
animal ; — the  emotions  and  (apart  from  the  reflexes)  the  dexterities 
of  the  mart  are  mainly  HABITUAL  or  'acquired ;'  those  of  the  low 
animal  are  wholly  or  almost  wholly  instinctive  or  * inborn'  The 
former  develop  under  the  stimulus  of  use ;  the  latter  under  that 
of  nutriment. 

663.  A  principal  function  of  our  faculty  of  making  mental 
acquirements,  of  our  conscious  and  unconscious  memories,  is  to 
supply  us  with  those  automatic  and  stereotyped  ways  of  thinking 
and  acting  which  are  our  substitutes  for  numerous  reflexes  and 
instincts.  Our  conscious  memories  supply  us  in  part  with  our 
stereotyped  mental  attitudes — desires,  beliefs,  aspirations,  habitual 
ways  of  thinking,  and  so  forth.  Our  unconscious  memories,  not 
only  aid  in  building  up  our  mental  attitudes,  but  give  us  our  stereo- 
typed ways  of  acting — those  automatic  ways  of  acting  (e.g.  walking, 
reading,  cycling,  etc.),  we  have  just  considered.  At  the  same  time 
our  physical  'memories'  (our  powers  of  making  physical  acquire- 
ments) enable  us  to  develop,  in  perfect  co-adaptation  with  our 
mental  acquirements,  our  bodily  parts,  our  brains,  limbs,  lungs, 
heart,  and  the  like.  As  we  grow  older  our  imitation  reflexes  and 
instincts  increase  in  number  and  importance ;  they  form  a  larger 
and  larger  portion  of  our  total  reaction  to  the  environment.  They 
equip  us  for  the  battle  of  life  with  a  thousand  faculties  for  acting 
readily^  quickly^  and  easily.  In  the  aggregate  they  are  immensely 
superior  to  real  instincts  and  reflexes  for  they  render  the  individual 
adaptable  ;  they  enable  him  to  grow  into  fitness  to  the  particular 
environment  in  which  he  is  reared ;  and,  even  if  he  changes  it,  to 
grow  to  fit  the  new  one.  Whether  he  be  artist  or  sailor,  beggar 
26 


402  THE  EVOLUTION  OF  MEMORY 

or  king,  he  develops  just  such  dexterities  in  thought  and  action  as 
are  necessary  to  him,  but  is  burdened  with  no  more.  Our  human 
memory ',  our  power  of  growing  mentally  in  response  to  the  stimulus 
of  use  and  experience  is  a  device  by  means  of  which  nature  has 
surmounted  the  difficulty  of  evolving  an  untold  number  of  reflexes 
and  instincts.  Each  real  reflex  and  instinct  demands  for  its 
evolution  and  maintenance  a  separate  process  of  selection.  For 
example,  the  reflexes  of  the  heart  and  the  bowels,  and  the  instincts 
of  hunger  and  sexual  love  are  entirely  separate  things  not  evolved 
by  the  same  process  of  selection  and  not  equally  well  developed 
in  every  individual.  If  the  individual  is  defective  in  any  important 
reflex  or  instinct,  he  leaves  no  offspring.  Therefore  nature  must 
maintain  all.  When  they  are  very  numerous,  individuals  defective 
in  one  or  another  are  so  many  that  the  death-rate  tends  to  exceed 
the  birth-rate.  Therefore  there  is  a  limit  to  their  number.  In 
other  words  there  is  a  limit  to  the  complexity  of  the  individual  in 
innate  characters,  and  therefore  a  limit  to  the  number  of  innate 
reactions  he  is  able  to  make  to  the  environment.  On  the  other 
hand  in  memory  nature  evolves  and  maintains  only  one  thing. 
But  that  one  thing,  as  I  say,  is  capable  of  supplying  any  number 
of  emotions  and  automatic  reactions  which  answer  precisely  the 
same  purpose  as  innate  reactions. 

664.  It  is   a  principal  business  of  our  lives  to  acquire  these 
dexterities  in  performance  (e.g.  walking),  these  imitation  reflexes 
(e.g.  quick  withdrawal  from  a  cause  of  pain)  and  these  imitation 
instincts  (e.g.  patriotism).     But,  though  a  great  advantage  is  gained 
when  the  acquirements  are  made,  one  almost  as  great  is  lost.     We 
then  think  and  act  more  quickly  in  familiar  situations.     When  the 
adult  stage  is  reached  we  are  by  virtue  of  them  as  fit  or  more  fit 
than  an  insect  to  face  the  battle  of  life.     But  each  important  ac- 
quirement is  written,  as  it  were,  in  indelible  ink  on  the  sheet  of  the 
mind.     This   matters  comparatively  little   in   the  case   of  those 
automatic    actions  which  take  the  place  of  reflexes.     They  are 
almost  always  useful,  as  for  example,  the  automatic  co-ordinations 
of  our  muscles  by  means  of  which  we  walk,  speak,  cycle,  swim,  knit, 
or  dodge  blows.     But  our  bad  as  well  as  our  good  acquirements 
are  imitation  instincts.     Once  acquired,  they  tend  perpetually  to 
pull  us  down.     Moreover,  as  we  grow  older,  we  tend  to  lose  our 
splendid  human  capacity  for  learning.     Old  habits,  good  or  bad, 
persist ;  new  habits  cannot  easily  be  acquired. 

665.  In   addition    to    the    acquired    dexterities   and    mental 
attitudes  which   depend   on   records  unconsciously  retained,  our 


SKILL  IN  THINKING  403 

memories  supply  us  with  a  vast  fund  of  facts,  ideas,  emotions,  and 
the  like,  which  may  be  more  or  less  vividly  recalled  to  mind  and 
which,  therefore,  afford  the  materials  for  such  mental  processes  as 
association,  comparison,  and  discrimination  —  in  brief  with  the 
materials  of  allthatis  comprised  under  the  term  thought.  Byappeal- 
ing  to  our  conscious  memories  we  are  able  to  note  sequences  of 
events  in  the  past  and  deduce  necessary  truths  and  so  to  fore- 
see to  a  very  useful  extent  the  sequences  of  events  in  the  future, 
and  in  this  way  make  provision  for  coming  events  and  dangers.  By 
virtue  of  the  intellectual  powers  thus  conferred  we  are  rational 
beings  in  the  strict  sense  of  the  word.  Unlike  the  purely  instinctive 
animal  which  is  impelled  merely  by  emotion,  we  guide  our  more 
complex  and  less  habitual  actions  by  thought,  by  intelligence  and 
reason.  But  though  the  whole  domain  of  the  intellect  pertains  to 
the  conscious  memory,  yet  we  are  able  to  labour  usefully  in  it  only 
by  virtue  of  powers  conferred  by  the  unconscious  recorder  of  our 
experiences.  We  learn  to  think,  to  reason  just  as  certainly  as  we 
learn  '  physical  dexterities,'  but,  as  in  the  case  of  the  latter,  the 
springs  of  our  '  mental '  dexterities  cannot  be  recalled  to  mind  in 
the  sense  that  an  event  or  a  fact  may  be  recalled.  That  is,  though 
we  may  remember  that  we  are  skilful  in  thinking,  and  though  we 
may  call  to  mind  the  ways  in  which  we  acquired  the  skill  and  the 
results  we  obtain  by  the  exercise  of  it,  yet  the  skill  itself  depends 
on  concentrated  experiences  which  cannot  be  recalled  to  mind  any 
more  than  those  on  which  skill  in  walking  depends.  The  skill  is 
useful,  but  the  power  of  picturing  it  in  mind  would  be  of  no 
practical  utility ;  and  therefore  nature  does  not  bestow  it. 

666.  An  instinct  impels  us  to  sport  with  our  limbs  and  so 
supply  them  with  the  stimulus  necessary  for  growth  and  our  minds 
with  the  practice  which  confers  dexterity  in  using  the  limbs.  This 
growth  of '  physical '  dexterity  is,  as  we  see,  really  a  mental  growth. 
So  also,  an  even  more  imperious  instinct  impels  us  to  sport  with  our 
thoughts.  From  birth  forwards  we  think  perpetually  and  cannot 
help  doing  so.  Fresh  experiences  recall  antecedent  experi- 
ences with  which  they  are  compared,  and,  these  again  call  up 
yet  other  experiences.  In  our  idlest  moments  we  are  busy 
thinking.  In  this  way  we  learn  dexterity  in  thinking,  and  this 
acquired  dexterity  is  an  essential  part  of  intelligence  and  reason. 
Obviously,  therefore,  reason  is  not,  as  all  psychologists  imply,  an 
*  innate '  character  like  memory.  It  is  learned  just  as  surely  as 
reading  and  walking  are  learned.  No  child  is  born  capable 
of  reasoning,  and  much  of  our  school-room  education  is  a 


404  THE  EVOLUTION  OF  MEMORY 

formal   endeavour   to   develop   the   faculty  by  means   of  special 
exercises. 

667.  The  range  of  thought  possessed  by  any  species  is  always 
proportionate  to  the  greatness  of  the  conscious  memory,  which 
records  not  only  items  presented    by  the  senses,  but   also  those 
acquired   through    the   imagination    and    intelligence.      On   this 
account  the  dog  has  a  greater  range  than  the  cat,  and  man  than 
the  dog.     Man's  unique  intellectual  powers  depend  wholly  on  his 
vast  and  capacious  memory  by  means  of  which  he  acquires  both 
the  materials  (facts  and  ideas)  and  the  methods  (association,  dis- 
crimination,  and   the   like)   of  thought — materials   and    methods 
which   render   him   intelligent,   rational,   'self-conscious,'  capable 
of  'conceptual  thought'    and   of  'apprehending  universals,'  and 
abstract  ideas  such  as  those  of  right  and  wrong,  and  of  performing 
feats  of  thinking  as  in  mathematics,  philosophy,  and  science,  or  of 
imagination  as  in  music,  poetry,  and  fiction,  or  of  ingenuity  as  in 
engineering  and  warfare,  or  of  becoming  devout  or  patriotic,  and 
so  forth.     The  fact  that  he  alone,  of  all  animals,  is  capable  of  these 
mental   operations   has  caused  many  writers  to   declare  that  an 
impassable  gulf  separates  him  from  the  rest  of  living  nature.     But 
plainly  there  is  no  impassable  gulf.     None  of  the  traits  mentioned 
are  'inborn'  or  special  products  of  evolution  or  creation.     The 
infant  possesses  none  and  can  possess  none  until  his  memory  is 
stored  with  the  materials  of  thought  and  he  has  learned  through 
imitation  and  practice  fit  methods  of  thinking.     He  differs  from 
lower  animals  only  in  that  his  memory  is  so  large  that  it  alone  is 
capable  of  being  stored  with  these  traits  amongst  many  others. 
That  which  has  been  created  by  evolution  is  his  huge  cerebrum, 
the  organ  of  memory,  the  thing  which  does  the  work  which  is 
memory,  reason,  and  all  the  rest  which  results  from  acquirement. 
Both  cerebrum  and  memory  are  found  in  lower  animals,  and  there 
is    no   greater   difficulty   in   conceiving   man's    mental   evolution 
through  the  continued  selection  of  mentally  superior  individuals 
(that  is,  of  individuals  who  are  mentally  superior  because  they  have 
a  superior  quality  of  brain)  than  of  conceiving  the  evolution  of  the 
elephant's   trunk,   the   bat's   wing,    or    any   other  structure   that 
especially  distinguishes  this  or  that  animal. 

668.  Not  only  may  memory  vary  as  a  whole,  but  it  may  vary 
in  particular  directions  in  different  individuals.     Thus,  while  one 
man  may  possess  exceptional  powers  of  acquiring  the  facts  and 
methods  of  mathematics  and  of  learning  to  use  his  knowledge  for 
purposes  of  fresh  discovery,  another  man  may  be  similarly  dis- 


MENTAL  EVOLUTION  405 

tinguished  with  respect  to  music,  literature,  engineering,  or  warfare. 
But  there  is  nothing  more  wonderful  in  this  than  in  the  fact  that 
some  part  of  a  structure  (e.g.  a  nose)  may  be  relatively  more 
developed  in  one  man  than  in  another.  Men  often  differ  very 
greatly  in  mental  capacity,  in  innate  power  of  making  this  or  that 
acquirement,  and  doubtless  these  mental  differences  are  associated 
with  innate  cerebral  peculiarities,  and  tend,  therefore,  to  be  trans- 
mitted to  offspring;  but  it  must  be  borne  in  mind  that  mental 
differences  need  not  imply  correspondingly  great  cerebral 
differences.  When  we  attempt  to  estimate  the  latter  by  means  of 
the  former,  we  examine  them,  as  it  were,  through  a  magnifying 
glass.  The  amount  of  nervous  tissue  in  the  brains  of  ants  is  very 
small  and  the  differences  apparently  are  not  very  great,  yet  the 
species  differ  vastly  in  their  mental  characters.  Small  cerebral 
variations,  therefore,  may  imply  great  psychological  differences. 

669.  None  of  the  objections  by  which  it  was  sought  to  contro- 
vert the  doctrine  of  man's  mental  evolution  from  lowerltypes  could 
have  been  maintained  had  the  faculties  (mathematical,  devotional, 
musical,  and  the  like)  concerning  which  controversy  raged  been 
traced  to  their  true  source,  memory.     The  evolution  of  memory 
can  be  traced  with  the  same  degree  of  certainty  as  that  of  brain  or 
any  other  physical  structure  ;  but  I  think  I  am  right  in  saying 
that  hitherto  no  one  has  attempted  to  trace  it.     Its  importance 
has  not  been  realised  ;  and  only  very  scanty  space  is  devoted  to 
it  in  standard  works  on  evolution.     The  root  of  the  mischief  has 
lain  in  the  initial  failure  to  note  the  real  nature  of  the  difference 
between  '  inborn  '  and  *  acquired '  characters,  and  to  compare  the 
parts  they  have  played  in  evolution  and  development.     Acquire- 
ments, as   I   say,  have   been   regarded  as  transient  unimportant 
traits,  mere  accidents,  appearing  in  one  generation  and  disappear- 
ing in  the  next.     Some  attention,  indeed,  has  been  given  to  the 
faculty  of  growth  under  the  stimulus  of  injury  (regeneration),  but 
wonderfully  little  has  been  attracted  by  the  more  important  faculty 
of  growth  under  the  stimulus  of  use  and  experience.1 

670.  The  older  students  of  psychological  evolution  supposed 
that  memory  was  an  invariable  accompaniment  of  consciousness 
and  therefore  had  no  notion  that  it  was  a  late  and  high  product 
of  evolution.     Darwin,  as  far  as  I  have  been  able  to  ascertain, 
devotes  only  one  short  paragraph  to  it,  in  which  he  merely  relates 
three  incidents  which  tend  to  show  that   memory  is   present  in 
baboons,  dogs  and  cats.2     He  discusses,  however,  at  greater  length, 

1  See  §§  20,  et  seq.  a  Descent  of  Man,  p.  112. 


406  THE  EVOLUTION  OF  MEMORY 

imagination,  imitativeness,  and  reason,  all  of  which  depend  on 
memory  but  which  he  treats  as  independent  faculties.  Spencer 
regarded  instinct  as  compound  reflex  action  and  the  precursor  of 
intelligence,  which  he  thought  resulted  from  still  further  compound- 
ing. On  the  other  hand,  Lewes,  thinking,  like  Spencer,  in  terms  of 
the  Lamarckian  doctrine  but  arriving  at  an  opposite  conclusion, 
believed  that  the  intelligence  of  ancestors  becomes  the  instincts  of 
descendants.  That  is,  he  believed  that  mental  characters  which 
developed  in  the  ancestors  under  the  stimulus  of  experience  were 
*  inherited  '  by  descendants — i.e.  were  transmuted  into  characters 
that  developed  under  the  stimulus  of  nutriment.  He  failed  to 
note  the  fact,  fatal  to  his  hypothesis,  that  the  human  being,  the 
latest  product  of  evolution,  is  of  all  animals  the  most  equipped 
by  acquirements  and  the  least  by  instinct.  Richet  insisted  that 
"without  memory  no  conscious  sensation,  without  memory  no 
consciousness."  Romanes  declared :  "  The  most  fundamental 
principle  of  mental  operation  is  that  of  memory,  for  this  is  the 
conditio  sine  qua  non  of  all  mental  life."  l  "  The  power  of  learning 
by  individual  experience  is  therefore  the  criterion  of  mind."  He 
adds,  however,  "  But  it  is  not  an  absolute  or  infallible  criterion 
...  it  serves  to  fix  the  upper  limit  of  non-mental  action  more 
precisely  than  it  does  the  lower  limit  of  mental;  for  it  is  probable 
that  the  power  of  feeling  is  prior  to  that  of  consciously  learning."  2 
671.  When  a  particle  of  food  goes  the  wrong  way  I  cough. 
That  particular  reflex  is  quickly  abolished  by  chloroform  or  even 
a  local  anaesthetic.  Therefore  it  is  initiated  by  sensation,  by  mind. 
But  a  newly  born  infant  coughs  just  as  well  as  a  man.  Here  it 
has  nothing  to  learn.  The  act  is  quite  involuntary  and  has  no 
connection  with  memory.  But  it  is  highly  useful.  Therefore 

1  Mental  Evolution  in  Animals,  p.  35,  Romanes  proceeds  :  "  But  memory 
on  its  obverse  side,  or  the  side  of  physiology,  can  only  mean  that  a  nervous 
discharge,  having  once  taken  place  along  a  certain  route,  leaves  behind  it  a 
molecular  change,  more  or  less  permanent,  such  that  when  another  discharge 
afterwards  proceeds  along  the  same  route,  it  finds,  as  it  were,  the  footprints  of 
its  predecessor.  And  this,  as  we  have  seen,  is  no  more  than  we  find  to  be  the  case 
with  ganglionic  action  in  general."  This  notion  of  nervous  discharges  making 
paths  which  render  more  easy  the  passage  of  subsequent  similar  discharges  is 
found  in  almost  all  psychological  works,  and  furnishes  an  easy  but  as  we  have 
already  noted  a  fundamentally  deceptive  illustration.  In  low  animals,  in  which 
only  reflexes  and  instincts  occur,  nothing  is  added  to  the  mental  and  nervous 
equipment  by  experience.  In  higher  animals,  in  which  memory  is  present, 
the  stimulus  of  experience,  so  far  from  opening  a  path,  adds  a  growth. 
Hence  the  increase  in  volume  and  complexity  both  of  the  child's  mind  and  of 
his  brain. 

•^  Mental  Evolution  in  Animals,  p.  60. 


ROMANES  ON  MEMORY  407 

mind  without  memory  is  useful.  Romanes  himself,  by  means  of  a 
somewhat  cruel  experiment,  afforded  clear  evidence  of  the  lack  of 
memory  in  low  animals  and  the  usefulness  of  sensation  in  its 
absence.  "  I  am  more  surprised  with  my  failure  in  this  respect 
with  the  higher  Crustacea ;  for  although  I  have  tried  similar 
experiments  with  them  I  have  never  been  able  to  teach  them  the 
simplest  things.  Thus,  for  instance,  I  have  taken  a  hermit  crab 
and  put  it  into  a  tank  filled  with  water,  and  when  he  had  pro- 
truded his  head  from  the  shell  of  the  whelk  in  which  he  was 
residing,  I  gently  moved  towards  him  a  pair  of  open  scissors,  and 
gave  him  plenty  of  time  to  see  the  glistening  object.  Then, 
slowly  including  the  tip  of  one  of  his  tentacles  between  the  open 
blades,  I  suddenly  cut  off  the  tip.  Of  course  the  animal  immedi- 
ately drew  back  into  the  shell,  and  remained  there  for  a  consider- 
able time.  When  he  again  came  out  I  repeated  the  operation  as 
before,  and  so  on  for  a  great  number  of  times,  till  all  the  tentacles 
had  been  progressively  cut  away  little  by  little.  Yet  the  animal 
never  learnt  to  associate  the  appearance  of  the  scissors  with  the 
effect  which  always  followed  it,  and  so  never  drew  in  till  the  snip 
had  been  given.  Nevertheless,  that  memory  does  occur  among 
the  higher  Crustacea  is  proved  by  an  observation  quoted  in 
Animal  Intelligence  (p.  233),  concerning  a  lobster  mounting  guard 
upon  a  heap  of  shingle  beneath  which  it  had  previously  had  hidden 
some  food."  x 

672.  That  memory  is  absent  or  very  rudimentary  in  hermit 
crabs  is  proved  by  the  experiment.     That  the  action  of  the  lobster 
indicates  memory  is  not  so  certain.2     Though  named  in  the  margin, 
memory  had  no  place  in  Romanes'  famous  diagram  which  precedes 
his  works  on  Mental  Evolution  and  which  was  "intended  to  represent 
in  one  view  the  whole  course  of  mental  evolution,"  3  and  concerning 
which  he  wrote,  "  I  feel  confident  that  the  general  structure  of  our 
knowledge  concerning  the  evolution  of  mind  is  now  sufficiently 
coherent  to  render  it  highly  improbable  that  this  diagrammatic 
representation  of  it  will,  in  the  future,  be  altered  in  any  of  its  main 
features  by  any  advances  that  science  may  be  destined  to  make."  4 
In  his  list  of  the  products  of  intellectual  development  memory  is 
placed  before  the  primary  (i.e.  the  earliest)  instincts.5 

673.  Recent  writers  make  also  as  little  mention  of  memory  as 
a  factor  in  mental  evolution  as  Darwin.     The  mental  *  plasticity ' 

1  Op.  cit.,  pp.  122-3.  2  See  §  689. 

3  Mental  Evolution  in  Animals,  p.  63.  *  Op.  cit.,  pp.  63-4. 

6  See  Romanes'  diagram. 


408  THE  EVOLUTION  OF  MEMORY 

of  Baldwin,  Osborn,  and  Lloyd  Morgan l  is  of  course  memory,  but 
the  fact  is  nowhere  recognized.  Nor,  indeed,  is  the  importance  of 
the  so-called  plasticity  appreciated.  "  Professor  Morgan  here 
develops  (Chap.  XIV.,  Habit  and  Instinct)  a  suggestion  which  has 
been  put  forth  by  Professor  H.  F.  Osborn,  and  independently 
reached  by  the  present  writer,  as  Morgan  points  out,  namely,  that 
by  learning  intelligently  and  imitatively  to  do  the  things  which 
are  essential,  certain  animals  are  screened  from  the  operation  of 
Natural  Selection,  and  so  hand  on  their  capacities  to  future 
generations,  while  the  race  accumulates  further  congenital  varia- 
tions in  the  same  directions  (what  Morgan  calls  '  Coincident 
variations ').  Thus  evolution  takes  the  direction  marked  out  in 
the  first  instance  by  the  individual's  learning."  2  In  other  words, 
it  is  supposed  by  Baldwin,  Morgan,  and  Osborn  that  useful 
acquirements  may  enable  a  race  or  a  line  of  individuals  to  survive 
until  the  descendants  have  varied  in  such  a  way  that  the  useful 
traits  appear  in  them,  not  under  the  stimulus  of  experience,  but 
under  that  of  nutriment.3  In  this  way,  as  according  to  Lewes' 
theory  though  not  as  he  supposed  by  the  transmission  of  acquire- 
ments, that  which  was  intelligent  in  ancestors  becomes  instinctive 
in  descendants.  For  example,  if  learning  to  swim  or  to  speak  a 
language  enabled  ancestors  to  survive,  it  is  supposed  the  descendants 
may  vary  so  as  to  swim  or  speak  instinctively.  That  is,  unthinking 
impulse  is  supposed  to  be  substituted  in  descendants  for  learning, 
thought,  intelligence,  and  reason  in  ancestors.  This  theory,  of 
course,  affords  an  instance  of  the  prevalent  biological  obsession 
that  nutritional  characters  are  more  important,  more  innate,  more 
a  possession  of  the  species  than  characters  which  develop  under 
the  stimulus  of  use  and  experience — the  latter  being  regarded  as 
mere  accidents  limited  to  the  individual  and  not  like  nutritional 
characters,  part  of  the  heritage  of  the  race.  The  whole  course  of 
the  evolution  of  the  higher  animals  demonstrates  the  erroneousness 
of  this  opinion.  So  far  from  the  '  innate  '  replacing  the  '  acquired,' 
the  contrary  is  the  invariable  rule.  For  example,  in  man  the 
highest  and  the  latest  product  of  evolution,  that  which  is  *  inborn ' 
is  at  its  minimum,  while  that  which  is  *  acquired  '  is  at  its  maximum. 
It  is  not  realized  by  the  writers  mentioned  that  to  the  animals  that 
have  the  power  of  making  acquirements,  these  characters  are 

1  See,  for  example,  Development  and  Evolution,  by  James  Mark  Baldwin  (The 
Macmillan  Company),  and  y4m'wa£  Behaviour,  byC.  Lloyd  Morgan,  p.  172  (Arnold). 
Neither  of  these  authors  mention  memory.  At  any  rate  I  can  find  no  mention, 
and  the  word  does  not  occur  in  their  indices. 

8  Development  and  Evolution,  pp.  390-1.  3  See  §  114. 


MENDELIANS  AND  BIOMETRICIANS  409 

infinitely  more  useful  than  similar  '  innate '  characters  could  pos- 
sibly be.  They  render  the  individual  adaptable.  I  do  not  think 
I  overstate  the  case  when  I  insist  that,  until  this  truth  be  grasped, 
all  biological  speculation  concerning  the  evolution  of  the  higher 
animals  must  be,  in  great  measure,  futile. 

674.  Very  recent  biological  work  has  been  mainly  Mendelian 
or  biometric.      Memory  has  been  discussed  by  neither  the  one 
school  nor  the  other.     Mendelian  experiments  could,  at  most,  tell 
us  nothing  more  than  whether  the  reproduction  of  memory  is  or 
is  not  alternative,  and  it  would  not  be  easy  to  devise  experiments 
which  would  elucidate  even  that  much.     They  would  not  indicate 
the  nature  of  memory.     The  problem  is  one  for  the  thinker,  not 
the  experimental  observer.     Biometricians,  as  we  shall  see,  have 
worked  on   the  assumption  that  various  characters  which  seem 
clearly  part  of  the  contents  of  memory  are  '  innate '  or  instinctive. 
Indeed,  it  is  probable  that,  more  than  any  other  section  of  biologists, 
they  have  failed  to  realize  the  importance  of  the  acquired  factor  in 
the  human  mind.1 

675.  Speaking  generally,  very  recent  writers  who  deal   with 
mental  evolution  suppose  that  first  reflex  action,  then  instinct,  and 
lastly  intelligence  and  reason  were  evolved  ;  other  faculties  such  as 
imagination,  discrimination,  and  the  power  of  drawing  inferences, 
being  variously  placed  in  the  general  scale.     There  seems  good 
reason  to  believe,  however,  that  the  true  order  of  the  evolution  was 
first  reflex  action,  next  instinct,  and  lastly  memory.     Imagination, 
intelligence,  reason,  and  the   rest  are   merely   operations   which 
animals  perform  because  their  memories  have  undergone  sufficient 
evolution.     Without  memory  there  could  be  no  such  faculties  ;  for 
they  are  concerned  solely  with  the  contents  of  memory,  associating, 
comparing,  discriminating,  adding  to  them.     In  a  real  sense  they 
are  themselves  part  of  the  contents  of  memory ;  for  infants  learn 
to  think  just  as  truly  as  they  learn  to  walk  or  learn  the  facts  about 
which  they  think.     The  range  and  quality  of  the  thinking  are 
entirely  conditioned,  on  the  one  hand,  by  knowledge,  and,  on  the 
other,  by  the  power  of  learning  to  think  ;  that  is,  from  first  to  last 
by  memory. 

1  See  §§  706  et  seq. 


CHAPTER  XXII 
NATURE  AND  NURTURE 

Acquired  emotional  impulses  are  copies  of  instincts,  and  automatic  actions  of 
reflexes — Distinction  between  reflexes  and  automatic  actions — The  way  in  which 
our  dexterities  arise — The  fovea  centralis  of  attention  and  will — Automatic 
actions  differ  from  reflex  actions  in  that  they  are  controlled  by  the  attention  and 
the  will — Dreams — The  distinction  between  recollection  and  bearing  in  mind — 
The  difference  between  physical  and  mental  acquirements — Nature  and  nurture — 
Capacity  and  mental  acquirements — Ability  and  efficiency — The  factors  of 
efficiency — Instincts  and  acquirements — Imbeciles — Racial  mental  characteristics 
— The  influence  of  religion — Opinions  founded  on  biometry. 


SPEAKING  generally,  the  impulses  to  action  (emotions) 
which  we  gradually  acquire  and  store  in  our  memories, 
for  example,  patriotism  and  religious  enthusiasm,  are 
all  close  copies  of  instincts.  They  resemble  instincts  in  all 
except  their  mode  of  origins.  Like  them  they  prompt,  with 
various  degrees  of  urgency,  to  voluntary  actions.  The  resemblance 
is  made  all  the  closer  by  the  fact  that,  just  as  a  great  deal  of  our 
acquired  physical  growth  is  a  prolongation,  a  mere  continuation,  of 
growth  that  was  previously  made  under  the  stimulus  of  nutriment, 
so  some  of  our  acquired  impulses  to  action  (e.g.  love  for  some  one 
woman,  a  curiosity  concerning  some  particular  science),  are  pro- 
longations or  reinforcements  of  instincts.  In  other  words,  many 
of  our  permanent  impulses  to  action  are  partly  instinctive  and 
partly  acquired  ;  and  the  acquired  part  of  the  emotion  so  closely 
resembles  the  inborn  portion  that  we  cannot  distinguish  where  the 
one  begins  and  the  other  ends.  The  resemblance  is  made  yet 
closer  by  the  fact  that  the  performance  of  only  a  few  of  the  actions 
to  which  human  instincts  (e.g.  the  sexual  and  the  parental)  prompt 
are  instinctive  in  the  sense  that  they  can  be  performed  without 
previous  learning.  Thus  the  human  mother  not  only  acquires  the 
special  learning  which  enables  her  to  tend  her  child,  but  during 
her  own  infancy  acquired  the  necessary  power  of  co-ordinating  the 
muscles  of  her  limbs.  The  question,  then,  arises  whether  imitation 
reflexes  (automatic  actions)  are  as  close  copies  of  real  reflexes  as 
acquired  emotions  are  of  instincts.  We  learn  to  do  habitual 

410 


AUTOMATIC  ACTIONS 

actions,  for  example,  walking,  speaking,  writing,  reading,  sewingj 
cycling,  swimming,  and  the  like,  with  toil  and  difficulty.  At  first 
the  performance  is  awkward,  and  the  action  on  which  we  are 
engaged  requires  our  '  undivided '  attention.  Gradually,  however, 
performance  grows  more  facile  till  at  length  we  are  able  during  it 
to  do  some  other  less  habitual  action  at  the  same  time.  The 
latter,  then,  in  turn  requires  our  'concentrated'  attention,  until, 
perhaps,  it  also  becomes  habitual.  When  an  action  has  become 
so  easy  of  performance,  so  habitual,  that  we  are  able  to  do  it 
1  unconsciously/  it  is  said  to  be  automatic.  It  is  then  so  close  a 
copy  of  reflex  action  that  psychologists  usually  include  it  in  that 
category. 

677.  A  true  reflex,  as  we  have  seen,  is  not  initiated  by  the  will* 
and  is,  besides,  an  action  which  the  individual  is  born  with  the 
power  of  performing.  Therefore,  it  resembles  an  instinctive  action 
in  that  the  power  of  perfoming  it  is  innate,  but  differs  from  the 
latter  in  that  it  is  involuntary;  whereas  it  differs  from  an  auto- 
matic action  in  that  the  power  of  performing  it  is  innate,  not 
acquired.  The  problem  before  us  is  whether  automatic  actions 
resemble  true  reflexes  in  being  quite  involuntary.  The  question  is 
important,  for,  as  I  say,  psychologists  usually  include  automatic 
actions  amongst  the  reflexes,  just  as  they  often  include  acquired 
emotions  amongst  the  instincts ;  with  the  result  that  the  full  im- 
portance of  the  distinction  between  the  inborn  and  the  acquired, 
and,  therefore,  the  part  played  by  acquirement  (i.e.  the  contents  of 
the  memory)  in  the  building  up  of  the  normal  human  mind  is  lost 
to  sight.  We  have  here  no  mere  question  of  nomenclature,  nor 
even  merely  a  problem  of  pure  science.  Immense  practical  issues 
hang  on  the  conclusions  we  reach.  For  example,  if  we  were  able 
to  attain  a  thorough  knowledge  and  agreement  as  to  how  the 
human  mind  developed — what  it  is  possible  and  what  impossible 
to  create  or  eliminate  by  means  of  careful  mental  training — we 
should  also,  in  all  probability,  be  in  equal  agreement  as  to  the  best 
methods  of  educating  our  children.  Even  if  a  thorough  knowledge 
and  agreement  be  unattainable  by  us,  we  shall,  nevertheless,  be 
nearer  both  if  we  found  our  conclusions  on  careful  investigation, 
instead  of  careless  assumption. 

678.  A  few  facts  may  be  first  noted,  (i)  Every  automatic 
action  (e.g.  knitting,  cycling)  was  clearly  voluntary  when  first  we 
began  to  learn  it.  (2)  As  a  rule,  any  action  which  has  become 
automatic  is  still  clearly  voluntary  when  we  begin  to  perform  it; 
thus,  we  usually  begin  to  walk  through  an  impulse  which  is  plainly 


412  NATURE  AND  NURTURE 

due  to  an  exercise  of  will,  though  afterwards,  when  we  are  thinking 
of  other  things,  the  performance  becomes  automatic.  (3)  Every 
clearly  voluntary  action  is  now  in  part  automatic,  for  we  have 
learned  a  general  automatic  power  of  co-ordinating  our  muscles 
for  every  kind  of  action.  (4)  Every  automatic  action  becomes 
voluntary  directly  our  attention  is  concentrated  on  it;  thus,  the 
automatic  action  of  a  woman  who,  when  she  is  knitting,  thinks  of 
other  things,  becomes  clearly  voluntary  when  she  concentrates  her 
attention  on  her  work. 

679.  At  the  back  of  the  eye  is  a  small  spot,  the  fovea  centralis^ 
which  is  the  region  of  the  most  acute  vision.     When  we  wish  to 
see  an  object  distinctly,  we  turn  our  eyes  so  that  the  retinal  image 
of  it  falls  on  the  fovea  centralis.     That  constitutes  the  action  of 
fixing  our  eyes  on  the  object.     The  images  of  the  other  objects 
within  the  area  of  sight  are  cast  on  the  peripheral  regions  of  the 
retina  surrounding  the  fovea>   and  are  seen  much  less  vividly — 
those  nearest  the  fovea  being  most,  and  those  farthest  least  dis- 
tinctly seen.     Normally,  when  we  are  attending  to  the  things  we 
see,  the  major  part  of  our  attention  is  concentrated  on  the  object 
on  which  the  sight  is  fixed.     But  we  are  not  entirely  oblivious  of 
its  setting,  for  any  unexpected  occurrence  within  the  area  of  sight 
immediately  attracts  our  concentrated  sight  and  attention,  which 
could  not  happen  were  we  quite  unconscious  of  it.     This  diffusion  of 
some  of  our  sight  and  attention  while  most  of  them  are  concentrated 
on  particular  objects  is  extremely  useful ;  for  thereby  the  concen- 
trated faculties  are  continually  guided  to  fresh  objects  of  interest 
or  importance.     Thus,  having  sufficiently  admired  one  flower  on  a 
bush,  our  sight  and  attention  does  not  wander  vaguely  round  in 
search  of  other  objects  of  admiration,  but  swiftly  passes  to  flowers 
which  previously  were  marked  on  the  peripheral  portion   of  the 
retina.     The  recollection  of  the  first  flower  is  then  stored  in  the 
memory,  and  to  it,  as  our  concentrated  sight  and  attention  wander 
about,   we   are   able   to   add    memories   of  other   flowers.      Con- 
sequently, we  do  not  live  solely  in  the  immediate  present.     We 
are  able  to  compare  the  various  flowers  on  the  bush  with  one 
another  and  with  flowers  seen  perhaps  long  ago.     Thus  our  minds 
are  built  up. 

680.  It  seems,  then,  as  regards  the  objects  of  sight,  we  are  able 
to  attend  to  more  than  one  thing  at  a  time.     At  any  moment,  our 
attention  is  more  or  less  concentrated  on  one  thing,  but  some  of  it  is 
diffused,  with  varying  but  much  lesser  degrees  of  concentration,  on 
other  things.     The  object  on  which  our  sight  is  for  the  time  being 


THE  ATTENTION  413 

fixed  is,  as  a  rule,  of  all  the  objects  within  sight,  the  most  interesting 
to  us  during  that  time.  For  that  reason  we  'look  at'  it.  For  that 
reason  it  '  claims  our  attention.'  Sometimes,  indeed,  but  then  only 
by  a  conscious  effort,  we  do  not  concentrate  our  attention  on  the 
object  of  sight  on  which  our  eyes  are  fixed,  but  on  some  other 
object  in  the  peripheral  area  of  vision.  Thus,  in  a  drawing  room, 
though  we  may  be  gazing  full  at  the  face  of  a  friend,  we  may 
really  be  watching  through  the  '  corner  of  our  eye '  the  pretty  girl 
beside  us,  who  is  talking  to  some  one  else.  More  commonly, 
however,  when,  as  is  often  the  case,  we  are  '  not  attending '  to  the 
object  that  falls  on  the  fovea  centralis  of  the  retina,  our  attention 
is  concentrated,  not  on  any  object  of  sight,  but  on  something  else. 
Thus,  while  we  are  almost  entirely  oblivious  of  our  friend  or  the 
pretty  girl,  we  may  be  concentrating  our  attention  on  some 
interesting  gossip  that  is  being  whispered  behind  us.  Our  con- 
centrated attention,  the  fovea  centralis  of  our  attention,  wanders, 
like  the  fovea  centralis  of  the  eye,  from  one  sensation  (auditory, 
tactile,  etc.)  to  another ;  or  it  may  ignore  sensations  altogether, 
and,  as  when  we  are  in  a  brown  study,  be  concerned  only  with  our 
thoughts.  Our  concentrated  attention  is  what  is  colloquially  termed 
1  active,'  while  the  diffused  attention  is  termed  '  mechanical.'  Thus, 
when  we  are  thinking  of  the  pretty  girl  or  the  gossip,  we  are 
actively  attending  to  one  or  the  other  and  mechanically  to  our 
friend.  But  the  latter  attention,  however  mechanical,  however 
diffused,  is  still  attention.  We  are  not  quite  oblivious  of  the 
friend.  We  still  converse  mechanically. 

68 1.  The  degree  of  concentration  of  attention  varies  greatly. 
It  may  be  so  concentrated  that  we  are  almost  unconscious  of  the 
rest  of  our  surroundings.  It  may  be  so  diffused  that  it  is  hard  to 
say  which  object  is  claiming  the  most  of  our  attention.  But  there 
always  is  some  concentration  and  some  diffusion.  Now,  we 
invariably  remember  best  those  things  on  which  we  have  concen- 
trated our  attention  most.  Thus,  as  a  rule,  we  can  recall  only  the 
seen  things  on  which  we  have  fixed  our  sight,  and  even  then  only 
when  we  have  paid  attention  to  them  at  the  time.  All  the  rest 
we  have  seen,  or  otherwise  felt,  is  vague  in  recollection,  if  it  be 
recollected  at  all,  in  proportion  to  the  degree  of  the  diffusion  of 
the  attention.  Thus,  I  have  been  invited  to  see  an  interesting 
town,  by  a  friend  who  was  even  more  interesting,  and  have  walked 
miles  with  him,  and  have  come  away  with  hardly  a  recollection  of 
the  place,  but  full  of  vivid  remembrances  of  what  my  friend  said. 
If  he  had  been  less  interesting  I  should  have  remembered  more  of 


4H  NATURE  AND  NURTURE 

the  town.  Doubtless,  in  that  case,  my  concentrated  attention 
would  have  fluctuated  back  and  forth  from  him  to  it.  Since, 
however,  only  my  diffused  attention  was  given  to  the  town,  I 
remember  little  of  it.  Only  enough  attention  was  given  to  enable 
me  to  walk  about  and  avoid  obstacles. 

682.  The  will  is  associated  with  the  attention.     We  never  will 
to  do  anything  unless  our  attention  is  attracted  to  it.   We  are  able  to 
do  several  actions  at  once.    Thus  a  few  minutes  ago  I  was  standing, 
smoking,  pouring  water  into  a  cup,  stirring  its  contents,  and  trying 
to  think  of  a  good  example  of  several  actions  done  simultaneously. 
My  attention  was  concentrated  on   the  last-mentioned    act,  the 
others  being  more  or  less  automatic.     Were  they,  or  were  they 
not  under  the  constant  control  of  my  will  ?     Suddenly  it  occurred 
to  me  that  my  action  at  the  time  afforded  the  example  I  required. 
Thereupon,  as  I  noticed  immediately,  I  ceased  to  smoke,  to  incline 
the  kettle,  and  to  stir  the  cup.     I  do  not  know  how  it  is  possible 
to  explain  these  cessations,  except  by  supposing  that   the  new 
thought  occupied  so  much  of  my  attention,  and  therefore  of  my 
will,  that  the  latter  ceased  to  direct  the  smoking,  inclining,  and 
stirring,  though  the  still  more  automatic  actions  of  standing  and 
holding  the  kettle  continued.    Had  my  attention  been  very  strongly 
concentrated  it  is  possible  that  even  they  might  have  ceased.     I 
remember,  as  a  student  in  Edinburgh,  watching  with  mischievous 
expectation  a  party  of  tourists  in  whose  near  neighbourhood  a 
signal  cannon,  unsuspected  by  them,  was  about  to  be  discharged. 
At  the  sound  of  the  explosion  almost  all  action  ceased  for  an 
instant  in  the  crowd.      It  stood  as  if  paralysed.      Many  of  its 
members  let  fall  sticks  and  parasols,  and  many  seemed  *  ready  to 
drop ' — to  cease  the  automatic  action  of  standing.     Similarly,  any- 
thing that  interests  us  very  greatly  tends  to  cause  cessation  of 
automatic  action  unless  some  of  our  attention  is  directed  to  it  by 
conscious  effort.     On  the  other  hand,  during  ordinary  preoccupa- 
tion, we  are  able  to  hold  within  the  peripheral  parts  of  our  atten- 
tion things  we  desire  to  bear  in  mind.     This  happens  even  during 
sleep,  for  often  we  are  able  to  wake,  if  we  desire  it,  at  an  earlier 
hour  than  usual.     It  seems,  then,  that  even  the  most  automatic  of 
our  actions  is  maintained  only  because  some  part  of  our  attention  is 
directed  to  it,  and  some  part  of  our  will  engaged  in  its  performance. 

683.  I  think,  therefore,  there  can  be  no  doubt  that  automatic 
actions  differ  from  reflexes,  not  only  in  that  the  ability  to  perform 
them    is   acquired,    but   also   because    they   are   always  initiated, 
controlled,  and   guided  throughout  by  the   will.     Therefore  they 


FAMILIAR  AND  SURPRISING  THINGS  415 

are  not  such  close  copies  of  reflex  actions  as  certain  other  actions 
are  of  instinctive  doings.  While  we  are  learning  to  perform  them 
they  engage  our  attention  and  will  strongly.  But  as  they  become 
habitual  and  are  performed  with  increasing  ease,  we  are  able  to 
distract  more  and  more  of  the  attention  and  the  will  to  less 
habitual  actions;  but  never  the  whole  attention  and  will.  The 
will  does  not  fall  into  abeyance  as  we  become  dexterous,  it  merely 
works  very  smoothly  and  easily  so  that  little  mental  effort  is 
required.  As  already  noted,  it  is  one  of  the  main  businesses  of  our 
lives  to  acquire  the  power  of  performing  frequently  recurring 
actions  automatically,  and  so  set  free  the  concentrated  part  of  the 
attention  and  the  will — the  fovea  centralis  of  our  attention  and 
will — for  other  objects. 

684.  It  is  said  sometimes  that  lower  animals  differ  so  much 
from  us  in  brain  and  mind  that  we  can  form  no  conception  of  their 
mental  states.     Doubtless  this  is  true  in  a  great  measure.     The 
senses   and,  therefore,  the  outlook   on  the  world  as  well  as  the 
instincts  of  many  animals  differ  greatly  from  ours.     Moreover,  no 
other  animal  possesses  such  an  enormous  memory  as  man  ;  none, 
therefore,  learns  so  much  about  the  world  or  is  so   preoccupied 
with  the  past  and  the  future.     On  the  other  hand,  since  most  of 
our  instincts  and  those  of  lower  animals  are  derived  from  progeni- 
tors that  were  common  ancestors,  our  innate  emotional  impulses 
cannot  be  very  different ;  and,  though  our  powers  of  thought  are 
transcendently  great,  yet  all  that  is  conferred  by  our  unconscious 
memories,  our  '  physical '  dexterities  and  mental  attitudes,  includ- 
ing many  of  our  prepossessions  and  prejudices,  tend  to  become 
close  copies  of  instincts  and  instinctive  activities.     It  is  possible  to 
imagine  a  state  of  mind  in  which  experiences  are  not  recognised  as 
old    acquaintances — a   state   of  mind    in  which   nothing   appears 
familiar  or  unfamiliar ;  in  which  everything  is  taken  as  a  matter 
of  course  and  nothing  causes  surprise  ;  in  which  there  is  no  idea 
of  the  past  or   of  the    future   but   only  a   consciousness   of  the 
immediate  present ;  in  which,  while  most  sights,   sounds,  tastes, 
tactile  sensations,  and  the  like  leave  us  unmoved,  some  of  these  con- 
centrate our  attention  and  will  and  incite  more  or  less  vehemently  to 
definite  actions  the  aims  and  ends  of  which  are  unthought  of.     Such 
a   state  of  mind  should  be  very  like  that  of  purely  instinctive 
animals.     Things  are  familiar  or  unfamiliar  only  because  memory 
differentiates  between  the  two,  and  surprising  things  are  surprising 
only   because    they   run   counter    to   our   previous   experiences.1 

1  See  §  561. 


416  NATURE  AND  NURTURE 

Doubtless,  an  African  elephant  or  a  dragon  from  the  pit  would 
excite  no  greater  interest  or  surprise  than  a  rabbit  in  a  new  born 
baby  or  in  a  beetle  of  any  age. 

685.  Probably  our  dream  world  resembles  in  great  measure  the 
real  world  of  a  purely  instinctive  animal.     In  proportion  to  the 
depth  of  our  slumber,  our  memory,  or  some  part  of  it,  seems  in 
abeyance.     We  may  "  know  sleeping  thoughts  at  the  moment  they 
arise,  and  not  retain  them  the  next  moment."  *•     As  a  medical  man 
I  am  frequently  rung  up  at  night,  and,  having  formed  the  habit  of 
taking  note,  I  observe  that,  invariably,  I  awaken  out  of  a  dream, 
which  I  remember  if  I  mentally  record  it  without  delay,  but  which 
otherwise  I   forget  almost  immediately,  especially  if  I  am  roused 
out  of  very  deep  slumber.     In  lighter  slumber,  when   I  hover  on 
the  borders  of  waking,  memory  also  is  more  awake.     It  is  then  I 
have  my  *  vivid  '  dreams,  those  I  remember  best.     I  think,  there- 
fore, that  my  mind  as  a  whole  never  sleeps.      In  deepest  sleep  I 
dream  and  weave  the  sensations  that  come  to  me  from  my  body 
into  the  fabric  of  my  dreams.     Of  all  my  mind  my  memory  alone 
rests,  more  or  less  profoundly,  when  I  sleep  ;  and,  when  I  awake,  it 
is  my  memory  that  awakes. 

686.  The  main  differences  between  our  sleeping  and  waking 
mental  experiences  arise  from  the  fact  that  we  are  unable  to  store, 
to  profit  from,  the  former.     They  are  not  retained  in  the  memory 
to  anything  like  the  same  extent  as  the  latter.     Moreover,  when 
dreaming  we  refer  to  experiences  recognized  as  past  much  less 
than  when  awake.     We  live   mainly   in  the  immediate   present, 
accepting    experiences,    as    they   arise,   without    to    any    extent 
consciously  associating  them  with  what  has  gone   before.     It  is 
thirty  years  since  I  studied  for  the  Royal   Engineers  and    more 
than  twenty  since  I  sought  to  become  a  medical  student.     Never- 
theless, occasionally  I  am  still  rendered  miserable  when  asleep  by 
the  thought  that  I  may  be   *  ploughed '  in  Latin.     All  that  has 
happened  between  youth  and  middle  age  is  quite  forgotten.     It  is 
true  that  the  objects  we  see  in  our  dreams  have  usually  been  stored 
in  our  memories  whence  they  are  evoked ;  but  they  do  not  come 
to  us  surrounded,  as  it  were,  by  a  halo  of  recollections.     They  are 
not  usually  greeted  as  remembered  things.     We  feel  that  they  are 
good  or  bad,  delightful  or  horrifying,  just  because  they  seem  by 
nature  to  be  so,  not  because  of  the  recollections  with  which  they 
are  invested — as  if  the  physical  characters  in  the  brain  with  which 
they    are    correlated    had    developed    through    the   stimulus   of 

5  Isaac  Walton. 


THE  DREAMING  STATE  417 

nutrition,  not  through  that  of  use  and  experience — as  if  they  had 
developed  as  Adam's  navel  is  said  by  the  theologians  to  have 
developed.  Just  so  might  an  insect  see  his  hitherto  unimagined 
mate  or  enemy  with  delight  or  fear. 

687.  I  dreamed  lately  that  I  sat  in  a  railway  carriage  suffering 
from  headache,  which  a  commercial  traveller  who  was  next  to  me 
tried  to  cure.  I  felt  extremely  grateful.  At  the  same  time,  as  quite 
an  independent  person  who  knew  nevertheless  he  was  the  same 
person  as  the  sufferer,  I  sat  opposite,  and  marked  the  proceedings 
of  the  traveller  with  some  professional  contempt  and  disapproval. 
The  personalities  of  sufferer  and  observer  alternated  rapidly,  but  I 
accepted  without  question  the  fact  that  I  was  both.  Because  in 
my  waking  hours  I  appeal  to  past  experience  and  therefore  am 
able  to  reason  from  it,  I  know  now  that  the  situation  was  an 
impossible  one ;  but  I  did  not  appeal  to  it  then.  In  another 
dream  I  looked  at  the  top  of  my  own  head  as  I  lay  asleep  and 
noted  with  regret  but  no  surprise  that  I  was  extremely  bald.  In 
my  dreams  I  have  flirted  with  Queen  Elizabeth  and  in  the  same 
night  have  been  in  heaven  and  hell  and  have  not  been  astonished 
that  the  one  bestowed  no  more  delights  than  the  other.  Dreams, 
being  thoughts,  are  as  '  swift  as  thought ' :  between  two  intervals 
of  waking — five  minutes  by  the  clock — I  have  dreamed  volumes. 
Yet  of  all  the  immense  mass  of  our  dream  experiences  how  little 
we  remember !  Though,  as  I  say,  I  appear  always  to  dream  when 
asleep  I  recollect  nothing  that  occurs  during  deep  sleep  unless  I 
am  suddenly  awakened  and  at  once  make  the  record.  Even  of 
the  visions  of  light  sleep  I  commonly  remember  little.  It  is 
significant,  that  though  recollection  slumbers,  yet  all  the  instinc- 
tive emotions  may  be  felt  during  sleep.  On  all  counts,  therefore, 
it  seems  evident  that  the  faculty  that  slumbers  more  or  less  deeply 
during  sleep  is  memory,  and  more  especially  the  part  of  memory 
which  is  concerned  in  recording  (not  recalling)  experiences.  In 
other  words  though  we  have  plenty  of  experiences  during  sleep  our 
minds  do  not  then  grow  under  their  stimuli.  We  become  like 
instinctive  animals ;  we  neither  record  facts  nor  grow  dexterous 
in  using  them.  Since  reason  deals  with  the  contents  of  memory 
and  is  itself  one  of  the  contents,  reason  also  sleeps  with  a  sound- 
ness which  is  in  proportion  to  the  soundness  with  which  the 
memory  slumbers.1 

1  See  Sir  Arthur  Mitchell's  most  interesting  work  Dreaming,  Laughing,  and 
Blushing,  pp.  5-9.     It  is  sometimes  said  that  intoxication  is  marked  by  a  pro- 
gressive loss  of  faculties  beginning  with  the  highest,  the  last  evolved,  and  ending 
27 


4i8  NATURE  AND  NURTURE 

688.  Do  purely  instinctive  animals  sleep  ?     If  they  do,  what  is 
the  faculty  that  slumbers  ?     When  they  rest,  as  a  fly  in  darkness, 
and  hardly  any  stimulus  awakens  their  senses,  are  they  unconscious 
in  a  truer   sense   than  we   are   during   sleep?     Or  do    they  also 
see  visions  ?     Our  visions  are  supplied  by  a  more  or  less  paralysed 
memory  ;  what  supplies  their  visions,  if  they  have  any  ?     Most  of 
the  experiences  stored  in  our  memories  are  acquired  through  the 
sense  of  sight.     Is  the  fact  that  all  animals  with  well  developed 
memories  close  their  eyes  during  sleep  connected  with  the  fact 
that  their  memories  need  rest  ?     It  is  true  that  the  eyes  of  such 
animals  are  especially  vulnerable,  but  that  peculiarity  may  be  the 
effect  not  the  cause  of  the  fact  that  eyes  are  covered  by  eyelids. 
Apparently  the  eyes  of  insects  see  well  enough ;  and  yet  they  are 
not  protected. 

689.  Many  insects,  for  example  solitary  wasps,  are  not  pro- 
tected during  the  beginnings  of  conscious  life  by  their  parents. 
Therefore,  of  necessity,  they  are  fully  or  almost  fully  equipped  for 
the  battle  of  life  by  instinct.     Nevertheless  they  are  able  to  return 
burdened  with  loads  of  food  to  the  cells  in  which  they  have  de- 
posited their  eggs.     By  what  means  do  they  find  the  road — by 
instinct  or  memory?     The  word  memory  is  used  in  two  senses, 
one  of  which  implies  recollection,  and  the  other  bearing  in  mind. 
We  recollect  when  we  recall  an  experience  which  was  formerly  in 
consciousness  but  has  passed  out  of  it ;  we  bear  in  mind  when  we 
keep  an  experience  in  consciousness.     Thus  I  recollect  a  blow  if, 
after  the  memory  of  it  has  passed  out  of  consciousness,  a  sight  of 
my  opponent  recalls  the  experience.     I  bear  in  mind  if  I  continue 
to  dwell  on  the  experience  after  having  been  struck.     Probably 
the  kind  of  memory  which  is  absent  in  purely  instinctive  animals 
is  the  power  of  storing  experiences  so  that  they  may  be  recalled. 
Therefore  it  is  possible  that  the  wasp  may  instinctively  bear  in 
mind,  during  all  the  vicissitudes  of  her  hunt  for  food,  the  situation 
of  her  nest ;   in  which  case,  she  is,  like  higher  animals,  able  to 
attend  to  more  than  one  thing  at  a  time.     On  the  other  hand,  if 
she  recalls  the  situation  of  her  nest,  of  which  she  was  previously 
unmindful,  she  possesses  a  true  memory ;  but  in  that  case,  since 
she  is  very  incapable  of  learning  other  things x  she  has  a  memory 

with  the  lower,  the  more  anciently  evolved.  The  interpretation  of  this  appears 
to  be  that  intoxication,  like  sleep,  is  a  kind  of  paralysis  by  which  the  memory  in 
particular  is  affected.  The  highest  faculties  and  the  most  skilful  actions  are  those 
which  depend  on  the  greatest  amount  of  stored  experience.  The  '  brute  '  muscular 
strength  and  the  innate  mental  and  nervous  characters  (instincts  and  reflexes) 
are  relatively  little  affected.  l  See  Lubbock,  Ants,  Bees,  and  Wasps, 


HUMAN  MENTAL  ACQUIREMENTS  419 

which  is  capable  of  storing  only  a  particular  and  a  very  limited 
set  of  facts.     The  latter  hypothesis  seems,  at  least,  improbable. 

690.  From  birth  to  adult  age  our  physical  development  is  due 
mainly  to  the  stimulus  of  use.     After  the  attainment  of  manhood 
almost  all  growth  which  is  not  pathological  or  a  mere  storing  of 
spare  nutriment  as  fat,  is  due  to  that  cause.    The  growth  thus  made 
during  youth  is  enormous,  but  it  occurs  only  on  certain  predestined 
lines  and  within  well-defined  limits.     By  limiting  the  amount  of  use 
to  which  this  or  that  structure  is  put  we  may  limit  its  growth ;  by 
putting  the  structure  to  a  more  than  normal  amount  of  use  we 
may  increase  its  size  somewhat  beyond  the  '  normal.'     But  there 
our  power  ends.     The  hand  is  put  to  a  greater  variety  of  uses  than 
any  other  organ  in  the  body.    Yet,  even  if  we  begin  with  the  infant, 
we  can  only  make  it  large  and  coarse,  or  small  and  fine.     It  still 
remains  a  hand  which  closely  resembles  in  size  and  shape  altogether 
normal  hands.     It  is  very  different  in  the  case  of  mind.     Consider 
the  millions  of  '  physical '  dexterities  we  are  capable  of  learning. 
These  are  all  really  mental.     For  example,  our  hands  do  this  or 
that  thing  dexterously  because  our  minds  have  learned  to  direct 
them  readily  and  rightly.     The  '  normal '  dexterity  of  the  penman 
differs  widely  from  that  of  the  woodcutter,  the  sailor's  from  that  of 
the  surgeon.     Yet  any  of  them  may  be  acquired  by  the  average 
young  individual.     But  physical  dexterities  are  as  nothing  com- 
pared to  the  rest  of  our  mental  acquirements  ;  they  are  as  nothing 
compared  even  to  the  mental  acquirements  that  are  most  closely 
related  to  them.     Thus,  the  architect's  manual  skill  with  ruler  and 
pencil  is  but  a  small  part  of  his  total  mental   acquirements  as 
architect,  and  that  again  is  but  a  small  part  of  his  total  mental 
equipment  as  a  man  of  the  world,  his  other  physical  dexterities,  his 
acquired  mental  attitudes,  his  knowledge  of  men  and  things.     The 
average  man  is  capable  of  becoming  an  average  architect;    or, 
instead,  he  may  acquire  skill  in  one  or  more  of  a  thousand  other 
occupations. 

691.  Physically  most  of  us  could  fill  the  places  of  most  other 
men ;  that  is  our  physical  structures   are   capable  of  doing  the 
work  that  their  physical  structures  do.     Mentally  not  one  of  us 
is  capable  of  filling  the  place  of  any  other.     I,  for  example,  though 
as  large  and  strong  in  body,  could  not  mentally  fill  the  place  of  a 
workman  with  whom  I  am  acquainted.     I  have  not  the  same  skill 
and  mental  attitudes  which  have  fitted  him  into  a  certain  niche,  the 
same  prejudices,  the  same  ethics,  the  same  knowledge  of  his  world 
based  on  past  experience.     My  religious  and  political  convictions 


420  NATURE  AND  NURTURE 

are  different.  I  do  not  love  the  same  old  people,  the  same  wife,  the 
same  children,  the  same  fireside,  the  same  friends.  Yet  I  might 
well  have  fitted  his  niche  had  I  been  reared  to  it. 

692.  It  is  evident,  therefore,  that  while  human  bodies  can  grow 
in  only  one  way,  human  minds  may  grow  in  any  one  of  a  thousand 
ways.  As  already  noted,  if  the  child  of  refined  and  educated 
English  parents  were  reared  from  birth  by  African  cannibals,  then 
in  body,  when  grown,  he  would  resemble  his  progenitors  more 
than  his  trainers.  Does  anyone  believe  that  the  same  would  be 
true  of  his  mind  ?  All  Anglo-Indians  know  the  disastrous  effects 
of  too  much  association  with  natives  on  the  plastic  minds  of  white 
children.  They  become  unfitted  for  the  environment  of  the 
average  Englishman.  Even  when  an  adult  young  Englishman 
migrates  to  the  United  States  or  the  colonies  and  returns  after 
twenty  years,  we  perceive  marked  mental  differences  between  him 
and  his  stay-at-home  contemporaries.  Indeed,  he  seems  to  us 
to  have  become  quite  similar  to  the  people  with  whom  he  has 
dwelt,  though,  doubtless,  Americans  or  colonists,  whose  observa- 
tion is  sharpened  by  familiarity  can  detect  differences.  The 
English  child  we  imagined  as  reared  by  African  savages  would 
certainly  display  no  hint  of  the  language  and  general  knowledge 
of  his  parents,  no  tincture  of  their  moral,  social,  religious,  and 
political  ideals  and  aspirations.  He  would  ruthlessly  murder  and 
enjoyingly  eat  the  stranger.  He  would  harry  the  stranger's 
property  and  annex  the  stranger's  wives  by  the  wool  of  their  heads 
whenever  practical.  He  would  treat  his  own  wives  as  beasts  of 
burden,  and  perhaps  thrash  them  0.3  a  matter  of  routine.  His 
aesthetic  ideals  would  be  satisfied  by  a  little  paint,  some  beads, 
and  plenty  of  grease ;  his  moral  ideas  by  a  homicidal  devotion  to 
the  tribal  chief.  His  god  would  be  the  tribal  fetish,  to  whom  he 
would  offer  human  sacrifices.  He  would  go  naked  and  unashamed. 
The  common-sense  of  mankind  has  universally  recognised  this 
radical  difference  between  man's  mind  and  body.  We  allow  our 
children  to  train  their  own  bodies,  being  satisfied  that  they  will 
develop  physically  well  enough  under  the  influence  of  sufficient 
food  and  the  exercise  to  which  the  instinct  of  play  impels  them  ; 
but  to  the  training  of  their  minds  we  devote  the  most  anxious 
care.  We  mould  them,  and  we  know  we  mould  them.  No  one 
fears  that  his  child  will  be  made  short  or  dark  by  association 
with  short  or  dark  companions ;  but  everyone  dreads  that 
his  child  may  become  silly  or  bad  if  his  associates  are  silly  or 
bad.  Clearly,  then,  the  mind  of  the  individual  is  'shaped'  by 


CAPACITY  AND  ACQUIREMENT  421 

his  immediate  surroundings  in  a  much  greater  degree  than  his 
body. 

693.  Sometimes  it  is  asked  if  nature  or  nurture  plays  the  more 
important  part  in  the  mental  development  of  the  human  being. 
As  a  fact  this  question  is  nonsensical.     It  is  as  if  we  asked  whether 
the  locomotive  or  the  steam  played  the  greater  part  in  transporting 
the  train.     The  truth   is  that   nature   has   rendered    man   trans- 
cendently  responsive  to  the  nurture  of  use  and  experience.     The 
question  should  be  "To  what  extent  has  nature  rendered  man 
responsive  to  the  stimulus  of  nutriment  and  to  what  extent  to  that 
of  use  and  experience?"     Nature  has  rendered  all  living  beings 
equally  responsive  to  nurture.     The  caterpillar  is  responsive   to 
the  nurture  of  nutriment.     Man  differs  from  the  caterpillar  in  that 
nature  has  rendered  him  responsive  in  addition  to  the  nurture  of 
use  and  experience.     He  differs  from  other  animals  in  that  he  is 
immensely  the  most  responsive  of  all  to  this  kind  of  nurture.     It 
is  the  one  peculiarity  which  strongly  differentiates  him.     Mental 
experience  is,  after  all,  only  a  form  of  use.     We  use  our  minds 
when  we  store  experiences;   or  rather,  if  mind  is  a  function  of 
brain,  we  use  our  brains.     When,  for  example,  we  acquire  a  new 
manual  dexterity,  our  brains  acquire  a  new  function ;  through  use 
they   learn   to  do  a  new  thing.     Doubtless  the   acquirement   is 
accompanied  by  actual  growth  of  brain,  which  however,  especially 
in  adult  life  when  gains  are  being  balanced  by  losses,  need  not 
imply  an  increase  in  bulk,  but  only  a  relative  increase  in  certain 
of  the   brain   constituents   such   as   nerve    cells    or   connections 
between  nerve  cells.     In  youth,  when  man  is  making  the  great 
mass  of  his  mental  acquirements  including  the  more  important  of 
his  '  physical '  and  mental  dexterities  (e.g.  walking  and  reasoning), 
there  is  rapid  growth  in  the  bulk  of  the  brain,  which  is  most  rapid 
just  when  the  acquirements  are  being  most  rapidly  made.     In  old 
age,  though  the  individual  may  still  be  making  mental  acquire- 
ments, he  is  usually  losing  more  than  he  acquires.     Then,  while 
the  total  mass  of  his  brain  does  not  decrease,  the  nervous  elements 
tend  to  be  replaced  by  fibrous  tissue. 

694.  If  we  wish  to  avoid   hopeless  confusion  it  is   necessary 
to   distinguish   sharply   between    two    entirely   different    things ; 
between,  on  the  one  hand,  capacity  to  make  mental  acquirements, 
and,  on  the  other,  the  mental  acquirements  themselves,  between 
the  memory  and  the  things  that  are  stored  in  the  memory.     The 
capacity  is  an  *  innate/  a  nutritional  character ;  the  acquirements 
arise  under  the  stimulus  of  experience.     Thus  a  man  may  have 


422  NATURE  AND  NURTURE 

exceptional  mathematical  ability  by  means  of  which  he  achieves 
considerable  mathematical  learning  if  afforded  the  opportunity. 
The  ability  is  *  inborn  '  and  tends  to  be  '  inherited  '  by  offspring  ; 
the  acquirements  are  not.  That  is,  the  child,  if  he  lives  and  grows 
at  all,  is  sure  to  have  food  and  therefore  to  develop,  unless  he  has 
varied,  the  parental  capacity ;  but  he  is  not  sure  to  have  the 
parental  training,  the  nurture  of  the  same  use.  Therefore,  even  if 
he  'inherits'  the  parental  ability,  the  child  of  a  great  mathe- 
matician may,  or  may  not,  achieve  similar  distinction.  But  such 
a  one  is  more  likely  than  the  child  of  an  ignoramus,  not  only  to 
inherit  ability,  but  to  receive  the  right  training.  Without  the 
training  the  ability  is  naught ;  just  as  without  coal  the  engine  is 
naught.  Nutriment,  therefore,  bestows  on  the  child  the  parental 
aptitudes ;  association  with  the  parent  tends  to  bestow  the 
parental  acquirements.  Consequently  children  tend  to  resemble 
their  parents  for  a  double  reason ;  first,  because  they  tend  to  have 
much  the  same  capacities,  and  second,  because  they  make  much 
the  same  acquirements.  We  must  bear  in  mind,  however,  that  the 
parent  is  not  the  only  influence  in  the  child's  environment. 
Therefore,  not  only  may  the  child  vary  from  the  parent  in  capacity, 
but  also  he  may  differ  in  acquirements. 

695.  Mathematical  efficiency  depends  on  mathematical  acquire- 
ments made  by  virtue  of  mathematical  capacity  and  in  response 
to  mathematical  experience.  The  efficiency  is  impossible  without 
the  acquirements,  and  the  acquirements  without  both  the  capacity 
and  the  experience.  The  same  is  true  of  all  other  intellectual  char- 
acters. But  the  part  played  in  the  creation  of  efficiency  by 
capacity  on  the  one  hand,  and  by  experience  on  the  other — by 
nutriment  on  the  one  hand  and  use  on  the  other — varies  with 
different  characters  and  in  different  species.  The  caterpillar 
apparently  owes  nothing  to  acquirement ;  he  has  no  substratum  of 
capacity  wherewith  to  store  experience  and  therefore  cannot 
utilize  it.  The  acquirements  of  the  cat,  for  example  the  increased 
efficiency  in  hunting  which  practice  bestows,  are,  as  a  rule,  nothing 
more  than  mere  extensions  of  pre-existing  instincts  comparable  to 
those  extensions  of  its  physical  structures  which  are  bestowed  by 
use.  Some  of  man's  acquirements  are  also  mere  extensions  of 
instincts.  Thus,  both  parental  and  sexual  love  tend,  within  limits, 
to  be  increased  by  association  with  the  objects  of  affection. 
Speech  is  an  extension  of  the  infant's  tendency  to  utter  useful 
but  inarticulate  cries.  In  this  case,  however,  the  extension  is  im- 
measurably greater  than  the  thing  extended.  But  unlike  extensions 


INSTINCT  AND  ACQUIREMENT  423 

of  instinctive  actions  and  unlike  his  physical  acquirements,  most 
of  man's  intellectual  characters  cannot,  except  through  very 
strained  interpretations,  be  regarded  as  extensions  of  previously 
existing  innate  characters.  Thus  many  of  his  manual  dexterities, 
his  efficiency  in  reading,  his  devotion  to  a  religion,  or  an  ethical 
code,  resemble  nothing  instinctive  in  him.  They  are  wholly 
'  acquirements.' 

696.  We  must  distinguish  not  less  sharply  between  instinct 
and   acquirement,    than  between   capacity  and   acquirement.     A 
glance  at  the  literature  of  the  subject  demonstrates  that  numbers 
of  human  characters  are  accepted  as  innate  on  inadequate  evidence. 
Modesty  is  supposed  to  be  innate.     But  what  kind  of  modesty  ? 
that  of  the  Mohammedan  women,  or  that  of  the  nun,  or  that  of 
the  savage  ?     Savage  women  have  no  modesty  in  the  European 
sense,  but  I  have  known  mission  natives  exhibit  an  extraordinary, 
and,  as   it   seemed  to    me  an   Englishman,  an  absurd  degree   of 
prudishness.     In  Tonga,  for   untold    centuries,  the   natives  went 
about  naked  and  unashamed,  and,  judged  by  English  standards, 
sexual  intercourse  amongst  them  was  almost  promiscuous.     A  few 
years  later  mere  flirtation  was  regarded  as  a  horrible  crime  and 
was  legally  punishable.     It  is  impossible  to  doubt  that  English 
women  trained  by  savages  would  show  no  trace  of  the  traditional 
modesty  of  their  race.     Modesty  is  not  an  instinct,  but  an  acquire- 
ment dependent  on  memory.     The  only  instinct  with  which  it  is 
connected  is  that  of  imitation.     Morality  also  is  supposed  to  be  an 
instinct.     But   what   kind  of    morality?     Like   modesty,   morals 
vary  with   time   and  place.     Real  instincts  are  universal  in  the 
species,  and  in  measurable  time  unchanging.     We  often  read  of 
the  special   instincts   of  savages,   for  example   their  instinct   for 
tracking  game.     But  no  savage,  having  all  the  while  no  notion  of 
the  aim  or   end  of  his  actions,  has  an  innate  impulse  to  follow 
certain  marks  on  the  ground  till  he  catches  a  kangaroo  or  a  deer. 
Manifestly   his  so-called  instincts  are  acquirements.     He  excels 
the  civilized  man  for  the  same  reason  that  the  native  Frenchman 
excels  the  foreign  resident  in  the  perfection  of  his  French — because* 
he  has  learned  at  the  most  receptive  age. 

697.  Even  characters  which  have  a  large  instinctive  element 
are  extended,  modified  or  even  in  some  cases  in  a  sense  suppressed 
in  the   human   being    by  acquirement.     Appreciation   of  sexual 
beauty  is  an   instinct,   but  the  kind  of  beauty  admired  depends 
greatly  on   acquirement.     As  a  rule  we  admire  women  who  are 
decorated   in   the   latest   fashion.     At    the   present   day   we   can 


424  NATURE  AND  NURTURE 

perceive  no  element  of  beauty  in  the  chignon  or  crinoline  of  the, 
as  it  seems  to  us,  terribly  inartistic  Victorian  era ;  but  our  fathers 
were  ravished  by  the  appearance  of  the  women  who  wore  them. 
Various  savages  admire  mutilations  which  are  horrifying  to  us. 
Indeed  almost  all  races  practise  some  form  of  mutilation  and  find 
it  beautiful  ;  thus  we  crop  and  shave  the  magnificent  human 
mane  which,  judging  from  its  great  evolution,  must  have  been  a 
principal  instrument  of  fascination  amongst  our  remote  ancestors. 
I,  personally,  am  nauseated  by  the  sight  of  long  hair  on  a  male 
human  head.  Doubtless  sexual  jealousy  is  in  a  measure  in- 
stinctive ;  yet  while  the  husband  is  jealous  of  the  lover,  the  latter 
is  seldom  jealous  of  the  former  ;  were  the  emotion  purely  in- 
stinctive they  should  be  equally  jealous.  The  jealousy  of  an 
Australian  black  is  as  nothing  compared  to  that  of  the  Mohamme- 
dan. Parental  affection  is  an  instinct,  yet  many  people  have 
cheerfully  practised  infanticide  ;  and  the  average  parents  of  various 
races  are  good  or  bad  according  to  the  prevailing  fashion. 
Perhaps  the  most  convincing  evidence  that  parental  actions  are 
mainly  founded  on  acquirement  is  afforded  by  the  fact  that 
civilized  parents  whenever  possible  tend  to  delegate  them  to  the 
hands  of  servants.  The  actions  to  which  they  are  prompted  by 
purely  instinctive  impulses,  for  example  thirst,  hunger,  weariness, 
and  sexual  love  are  never  delegated. 

698.  To  sum  up :  the  distinguishing  peculiarity  of  the  human 
being  as  compared  to  other  animals  is  that  his  characters  arise 
much  less  under  the  stimulus  of  nutriment  and  much  more  under 
that  of  use.  Most  of  his  nutritional  characters  are  mere  foundations 
on  which  '  acquirements '  are  reared.  Biologists  commonly  suppose 
that  innate  characters  are  much  more  important  than  acquirements. 
But  if,  were  it  possible,  we  deprived  an  adult  human  being  of  his 
acquirements  nothing  would  be  left  but  the  likeness  of  a  new  born 
infant  which  possessed  the  sexual  instinct,  and  a  few  adult  physical 
traits  such  as  hair,  teeth,  external  ears,  and  organs  of  generation. 
Manifestly  the  physical  and  mental  maturity  of  the  normal  human 
being  depends  mainly  on  acquirements,  the  making  of  which  is 
just  as  essential  a  part  of  adult  development  as  the  growth  of  heart 
and  limbs  is  of  fcetal  development.  This  truth,  though  opposed  to 
scientific  tradition  and  on  that  account  rarely  recognized,  is  really 
a  matter  of  common  knowledge  and  is  so  plainly  true  that  I  think 
it  has  only  to  be  formally  stated  to  be  recognized  as  true.  It 
may  be  that  there  is  more  of  what  is  innate  and  less  of  what  is 
acquired  in  this  or  that  human  character  than  I  have  been  led  to 


THE  MIND  OF  THE  IDIOT  425 

believe.  But  the  fact  that  human  acquirements,  especially  mental 
acquirements,  are  of  immensely  greater  magnitude  and  importance 
than  is  commonly  supposed  cannot,  I  believe,  be  doubted. 

699.  A  little  thought  renders  it  evident  that  the  essential  defect 
of  the  feeble-minded  person,  the  idiot,  and  the  imbecile,  is  lack  of 
memory.1     He  is  unable  to  profit  like  the  normal  individual  from 
experience.     This  defect  of  memory  may  be,  and  usually  is,  general, 
so  that  the  individual  is  able  to  learn  very  little.     Or  the  defect 
may  be  limited  to  some  particular ;  for  example  the   individual 
may  be  unable  to  acquire  the  code  of  morals  prevalent  in  the 
community   in   which   he   exists — an  acquirement  which  on  the 
average  and  in  the  long  run  would  be  of  great  advantage  to  him. 
The  truth  that  the  higher  intellectual  faculties  are  less  developed 
in  the  feeble-minded  than  lower  faculties  is  due  entirely  to  the  fact 
that  the  former  can  be  acquired  only  by  people  whose  receptive 
powers  are  considerable.     In  effect  and  in  fact  the  feeble-minded 
person  is  an  instance  of  reversion  to  a  pre-human  mental  state. 
Judged    by  the  human  standard  every   dog  and   monkey  is  an 
imbecile.     But  the  reversion  of  the  imbecile  is  not  complete ;  for, 
while  he  has  lost  part  of  his  power  of  profiting  by  experience,  he  has 
regained  no  part  of  the  lost  power  of  being  guided  by  instinct. 
Therefore  he  is  correspondingly  helpless  as  compared  to  a  lower 
animal.     On  the  other  hand,  the  instincts  (e.g.  the  sexual)  which 
normal  human  beings  still  possess  often  appear  unduly  prominent 
in  him  ;  but  only  because  he  cannot  learn  to  control  them. 

700.  But   though   human  beings    develop   mainly   under   the 
stimulus  of  use  and  experience,  doubtless  they  differ 'by  nature ' 
amongst  themselves  just  as  much  as  animals  that  develop  solely 
under  the  stimulus  of  nutriment.     In  the  last  analysis  all  variations 
are   nothing   other   than   variations  in  powers  of  responding   to 
stimuli — nutriment,  use,  and  injury — and  we  have  no   reason  to 
suppose  that  variations  in  the  capacities  for  responding  to   the 
stimulus  of  use  are  smaller  or  fewer  than  variations  in  the  capacity 
for  responding  to  the  stimulus  of  nutriment  or  injury.     Doubtless, 
therefore,  men  vary  not  only  in  general  mental  capacity  (i.e.  power 
of  making  mental  acquirements)  but  also  in  particular  departments 
of  capacity.     At  the  one  extreme  is  the  absolute  idiot  who  has  no 
power  of  storing  and  utilizing  experiences,  and,  at  the  other,  the 
genius  who  has  exceptionally  great  powers.     It  has  been  observed 
that  some  imbeciles  have  considerable  capacity  in  some  particular 
department.     Thus,  they  may  have  great  powers  of  remembering 

1  See  §§  762  et  seq. 


426  NATURE  AND  NURTURE 

this  or  that  class  of  facts,  but  no  power  of  learning  to  utilize  them. 
So  also,  while  it  is  possible  that  some  geniuses  may  be  men 
endowed  with  exceptional  all-round  capacity,  they  are  usually 
distinguished  from  the  average  type  by  exceptional  capacity  in 
some  particular  department  of  mental  activity.  It  is  probable,  for 
example,  that  Shakespeare  had  more  poetic  capacity  (i.e.  power  of 
responding  to  poetic  experiences,  of  recording  and  learning  to 
utilize  such  experiences)  and  less  artistic  capacity  than  Michael 
Angelo,  who  presumably  had  less  mathematical  capacity 
than  Newton,  who  in  turn  had  less  military  capacity  than 
Napoleon,  who  again  was  inferior  in  philosophic  capacity  to 
Darwin. 

701.  But,  admitting  all  this,  it  must  still  be  borne  in  mind  that 
(i)  the  stimulus  of  nutriment  is  capable  of  developing  the  bodies 
and  minds  of  men  in  only  one  way  ;  that  is,  we  cannot  by  changing 
the   kind   of  nutriment   which   the   human  being   is   capable   of 
assimilating,  produce  different  kinds  of  bodies  and  minds ;  under 
all  kinds  of  nutriment  a  man  will  still  have  much  the  same  sort  of 
limbs,  lungs,  sensations,  instincts,  and  memory ;  (2)  changes  in  the 
kind  of  stimulus  of  use  cannot  produce  very  great  changes  in  the 
bodies  of  men ;  as  in  the  case  of  nutriment,  they  may  develop 
this  or  that  organ  more  or  less  according  to  the  amount  of  use 
supplied,  but  that  is  all ;  limbs  and  lungs  and  other  structures  will 
still  be  of  the  same  kind  no   matter  what  the  stimulus ;  (3)  but 
differences  in  the  stimulus  of  experience  supplied  to  the  mind  are 
capable  of  causing  tremendous  differences  in  mental  development. 
For  example,  while  the  bodily  parts  of  a  yokel  (e.g.  his  brain) 
differ  little  in  appearance  from  that  of  a  cultured  man,  the  mental 
difference  is  obviously  very  great.     It  follows,  that  in  comparing  men 
or  races  we  are  on  safer  ground  when  we  suppose  that  their  bodily 
differences  are  innate  (i.e.  germinal)  than  when  we  suppose  that 
their  mental  differences  are  innate.     Doubtless,  as  I  say,  differences 
in  mental  capacity  are  just  as  great  as  innate  physical  differences ; 
but  they  are  apt  to  be  overshadowed  and  concealed  by  vaster 
acquired  differences. 

702.  Perhaps  the  most  convincing  evidence  that  human  mental 
and  moral  characters  arise  mainly  under  the  stimulus  of  experi- 
ence is  afforded  by  the  history  of  races  and  nationalities.     Like 
individuals,  races  differ  in  their  mental  characteristics.     Thus  the 
English  have  one  set  of  characteristics,  (knowledge,  ideals,  and 
so  forth),  the  Japanese  a  second,  the  Russians  a  third,  and  West 
Coast  Africans  a  fourth.     Most  historians  and  men   of  science 


RACIAL  MENTAL  CHANGES  427 

adopt  the  easy  view  that  the  mass  of  these  differences  are  innate 
in  the  same  sense  that  physical  differences  are  innate. 

703.  Man  is  a  very  slow  breeding  animal.     Innate  changes  of 
importance  cannot  occur  in  his  race  at  all  swiftly — in  the  course  of 
a  few  centuries — except  under  excessively  stringent  selection  ;  and, 
owing  to  the  strong  tendency  to  retrogression  thereby  created,  such 
changes  can  only  be  maintained  afterwards  by  selection  almost  as 
stringent   and   continued  over   a  very  long  period.     But,  in   the 
absence  of  all   recognisable  selection,  some   races  have  changed 
their  mental  characteristics  with  great  rapidity.     Thus  the  Greeks 
and  Romans,  separating  quickly  from  the  surrounding  barbarians, 
displayed,  for  a  few  centuries,  extraordinary  intellectual  qualities, 
and  then  sank,  quite  as  suddenly,  into  abysmal  degradation.     At 
the  Renaissance  and  the  Reformation,  after  more  than  a  thousand 
years  of  stagnation,  various  European  nations  began  to  display 
qualities  comparable  to  those  of  the  great  Pagans.     Their  material 
and  intellectual  progress  has  continued  to  the  present  day ;    but 
even  now,  when  we   are   able   to  watch   contemporaries,  we   are 
unable  to  detect  any  form  of  stringent  selection  save  that  by 
disease.     The  Japanese  furnish  a  very  striking  modern  instance. 
Another  similar  instance  is  afforded  by  the  fact  that,  in  a  single 
generation,  the  ferocious  cannibals  of  New  Zealand  have  become 
progressive  and  law-abiding.     Nothing  apparently  prevents  them 
taking  an  equal  place  with  the  whites  as  citizens  of  a  progressive 
and  civilised  state   except   their   physical   inability  to  withstand 
imported  disease. 

704.  Every  race  that  has  changed  its  religion  has  immediately 
undergone  a  great  moral  and  intellectual  change.     The  inhabitants 
of  Syria   and  North  Africa   are   examples.     At   first   they  were 
Pagans  and  shared  to  some  extent  the  Greek  and  Roman  character- 
istics ;  next  they  became  typical  Christians  of  the  Dark  Ages ; 
lastly    they    became    typical    Mohammedans, — fierce,    turbulent, 
fanatical,  stagnant.     Races  of  diverse  origin,  which  follow  a  given 
religion,  resemble  one  another  more  closely  in  mental  characteristics 
than    sections  of  the   same   race  which   follow  diverse   religions. 
Thus   all   Mohammedan   nationalities   have   mental    peculiarities 
which  separate  them  sharply  from  Christians  on  the  one  hand  and 
Pagans  on  the  other.     Mohammedan  Greeks  mentally  resemble 
their   co-religionists  more   nearly   than    their   compatriots.      The 
Teutonic  Catholics  of  Ireland  are  quite  indistinguishable  from  the 
Celtic  Catholics,  but  they  differ  sharply  from  Protestant  Teutons. 
Catholic  negroes  are  typical  Catholics  of  the  more  ignorant  type  ; 


428  NATURE  AND  NURTURE 

the  negro  Baptists  and  Methodists  of  the  United  States  are  in 
many  respects  typical  Baptists  and  Methodists  resembling  those 
of  Wales.  Jews  who  abide  by  their  religion  retain  their  character- 
istics ;  those  who  abandon  it  merge  indistinguishably  into  the 
surrounding  population.  Indeed  all  the  world  over  peoples  of  the 
same  colour  are  divided  mentally  much  more  sharply  by  religious 
differences  than  by  anything  else. 

705.  To  me  it  appears,  if  only  we  think  carefully  enough  and 
take  all  the  facts  into  account,  that  it  is  impossible  to  come  to 
conclusions  other  than  the  foregoing.     They  amount  to  nothing 
more  than  is  implied  in  the  statement  that  man  is  mentally  an 
extremely    adaptable,    malleable,   educable,   intelligent,   and    in- 
tellectual animal ;  and,  therefore,  that  he  is  much  more  a  creature 
of  habit   than  of  instinct.     Educability  is  nothing  other  than  a 
power   of  growing  mentally  under   the   stimulus  of  experience ; 
intellectuality  is  nothing  else  than  a  having  so  grown. 

706.  Some     authorities,    however,    founding     themselves    on 
statistical  inquiries,  are  of  a  contrary  opinion.     At  least  they  claim 
to  have  proved  that  man  is  less  educable,  less  a  creature  of  acquire- 
ment, than  I    have   supposed.      Thus    Professor   Karl    Pearson1 
issued  schedules  to  school-teachers  and  requested  them  to  supply 
information  as  precise  as  possible  concerning  certain  mental  and 
physical  characters  of  (i)  pairs  of  brothers,  (2)  of  sisters,  and  (3)  of 
brother  and  sister.     Some  of  the  physical  characters  were  capable 
of  being  measured.     Others  were  estimated,  as,  of  course,  were  all 
mental   characters.      The   physical    characters    included    health, 
athleticism,  length,  breadth,  and  height  of  head,  colour,  smooth- 
ness, waviness,  or  curliness  of  hair,  and  colour  of  eyes  ;  the  mental 
characters  included  ability  in  various  studies,  noisiness  or  quiet- 
ness, self-consciousness,  self-assertion,  shyness,  conscientiousness, 
popularity,  and  temper.     Pearson  chose  children  rather  than  adults 
owing  to  the  difficulty  of  obtaining  correct  information  concerning 
the  latter.     "  In  the  first  place  it  seemed  to  me  absolutely  impos- 
sible to  get  a  quantitative  measure  of  the  resemblances  in  moral 
and  mental  characters  between  parent  and  offspring.     You  must 
not  compare  the  moral  character  of  a  child  with  those  of  its  adult 
parents.     You   can  only  estimate  the  resemblance  between   the 
child  and  what  its  parents  were  as  children.     Here  the  grand-parent 
is  the  only  available  source  of  information  ;  but  not  only  does  age 

1  "  On  the  Inheritance  of  the  Mental  and  Moral  characters  in  Man,  and  its 
Comparison  with  the  Inheritance  of  the  Physical  characters."  The  Huxley  Lecture 
for  1903.  The  Anthropological  Institute  of  Great  Britain  and  Ireland. 


BIOMETRY  429 

affect  the  clearness  of  memory  and  judgment,  the  partiality  of  the 
relative  is  a  factor  which  can  hardly  be  corrected  and  allowed 
for."  *  He  argued  that  resemblances  between  children  of  the  same 
family  is  as  clear  a  proof  of  inheritance  as  resemblance  between 
parent  and  child — in  which,  doubtless,  he  is  right. 

707.  It  was  found  that,  on  the  average,  the  children  of  the 
same  family  resembled  one  another  as  closely  mentally  as  physic- 
ally.    Pearson  admits  that  certain  physical  characters  such  as  size 
of  head  and  body  are  influenced  by  *  nurture,  food,  and  exercise,' 
but  since  brothers  and  sisters  resemble  one  another  in  these  traits 
in  the  same  degree  as  in  such  physical  characters  as  the  cephalic 
index,  and  the  colour  of  hair  and  eye,  which  are  not  affected  by 
*  home  influence,'  he  concludes  that  the  environment  is  not  a  dis- 
turbing factor  when  calculations  are  made  respecting  the  degree  of 
resemblance  due  to  inheritance.      A  similar  line  of  reasoning  is 
applied  to  mental  characters.     In  effect  his  conclusion  amounts  to 
this — that  if,  as  regards  any  set  of  characters,  brothers  and  sisters 
resemble  one  another  on  the  average  in  the  same  degree,  then  all 
the  resemblances  must  be  due  to  the  same  cause.     For  example,  if 
the  resemblances  are  equal  as  regards  geniality,  probity,  eye-colour, 
hair-colour,  and  the  cephalic  index,  then   geniality  and    probity 
must  be  inherited   in  the  same  sense  as  the  physical  characters 
mentioned.     "  The  sameness  surely  involves  something  additional. 
//  involves  a  like  heritage  from  parents.     The  degree  of  resemblance 
between  children  and  parents  for  the  physical  characters  in  man 
may  be  applied  to  the  degree  of  resemblance  between  children 
and  parents  for  psychical   characters.     We   inherit   our   parents' 
tempers,  our  parents'  conscientiousness,  shyness  and  ability,  even 
as  we  inherit  their  stature,  fore-arm  and  span."  z 

708.  But   eye-colour   cannot   be    influenced   by   environment, 
whereas  there  is  at  least  some  reason  to  believe  that  geniality  and 
probity  may  be  so  influenced,  and  the  environment  of  different 
families  differs  greatly.     Pearson  meets  this  difficulty  by  the  state- 
ment that  "  We  are  too  apt  to  overlook  the  possibility  that  the 
home  standard  is  itself  a  product  of  parental  stock,  and  that  the 
relative  gain  from  education  depends  to  a  surprising  degree  on  the 
raw  material  presented  to  the  educator.     We  are  agreed  that  good 
homes  and  good  schools  are  essential  to  national  prosperity.     But 
does  not  the  good  home  depend  on  the  percentage  of  innately  wise 
parents,  and    the    good    school  depend  quite   as    much    on    the 
children's  capacity,  as  on  its  staff  and  equipment?"3     According 

1  P.  1 80.  *  Loc.  cit.t  p.  204.  8  Loc.  cit.y  pp.  179,  180. 


430  NATURE  AND  NURTURE 

to  Pearson,  then,  there  must  be,  on  the  average,  a  tremendous 
germinal  difference  between  Englishmen  of  the  upper  classes  and 
those  of  the  lower,  between  Englishmen  of  the  country  and  those 
of  the  town,  between  Englishmen  of  to-day  and  those  of  a  century 
or  two  ago,  between  Englishmen  and  foreigners,  between  Greeks 
and  Romans  of  the  period  of  national  greatness  and  their  immedi- 
ate predecessors  and  successors,  between  Greek  Mohammedans  and 
Greek  Christians,  and  so  forth ;  and  an  English  child  reared  by 
African  cannibals  should  develop  the  moral  and  intellectual  as  well 
as  the  physical  characteristics  of  his  progenitors  not  of  his  educators. 
709.  Moreover,  "  If  the  conclusion  we  have  reached  to-night  be 
substantially  a  true  one,  and  for  my  part  I  cannot  for  a  moment 
doubt  that  it  is  so,  then  what  is  its  lesson  for  us  as  a  community  ? 
Why  simply  that  geniality  and  probity  and  ability  may  be  fostered 
indeed  by  home  environment  and  by  provision  of  good  schools  and 
well  equipped  institutes  for  research,  but  that  their  origin  like  health 
and  muscle,  is  deeper  down  than  these  things.  They  are  bred,  not 
created.  That  good  stock  breeds  good  stock  is  a  common-place 
of  every  farmer ;  that  the  strong  man  and  woman  have  healthy 
children  is  widely  recognized  too.  But  we  have  left  the  moral  and 
intellectual  faculties  as  qualities  for  which  we  can  provide  amply 
by  home  environment  and  sound  education." l  .  .  .  "  Looking 
round  dispassionately  from  the  calm  atmosphere  of  anthropology, 
I  fear  there  really  does  exist  a  lack  of  leaders  of  the  highest 
intelligence,  in  science,  in  the  arts,  in  trade,  even  in  politics.  I 
do  seem  to  see  a  want  of  intelligence  in  the  British  merchant,  in 
the  British  professional  man  and  in  the  British  workman.  But  I 
do  not  think  the  remedy  lies  solely  in  adopting  foreign  methds  of 
instruction  or  in  the  spread  of  technical  education.  I  believe  we 
have  a  paucity,  just  now,  of  the  better  intelligences  to  guide  us 
and  of  the  moderate  intelligences  to  be  successfully  guided.  The 
only  account  we  can  give  of  this  on  the  basis  of  the  results  we  have 
reached  to-night  is  that  we  are  ceasing  as  a  nation  to  breed 
intelligence  as  we  did  fifty  or  a  hundred  years  ago.  The  mentally 
better  stock  in  the  nation  is  not  reproducing  itself  at  the  same 
rate  as  it  did  of  old ;  the  less  able,  and  the  less  energetic  are 
more  fertile  than  the  better  stocks.  No  scheme  of  wider  and 
more  thorough  education  will  bring  up  in  the  scale  of  intelligence 
hereditary  weakness  to  the  level  of  hereditary  strength.  The  only 
remedy,  if  one  be  possible  at  all,  is  to  alter  the  relative  fertility  of 
the  good  and  bad  stocks  in  the  community.  Let  us  have  a  census 

1  Loc.  cit.,  p.  306. 


BIOMETRY  431 

of  the  effective  size  of  families  among  the  intellectual  classes  now 
and  a  comparison  with  the  effective  size  of  families  in  the  like 
classes  in  the  first  half  of  the  last  century.  You  will,  I  feel  certain, 
find,  as  in  the  case  of  recent  like  censuses  in  America,  that  the 
intellectual  classes  are  now  scarcely  reproducing  their  own 
numbers,  and  are  very  far  from  keeping  pace  with  the  total  growth 
of  the  nation.  Compare  in  another  such  census  the  fertility  of  the 
more  intelligent  working  man  with  that  of  the  uneducated  hand 
labourer.  You  will,  I  again  feel  certain,  find  that  grave  changes 
have  taken  place  in  relative  fertility  during  the  last  forty  years. 
We  stand,  I  venture  to  think,  at  the  commencement  of  an  epoch 
which  will  be  marked  by  a  great  dearth  of  ability.  If  the  views  I 
have  put  before  you  to-night  be  even  approximately  correct,  the 
remedy  lies  beyond  the  reach  of  revised  educational  systems  ;  we 
have  failed  to  realize  that  the  psychical  characters,  which  are,  in 
the  modern  struggle  of  nations,  the  backbone  of  state,  are  not 
manufactured  by  home,  school  and  college  ;  they  are  bred  in  the 
bone;  and  for  the  last  forty  years  the  intellectual  classes  of 
the  nation,  enervated  by  wealth  or  love  of  pleasure,  or  follow- 
ing an  erroneous  standard  of  life,  have  ceased  to  give  us  in  due 
proportion  the  men  we  want  to  carry  on  the  ever-growing  work 
of  our  empire,  to  battle  in  the  fore-rank  of  the  ever  intensified 
struggle  of  nations. 

710.  "  Do  not  let  me  close  with  so  gloomy  a  note.     I  do  not 
merely  state  our  lack.     I  have  striven  by  a  study  of  the  inheri- 
tance of  mental  and  moral  characters  in  man  to  see  how  it  arises, 
and  to  know  the  real  source  of  an  evil  is  halfway  to  find  a  remedy. 
That  remedy  lies  first  in  getting  the  intellectual  section  of  our 
nation  to  realize  that  intelligence  can  be  aided  and  can  be  trained, 
but  no  training  or  education  can  create  it.     You  must  breed  it, 
that  is  the  broad  result  for  statecraft  which  flows  from  the  equality 
in  inheritance  of  the  psychical  and  physical  characters  in  man."  l 

711.  Pearson   adopts  the  ordinary   view  that   the   body   and 
mind  of  the  individual  are  compounded  of  '  innate '  and  '  acquired  ' 
characters,  that  only  the  former  tend  to  be   *  inherited/  and,  there- 
fore, that  evolution  (or  any  sort  of  intrinsic  racial  change)  depends 
entirely  on  them,  acquirements  being  mere  somatic  '  modifications.' 
On  the  other  hand,  the  view  upheld  by  me  has  been  that  no  kinds 
of  characters  are  more  innate  or  inheritable  than  any  other  kind, 
that  the  terms  '  innate '  and  '  acquired '  are  misnomers  and    the 
causes  of  endless  confusion,  misunderstanding,  and  misinterpretation, 

1  Loc.  cit.,  pp.  206-7. 


432  NATURE  AND  NURTURE 

that  the  so-called  innate  characters  are  simply  characters  which 
have  developed  under  one  kind  of  stimulus  (that  of  nutriment) 
whereas  the  so-called  acquirements  are  equally  important  characters 
which  have  developed  under  other  kinds  of  stimuli  (those  of  injury 
and  use),  that  all  evolution  (or  any  sort  of  intrinsic  racial  change) 
consists  in  a  germinal  alteration  which  implies  increased  or 
decreased  capacity  to  develop  in  a  definite  way  under  the  influence 
of  this  or  that  stimulus.  According  to  this  view  the  superior 
innateness  and  inheritability  of  nutritional  characters  are  only  in 
seeming.  They  develop  more  certainly  than  acquirements  merely 
because  the  stimulus  of  nutriment  is  always  present  in  every 
individual  who  develops  at  all,  whereas  the  stimulus  under  which 
this  or  that  acquirement  arises  may  be  absent.  Moreover,  I  have 
supposed,  not  only  that  the  evolution  of  the  higher  animals  has 
consisted  mainly  in  a  continually  increasing  power  of  developing 
under  the  stimulus  of  use,  but  also  that  it  has  consisted  in  a  con- 
currently decreasing  power  of  developing  under  the  stimulus  of 
nutriment — the  former  power  possessing  great  advantages  over, 
and  therefore  displacing  the  latter. 

712.  Of  all  this  evolution,  which  to  me  appears  to  be  so  mani- 
fest, Pearson  seems  unaware.     As  results  of  our  differing  opinions, 
the  moral  and    intellectual  characters   are   to  Pearson   instincts ; 
whereas   I  cannot  conceive  how  such  characters  can  be  instincts. 
An  instinct,  as  I  understand  it,  is  merely  an  emotional  impulse,  the 
prompting  of  which  the  individual  is  sure  to  follow  unless  it  is 
opposed  by  other  instincts  or  acquirements.     It  is  utterly  unintelli- 
gent, utterly  non-moral.     It  has  nothing  to  do  with  thought  except 
as  a  subject  of  thought,  or  with  a  sense  of  right  and  wrong  except 
in  so  far  as  this  sense  approves  or  disapproves  of  its  promptings. 
Moral  and  intellectual  characters,  as  proved  by  unlimited  evidence 
and  from  their  very  nature,  are  acquirements.     Taking  all  the  facts 
into  account,  I  cannot  imagine  a  purely  instinctive  animal,  a  beetle 
or  a  caterpillar,  as  moral  or  intellectual,  or  a  human  being  as  such 
except  by  virtue  of  the  characters  supplied  by  his  memory.  In  effect, 
the  moral  and  intellectual  beings  that  Pearson  imagines,  since  they 
are  not  moral  or  intellectual  through  acquirement,  are  imbeciles.1 

713.  The  differences  between    Pearson    and   me   are  so  great 
that  it  is  useless  to  discuss  details  in  this   place.     Directly   or 
indirectly  I  have  already  done  so,  supporting  my  own  opinion  in 
almost  every  chapter  of  the  present  volume  by  a  mass  of  evidence 
which  is  enormous,  and  which,  however  new  (or  newly  applied), 

1  See  §  699. 


THE  INHERITANCE  OF  MENTAL  TRAITS          433 

cannot,  I  think,  be  controverted.1  As  far  as  I  am  able  to  judge,  I 
have  drawn  no  illegitimate  inferences.  Pearson's  reasoning,  in  the 
very  cases  which  he  instances,  appears  to  me  demonstrably  wrong. 
His  main  inference  is  that,  since  offspring  resemble  one  another  in 
the  same  degree  in,  for  example,  probity  and  eye-colour,  therefore 
these  characters  are  both  '  innate.'  But,  if  his  reasoning  is  valid 
as  regards  the  mental  and  physical  characters  named  by  him,  it 
should  be  valid  also  as  regards  other  characters  not  named.  Now 
English  school  children  resemble  one  another  absolutely  in  that 
they  all  possess  heads,  lungs,  livers,  and  so  forth.  Here  the  degree  of 
resemblance  is  '  unity.'  They  reproduce  these  characters  with  much 
greater  certainty  than  eye  and  hair-colour  and  variations  in  fore- 
arm and  span.  They  also  resemble  one  another  absolutely  in  that, 
when  they  have  reached  a  certain  age,  they  can  all  read,  write,  and 
speak  the  English  language,  and  in  that  they  have  English  notions 
of  modesty  with  respect  to  clothes.  Here,  again,  the  degree  of 
resemblance  is  roughly  '  unity.'  At  any  rate  they  reproduce  these 
characters  with  much  greater  certainty  than  they  do  eye-colour  and 
the  like.  Moreover,  in  the  case  of  the  boys,  there  is  a  mental  tendency, 
almost  as  universal  as  their  sex,  to  wear  trousers ;  in  the  case  of 
the  girls,  to  wear  frocks.  The  children  would  be  infinitely  reluctant 
to  appear  at  school  without  these  garments.  Must  we  suppose, 
then,  that  this  sameness  involves  a  like  heritage,  a  similarity  of  the 
germ-plasm,  and  that  English  children  '  inherit '  these  characters, 
which  are  universally  regarded  as  acquirements  and  would  probably 
be  admitted  as  such  by  Pearson,  with  a  degree  of  certainty  which 
is  almost  as  great  as  that  with  which  they  inherit  heads,  livers,  and 
sexual  organs  ?  I  do  not  mean  in  the  least  to  be  offensive  in  the 
examples  I  have  drawn.  I  have  selected  them  merely  in  order  to 
indicate  as  strongly  and  vividly  as  possible  the  reasons  that  have 
led  me  to  think  that  Pearson's  thinking,  founded  as  it  is  solely  on 
biometric  data,  though  much  more  massive  and  conclusive  evidence 
is  available,  and  quite  untested  as  it  is  by  any  appeal  to  reality,  is 
totally  mistaken  and  illegitimate.  Biometry  is  capable  of  demon- 
strating the  degrees  in  which  given  characters  tend  on  the  average  to 
be  reproduced  by  offspring  under  given  conditions.  But,  if  we  wish 
to  ascertain  the  category  to  which  any  of  these  characters  belongs 
— whether  it  is  *  inborn '  or  *  acquired ' — we  must  draw  an  inference 
which  biometry,  a  mode  of  observing  not  of  thinking,  cannot  help 
us  to  draw  ;  and  which,  therefore,  must  be  tested  as  carefully  as 
when  our  facts  have  been  otherwise  gathered. 

1  See  also  chapter  xxv. 
28 


434  NATURE  AND  NURTURE 

714.  When  we  compare  one  modern  species  with  another,  the 
more   intelligent  type  invariably  has,  proportionately  to  the  size 
of  its  body,  a  larger  brain.     Thus  the  dog  has  a  larger  brain  than 
a  rabbit,  and  a  man  than  a  dog.     Presumably,  therefore,  intelli- 
gence and  size  of  brain  are  correlated  in  some   degree  at  least. 
Doubtless  the  correlation  is  not  absolute  ;  for  brains  vary  in  their 
constituent  elements,  for  instance,  in  the  relative  amounts  of  grey 
and  white  matter.     "  The  leading  feature  in  the  development  and 
separation  of  man  from  amongst  other  animals  is  undoubtedly  the 
relatively  enormous  size  of  the  brain  in  man  and  the  corresponding 
increase  in  its  activity  and  capacity.     It  is  a  very  striking   fact 
that  it  was  not  in  the  ancestors  of  man  alone  that  this  increase  in 
the   size   of  the   brain  took  place   at   the   same   period,  viz.  the 
Miocene.     The  great  mammals,  such  as  the  titanotherium,  which 
represented  the  rhinoceros  in  early  Tertiary  times,  had  a  brain 
which  was  in  proportion  to  the  bulk  of  the  body,  not  more  than 
one-eighth  of  the  volume  of  the  brain  of  the  modern  rhinoceros. 
Other  great  mammals  of  the  earlier  Tertiary  period  were  in  the 
same  case ;  and  the  ancestors  of  the  horse,  which  are  better  known 
than   those   of  any   other   modern   animal,   certainly   had    much 
smaller  brains  in  proportion  to  the  size  of  their  bodies  than  has 
their  descendant."1 

715.  Biometricians,     however,     founding     their     opinions    on 
statistical   data,   have   denied   that   the   law   that  intelligence   is 
correlated  to  size  of  brain  obtains  in  the  case  of  human  races  and 
individuals.     According  to  them  "  there  is  no  marked  correlation 
between  skull  capacity  and  intellectual  power."     What,  however, 
is  the  real  meaning  of  their  facts,  for  there  can  be  little  doubt  that 
the  facts  are  correct?     The  mind  manifestly   grows   under  the 
stimulus  of  experience.     Mental  facts   are  correlated  to  cerebral 
facts.     Therefore,  we  have  every  reason  to  believe  that  the  brain 
grows  under  the  stimulus  of  use.     We  know,  in  fact,  that  if  one 
hemisphere  of  the  brain  atrophies  from  any  cause,  such  as  disease, 
the  opposite  hemisphere  tends  to  hypertrophy ;    and   we  cannot 
account  for  this  increase  except  by  supposing  that  it  results  from 
increase  of  function.     After  birth,  then^the  growth  of  the  mind  and 
brain  is  conditioned,  on  the  one  hand,  by  the  inborn  capacity  to 
grow  under  the  stimuli  of  experience  and  use,  and  on  the  other,  by 
the  amount  of  stimulus.     Individuals  may  differ  both  with  respect 
to  the  capacity  and  the  amount  of  stimulus  their  minds  and  brains 
receive.     It  follows,  within  limits  that  vary  with  the  individual, 

1  The  Kingdom  of  Man,  by  Sir  Ray  Lankester,  p.  22. 


BRAIN  VOLUME  AND  MENTAL  CAPACITY         435 

that  the  growth  of  the  brain  after  birth  is  in  some  degree 
proportionate  to  the  extent  to  which  it  is  used.  But  the  degree  of 
intelligence  achieved  does  not  depend  solely  on  capacity  and 
amount  of  experience.  It  depends  also  on  the  kind  of  experience. 
An  individual  may  acquire  a  false  and  foolish  conception  of  his 
total  environment  with  as  much  toil  as  a  true  and  wise  one. 
Mediaeval  monks  had  on  the  average  larger  brains  than  their  con- 
temporaries, and  the  Chinese  as  a  race  have  larger  brains  than  most 
races,  but  it  does  not  follow  necessarily  that  they  were,  or  are,  more 
intelligent.  The  real  problem,  therefore,  is  not  whether  there  is  a 
correlation  between  skull  capacity  and  intellectual  power,  but  whether 
the  capacity  to  develop  a  large  brain  is  correlated  to  a  capacity  to 
become  exceptionally  intelligent  in  one  or  more  directions. 

716.  The  right  conclusion  to  which  the  biometric  facts,  com- 
bined with  the  rest  that  we  know,  lead  us,  appears  to  me,  not  that 
the  men  who  can  develop  large  brains  have  on  the  average  no 
greater  power  of  becoming  intelligent  than  men  who  can  only 
develop  small  brains,  but  that  the  former  may  be  worse  trained 
and  therefore  less  intelligent.  In  other  words,  the  biometrical 
facts  tend  to  demonstrate  that  right  mental  training  is  of  as  much 
importance  as  capacity. 


CHAPTER  XXIII 
PHYSICAL   DETERIORATION    AND  MICROBIC    DISEASE 

Summary — The  factors  in  development — Methods  of  improving  development 
— Human  selective  breeding — The  effects  of  diet — Of  exercise — Of  mental  training 
— Physical  deterioration — The  opinions  of  biometricians — Of  medical  men — The 
right  method  of  improving  the  physique  of  urban  populations — Microbic  diseases — 
External  and  internal  sanitation — Contagious,  water-borne,  insect-borne,  earth- 
borne,  and  air-borne  diseases. 


o 


717.  ^^\UR  study  of  heredity  from  the  purely  scientific  stand- 
point is  ended.  We  have  reached  certain  conclusions, 
certain  broad  principles, '  laws/  or, '  brief,  simple,  and 
comprehensive  classification  of  facts/  from  which  necessary  con- 
sequences may  be  deduced.1  No  characters  are  really  hereditary ; 
or,  if  the  term  be  admitted,  all  characters  are  equally  hereditary. 
Characters  differ,  not  because  some  are  inborn  and  inheritable  while 
others  are  acquired  and  not  inheritable,  but  because  they  arise 
under  different  classes  of  stimuli.  Evolution  is  only  another  name 
for  adaptation,  and  in  the  last  analysis  all  adaptation  results  from 
the  Natural  Selection  of  favourable  variations.  A  variation  is  due 
to  an  alteration  in  the  germ-plasm.  Variations  are  either  '  spon- 
taneous' or  due  to  the  direct  action  of  the  environment  on  the 
germ-plasm.  The  latter  class  of  variations  are  relatively  rare,  and 
can  very  seldom,  if  ever,  be  other  than  unfavourable.  Therefore 
Natural  Selection  builds  solely,  or  almost  solely,  on  spontaneous 
variations,  and  a  main  part  of  its  work  is,  on  the  one  hand,  to 
provide  for  the  occurrence  of  spontaneous  variations  and  regulate 
their  magnitude,  and,  on  the  other,  to  render  the  germ-plasm  in- 
susceptible to  the  direct  action  of  the  environment.  It  follows 
that  the  variability  of  species  and  characters  is  not  a  fixed  quantity ; 
on  the  contrary,  each  species  and  each  of  its  characters  tends  to  be 
variable,  on  the  average,  in  a  degree  best  suited  to  secure  adapta- 
tion. In  other  words,  the  tendency  to  vary,  displayed  by  all 
living  beings,  is  itself  an  adaptation  which  is  subject  to  variations, 
by  means  of  which  Natural  Selection  regulates  the  amount  of 
variability  and  provides  for  the  occurrence  of  variations  all  round 
1  See  §§  76  (footnote),  590,  819  et  seq. 


SUMMARY  437 

the  specific  mean.  It  follows  also  that  the  germ-plasm  of  every 
species  is  less  susceptible  to  the  direct  action  of  influences  to  which 
it  has  long  been  subjected  than  to  influences  of  which  it  has  had 
little  or  no  previous  experience.  All,  or  nearly  all,  the  variations 
which  furnish  material  for  Natural  Selection  are  fluctuations ;  that 
is,  they  are  small  plus  or  minus  variations  of  characters  previously 
existing,  and,  even  so,  not  of  the  whole  character  but  only  of  parts  or 
qualities  of  it.  By  their  accumulation  and  blending  during  ages, 
old  characters  are  lost  and  new  characters  created ;  or,  more 
commonly,  old  characters  are  so  modified  as  to  be  in  effect  new 
creations.  All  development  is  an  abbreviated  and  inaccurate  re- 
capitulation of  the  life-history  of  the  species.  Retrogression  plays 
as  important  a  part  in  evolution  as  progression.  Variations  are 
either  progressive  or  retrogressive.  Natural  Selection  has  so  dealt 
with  species  that  retrogressive  variations  tend  to  predominate 
somewhat  over  progressive  variations  because  they  tend  to  be  more 
numerous,  or  larger,  or  prepotent  in  the  blend,  or  on  all  these 
accounts.  As  a  consequence  all  characters  tend  to  retrogress  on 
cessation  of  selection.  Species  fit  their  environments  so  closely, 
and  their  physical  and  mental  parts  and  qualities  interlock  so 
exquisitely,  that  in  nature  mutations  can  rarely  be  adaptive. 
Owing  to  their  size,  and  to  the  alternative  mode  in  which  muta- 
tions tend  to  be  reproduced,  they  have  an  appearance,  but  only  an 
appearance,  of  great  stability.  When  reproduction  is  bi-parental 
and  the  species  is  sexually  dimorphic,  all  individuals  have  three 
sets  of  characters,  a  non-sexual  set  of  characters  all  of  which  are 
patent,  and  two  sets  of  sexual  characters  of  which  one  set  is  patent 
and  the  other  latent.  The  function  of  sex  is  to  blend  characters, 
and  the  ultimate  effect  of  blending,  combined  with  the  prepotency 
of  retrogressive  variations,  is  to  cause  the  retrogression  of  useless 
variations  and  characters  and  to  make  evolution  depend,  not  on 
the  persistence  of  the  variations  of  individuals,  but  on  the  per- 
sistence of  the  blended  variations  of  the  race  as  a  whole.  All  bi- 
parental  inheritance  is  blended,  the  apparent  non-blending  of  the 
sexual  and  Mendelian  characters  being  due  to  the  fact  that  the 
patent  set  from  the  one  parent  blends  with  the  latent  set  from 
the  other.  Natural  Selection  differs  from  Artificial  Selection 
in  that  the  former  is  founded  mainly  on  fluctuations,  whereas  the 
latter  is  founded  mainly  on  mutations.  Mendelian  reproduction  is 
an  anomaly  of  sexual  reproduction  whereby  non-sexual  characters 
are  reproduced  and  blended  in  the  same  mode  as  sexual  characters, 
one  of  each  allelomorphic  pair  being  patent  and  the  other  latent 


438    PHYSICAL  DETERIORATION  &  MICROBIC  DISEASE 

The  present  progressive  evolution  of  man,  at  any  rate  of 
civilized  man,  is  chiefly,  if  not  exclusively,  against  disease  which 
is,  apparently,  the  only  selective  agency  acting  on  him  sufficiently 
stringent  to  do  more  than  merely  maintain  characters  previously 
evolved.  Human  beings  differ  from  lower  animals  mainly  in  that 
they  owe  their  development,  especially  their  mental  development, 
to  a  much  greater  extent  to  the  stimulus  of  use  and  experience. 

718.  The  evidence  on  which  these  conclusions  are  based  is  very 
massive  and  appears  to  me  conclusive.     But  the  reader  is  now  in  a 
position  to  judge  for  himself.     Some  evidence  remains  for  con- 
sideration, but  it  can  be  dealt  with  conveniently  as  we  apply  our 
'laws1  to  the  practical  problems  of  human  life.     The  following 
are  the  factors  in  all  development:   (i)  capacity  for  growth  in 
directions  more  or  less  fixed  in  every  species,  but  so  differing  with 
different  species  that  the  latter  differ  in  their  characteristics ;  (2) 
stimulus  which  awakens  the  capacity;  and  (3)  nutriment  which 
supplies  the  material  for  all  growth  (as  well  as  the  stimulus  for 
much  of  it).     Capacity  for  growing  physically  and  mentally,  for 
responding  in  such  and  such  a  way,  in  such  and  such  a  degree,  to 
such  and  such  a  stimulus,  depends  on  the  antecedent  evolution  of 
the  race  and  the  variations  of  the  individual.     A  variation,  indeed, 
is  nothing  other  than  an  alteration  of  capacity  to  grow,  an  altera- 
tion which  is  founded  on  an  alteration  of  the  germ-plasm.    Capacity 
arises  in  the  race  through  slow  processes  of  selection  ;  and  can  be 
altered  in  it  only  through  selection  or  cessation  of  selection.     It  is 
that  with  which  every  individual  begins  life,  and  is  wholly  an  'inborn ' 
or  nutritional  character  which  cannot  be  increased  in  the  individual 
by  use  though  it  may  be  diminished  or  lost  in  him  through  injury.1 
It  must  be  borne  in  mind,  however,  that  the  effect  produced  by 
such  alteration  of  stimulus  is  limited  by  the  capacity  of  the  indi- 
vidual ;  thus,  no  matter  how  a  given  man  be  fed  or  trained,  he  cannot 
achieve  more  than  a  certain  degree  of  height,  strength,  or  capacity. 

719.  If,  then,  we  desire  to  improve  a  human  race,  two  ways  of 
attaining  our  aim  are  conceivable,     (i)    We  may  follow  the  plan 
of  Nature  and  of  plant  and  animal  breeders  and  alter  by  selection 
the  racial  CAPACITY  for  growth  in  this  or  that  direction  ;  or  (2),  by 
altering  the  conditions  under  which   the   individuals  of  the  race 

1  If  anything  may  be  rightly  described  as  innate  it  is  capacity.  In  a  sense  all 
capacities  for  growth  lie  latent  in  the  fertilized  ovum,  and,  with  variations,  are 
passed  on  to  the  descendent  germ-cells.  Thus  mathematical  knowledge  is  a  pure 
'  acquirement '  in  every  sense  of  the  term  ;  but  that  which  enables  it  to  arise  under 
the  stimulus  of  experience  has  its  roots  in  the  ovum. 


SELECTION  AND  TRAINING  439 

develop^  we  may  alter  the  kind  and  amount  of  STIMULUS  they 
receive.  Thus,  if  we  wish  to  increase  the  size  and  strength  of 
Englishmen,  we  must  breed  from  individuals  who  grow  big  and 
strong  under  present  conditions,  or  we  must  try  so  to  improve  the 
surroundings  that,  with  the  same  average  capacity  for  growth, 
individuals  will  grow  bigger  and  stronger  than  they  do  at  present. 

720.  Human  selective  breeding  presents  obvious  difficulties. 
It  is  possible  that  in  a  future  not  very  remote  some  control  will  be 
exercised  by  law  or  an  enlightened  public  opinion  over  the  multi- 
plication of  particularly  undesirable  types,  for  example,  imbeciles 
and  people  very  susceptible  to  tuberculosis  or  the  charm  of  alcohol. 
But  selection  with  a  view,  not  merely  to  prevent  marked  deteriora- 
tion, but  to  raise  the  general  standard  of  the  race  is  at  present  an 
impracticable  dream.  Moreover,  even  were  such  selection  practical 
it  would  have  to  be  undertaken  with  the  greatest  caution.  Mis- 
taken notions  as  to  what  characters  are  desirable  in  human  beings 
might  entail  disastrous  and  not  easily  remedied  consequences. 
That  mistakes  in  human  breeding  might  easily  be  made  is  evident 
from  the  fact  that  many  races,  including  our  own,  practise  mutila- 
tions as  a  means  of  improving  beauty,  and  that  the  majority  of  the 
people  of  all  races  greatly  admire  and  strive  to  perpetuate  a  very 
real  kind  of  stupidity.1  On  the  other  hand,  it  is  comparatively  easy 
both  to  alter  the  conditions  under  which  development  occurs,  and, 
even  in  the  very  next  generation,  to  remedy  altogether  any 
mistakes  that  might  be  made.  Clearly,  therefore,  it  is  better  to 
exhaust  the  possibilities  which  may  be  achieved  by  such  means  as 
improved  food,  housing,  and  physical  and  mental  training,  before 
we  attempt  to  tread  the  difficult  and  dangerous  path  of  selective 
breeding. 

721.  It  is  important,  therefore,  to  ascertain  as  precisely  as 
possible  what  characters  in  human  beings  it  is  practicable  to 
improve  by  altering  the  environment,  to  what  extent  they  may  be 
thus  improved,  and  by  what  means  the  improvement  may  be 
brought  about.  Only  so  shall  we  reach  that  bed-rock  of  fact  and 
clear  understanding  without  which  the  discussion  of  such  great 
problems  as  physical  and  mental  deterioration,  alcoholism,  public 
health,  social  and  moral  reform,  education,  and  the  like,  is  vague 
and  unprofitable.  I  am  not  aware  that  any  very  thorough-going 
endeavour  to  analyse  the  characters  of  living  beings,  especially 
human  beings — any  endeavour  to  separate  the  '  inborn  '  from  the 
'  acquired  ' — has  been  attempted  hitherto.  I  say  especially  human 

1  See  §§  805  et  seq. 


440    PHYSICAL  DETERIORATION  &  MICROBIC  DISEASE 

beings  because,  owing  to  more  intimate  knowledge,  we  are  better 
able  to  analyse  our  own  characters  than  those  of  other  types.  As 
far  as  I  am  able  to  judge,  the  apparently  fundamental  divergencies 
of  opinion  which  separate  various  classes  of  scientific  workers 
(biometricians,  Mendelians,  and  those  who  endeavour  to  take  other 
classes  of  facts  into  account),  social  reformers,  educationalists, 
and  the  like,  are  due  mainly  to  this  neglect.  Every  section 
appears  to  the  others  to  be  building  on  a  basis  of  unproved 
assumption.  A  common  platform  is  lacking.  In  attempting  the 
task  of  analysis  it  is  only  too  probable  that  like  most  other  pioneers 
I  shall  often  be  in  error.  Nevertheless,  however  wrong  I  may  be 
in  the  conclusions  I  reach,  yet  at  least  the  reader  will  be  placed  in 
possession  of  a  good  deal  of  material  evidence  which  he  will  be 
able  to  link  up  with  that  already  set  forth  in  this  volume,  and  apply 
to  the  problem  as  to  whether  it  is  possible  to  obtain  improvement 
in  this  or  that  character  (e.g.  intelligence)  by  altering  the  conditions 
under  which  individuals  develop,  or  whether  improvement  is 
possible  only  through  selective  breeding.  //  should  be  borne  in 
mind  constantly  that  selection  alters  only  capacity  for  develop- 
ment, whereas  improved  surroundings  alter  only  the  stimuli  which 
awaken  capacity.  Apart  from  selection,  then,  improved  human 
development  maybe  achieved  by  altering  the  supply  of  nutriment, 
by  removing  causes  of  injury,  and  by  altering  the  training  which 
the  body  and  mind  receive. 

722.  All  human  diets  contain  certain  necessary  constituents, 
water,  proteids,  carbohydrates,  various  salts,  and  the  like.  Almost 
all  diets,  whether  vegetable,  animal,  or  mixed,  contain  in  excess 
one  or  more  of  these  constituents,  and  a  deficiency  of  others.  If  in 
any  diet  the  quantity  of  a  necessary  constituent  is  deficient,  the 
instinct  of  the  individual  prompts  him  to  eat  till  the  deficiency  is 
supplied,  the  excess  of  the  other  constituents  being  wasted,  or 
within  limits  which  vary  with  the  individual,  stored  in  the  tissues.1 
For  this  reason  a  mixed  or  varied  diet  is  usually  the  most 
economical,  though  the  variations  of  the  individual  and  the  kind 
of  life  he  leads  must  be  taken  into  account.  We  tend  instinctively 
to  grow  tired  of  a  diet  which  contains  this  or  that  constituent  in 
excess,  and  to  turn  with  avidity  to  one  which  has  less  of  it,  but 
more  of  a  constituent  in  which  the  first  was  deficient.  Under 
1  This  power  of  storing  excess  of  nutriment  in  the  tissues,  especially  as  fat 
against  a  period  of  scarcity  is,  speaking  relatively,  of  little  use  to  the  average 
civilized  man  whose  supply  of  food  is  regular  and  secure  ;  but  it  must  have  been 
very  useful  to  his  remote  ancestors,  as  it  now  is  to  many  lower  animals — for  ex- 
ample, bears  during  hybernation  or  insects  when  undergoing  metamorphosis. 


NUTRIMENT  441 

special  conditions,  as  when  doing  hard  muscular  work  in  cold 
climates,  we  long  for  the  particular  constituents,  for  example,  fat 
and  sugar,  which  are  then  especially  needed.  Excess  of  this  or  that 
constituent  may  cause  injury  (e.g.  gout)  in  susceptible  individuals  ; 
individuals  may  vary  unfavourably  so  as  to  desire  excess ;  and 
often  individuals  develop  abnormal  and  injurious  tastes,  as  for 
alcohol  or  opium.  We  shall  consider  these  abnormal  desires 
separately  ;  but  meanwhile  it  may  be  stated  in  general  terms  that 
instinct  impels  the  individual  to  consume  about  the  right  quantity 
of  nutriment,  and  to  combine  the  right  constituents  in  about  the 
right  proportions. 

723.  Such  nutriment  as  the  normal  individual  receives,  pene- 
trates to  all  parts  of  his  body  and  nourishes  all  his  tissues.     It 
is  possible  to  control  the  quantity  taken  and  so  produce  the  general 
effects  of  extreme  starvation,  or  over-feeding,  or  anything  between  ; 
but  beyond  this,  our  power  is  very   limited.     For  example,  we 
cannot  by  special  forms  of  diet  increase  the  size  of  the  muscles 
as  compared  to  the  glands,  or  suppress  one  mental  trait  (e.g.  the 
sporting   instinct)   while   developing   another   (e.g.    mathematical 
talent).1     Apparently  when  nutriment  is  in  excess  no  tissue  uses 
an  excessive  quantity  of  food,  though  some  structures  eliminate 
the  excess,  and  others  store  it  for  the  future  needs  of  the  whole 
body.     When  the  supply  is  defective,  some  tissues  suffer  less  than 
others.     Thus,  inactive  structures  which  need  little  nutriment,  such 
as  bones,  or  very  important  structures  (e.g.  the  heart),  seem  then 
to  develop  better  than  more  active  or  less  vitally  important  parts 
such  as  the  voluntary  muscles.     Again,  wholly '  inborn  '  parts,  those 
for   which   nutriment   supplies   not    only   the   material,   but   the 
stimulus  for  growth,  appear  to  suffer  less  than  structures  which 
grow   under  the   stimulus   of  use.     Thus   the   hair,   teeth,   eyes, 
external  ears,  instincts,  memory,  and  the  like,  of  a  half-starved 
child,  seem  to  develop  better  than  its  limbs  or  its  mental  acquire- 
ments, and  the  structures  of  a  foetus,  all  or  nearly  all  of  which 
are   wholly    '  inborn/   appear  to    have   the    advantage    in    their 
competition  for  nutriment  with  the  physical  acquirements  of  an 
ill-nourished  mother. 

724.  Except  in  the  case  of  certain  unfortunate  sections  of  the 
community,   the  British   are   a   well    nourished  race.      Both  the 
quantity  and  the  quality  of  their  nutritive  supply  are  sufficiently 

1  Though  this  is  true  of  human  beings  it  is  not  true  of  all  animals.  Bees,  for 
example,  develop  into  workers  or  queens  accordingly  as  they  are  fed  on  one  kind 
of  food  or  another, 


442     PHYSICAL  DETERIORATION  &  MICROBIC  DISEASE 

good,  and  where  they  are  defective,  the  effects  and  the  remedy 
are  obvious.  It  follows,  since  human  diet,  consisting  as  it  does 
of  certain  essential  constituents,  cannot  be  greatly  varied,  since 
nutriment  penetrates  to  all  parts  of  the  individual,  since  the  supply 
of  nutriment  is  usually  sufficient,  and  since  instinct  prompts  to 
the  consumption  of  about  the  right  kind  and  quantity  of  nutriment, 
that  we  cannot  hope  to  improve  materially  such  a  people  as  the 
English  by  altering  its  nutritive  supply.  Especially  we  cannot 
hope  to  improve  its  inborn  traits — its  capacities  for  development, 
and  those  characters  which  arise  under  the  stimulus  of  nutriment. 
If,  therefore,  we  wish  to  alter  them,  the  only  conceivable  method 
is  selection.  Probably,  however,  no  one  would  wish  to  use  a 
method  so  difficult  to  manage  rightly,  so  destructive  of  liberty, 
so  fraught  with  suffering  to  the  innocent  as  selection,  merely  to 
change  the  shapes  and  sizes  of  such  physical  structures  as  ears, 
eyes,  lungs,  and  the  like,  and  no  one  who  understands  the  functions 
of  the  instincts  would  lightly  wish  to  tamper  with  these  exquisite 
mental  adaptations.  It  would  be  excellent,  of  course,  if  we 
exalted  the  potential  physical  and  mental  powers  of  Englishmen 
by  increasing  their  innate  capacity  to  develop  under  the  stimulus 
of  use  and  experience ;  but  it  is  so  much  easier,  so  much  more 
within  the  range  of  practical  politics,  to  alter  stimuli  by  changing 
the  conditions  of  life  than  to  alter  capacities  by  selection  that, 
before  attempting  the  latter,  we  should,  as  I  have  indicated  in 
general  terms,  be  very  sure  that  the  conditions  under  which  the 
British  dwell  are  such  as  ensure  the  utmost  development  and  the 
best  kind  of  development  possible.  Only  after  we  have  ascer- 
tained beyond  reasonable  doubt  that  nothing  more  is  achievable 
by  altering  the  conditions  can  selection  be  desirable. 

725.  The  different  parts  of  the  human  body  develop  under  the 
stimulus  of  use  on  lines  almost  as  rigidly  fixed  as  those  on  which 
they  develop  under  the  stimulus  of  nutriment.  Indeed,  the  physical 
growth  made  under  the  former  stimulus  is  usually  a  mere  exten- 
sion of  that  made  under  the  latter.  For  example,  a  human  limb 
develops  after  birth  on  lines  very  similar  to  those  on  which  it 
developed  before.  When  the  direction  or  character  of  the  growth 
is  changed  it  is  usually  by  injury,  not  by  use.  But  while  nutri- 
ment penetrates  to  all  parts  of  the  body  and  is  thus,  except  as  to 
the  quantity  consumed,  largely  beyond  control,  we  are  able  to 
regulate  in  great  measure  the  extent  to  which  the  different  parts 
of  our  bodies  are  used.  Thus  we  may  lead  a  hard  laborious  life 
as  that  of  a  navvy  or  hunter,  or  a  sedentary  one  as  that  of  a  clerk 


EXERCISE  443 

or  a  tailor ;  we  may  use  our  legs  much  or  little  as  compared  to 
our  arms ;  during  childhood  we  may  have  opportunities  of  indulg- 
ing in  many  active  games,  or  we  may  be  cramped  in  a  factory  or 
the  slums  of  a  great  city.  Though  the  diet  of  the  navvy  may  be 
less  appetizing  than  that  of  wealthier  people,  yet  it  is  usually 
sufficient  in  all  essentials  to  secure  full  physical  development. 
Not  so  the  work  of  the  clerk  or  the  tailor.  It  follows,  that  when 
individuals,  especially  individuals  belonging  to  different  sections 
of  the  community,  differ  in  those  characters  which  develop  under 
the  stimulus  of  use,  the  difference  is  less  certainly  founded  on 
germinal  differences  than  when  they  differ  in  the  characters  which 
arise  under  the  stimulus  of  nutriment,  for  example,  eye-colour. 

726.  Probably,  on  the  average,  some  sections  of  the  community, 
for  instance  the  men  of  the  leisured  classes  who  take  plenty  of 
exercise,  develop  under  the  stimulus  of  use  nearly  as  well  as  their 
capacities  permit.  It  is  quite  certain,  I  think,  that  other  sections, 
for  example,  clerks  and  slum-dwellers,  would,  under  other  condi- 
tions, develop  better  than  they  actually  do.  In  the  case  of  '  use- 
acquirements/  unlike  '  inborn '  traits,  it  is  evident,  then,  that  there 
is  scope  for  considerable  physical  improvement  in  certain  classes 
without  any  resort  to  selection.  But,  here  again,  the  means  of 
securing  improvements  are  so  obvious  as  to  be  non-controversial. 
Therefore  they  need  not  be  discussed  at  length.  The  debated 
point  is  the  extent  to  which  slum-dwellers,  for  instance,  owe  their 
physical  inferiority,  on  the  one  hand,  to  the  conditions  under 
which  the  individuals  are  reared,  and,  on  the  other,  to  germinal 
peculiarities  which,  as  is  alleged,  constitute  them  an  instrinsically 
degraded  race.  Speaking  generally,  biometricians  assume  that  the 
inferiority  is  germinal  and,  therefore,  beyond  cure  except  by  selec- 
tion. Medical  men  believe  it  is  partly  acquired,  partly  due  to  the 
inheritance  of  parental  acquirements,  and  partly  a  consequence  of 
the  direct  action  of  the  environment  on  the  germ-plasm  of  un- 
fortunate or  vicious  parents.  Believing  that  good  surroundings 
cause  intrinsic  racial  improvement  and  bad  conditions  degenera- 
tion, they  suppose  that  only  a  prolonged  revival  of  good  conditions 
will  remove  the  degeneracy.  To  me  it  seems  overwhelmingly 
probable  that  slum-dwellers,  factory  hands,  and  the  like,  are 
physically  inferior,  not  because  they  are  as  a  class  incapable  of 
developing  as  well  as  the  best  sections  of  the  community,  but 
mainly,  if  not  solely,  because  their  surroundings  are  such  that  they 
have  not  had  the  chance  of  developing  as  well  as  they  might.  I 
think  we  have  only  to  improve  their  surroundings  sufficiently  and 


444     PHYSICAL  DETERIORATION  &  MICROBIC  DISEASE 

the  deterioration  will  vanish  in  the  very  next  generation.  Judging, 
however,  by  the  evidence  given  before  various  Royal  Commissions 
by  multitudes  of  medical  men  and  others,  I  have  been  very  much 
alone  in  this  opinion  until  recently.  We  shall  deal  more  at  length 
with  the  question  immediately. 

727.  If  the  physical  use-acquirements  are  mere  extensions  of 
growth  made  under  the  stimulus  of  nutriment,  the  same  is  more 
rarely  true  of  mental  acquirements.     Sensations,  instincts,   and 
memory  (all  '  innate '  traits)  differ  sharply  from  the  contents  of  the 
memory  (all  '  acquired  '  characters.)     It  is  true  that  a  few  instinc- 
tive emotional  impulses  (e.g.   the  parental)  are  extended  by  ac- 
quirement.    It  is  true  also  that  we  acquire   through  experience 
emotional  impulses  to  action  and  c  physical '  dexterities  which  are 
close  imitations  of  true  instincts  and  instinctive  movements.     The 
latter  emotions  and  dexterities,  however,  are  not  usually  extensions 
of  previously  existing  characters.     For  example,  nothing  like  an 
inborn  love  of  a  particular  religion  or  of  dexterity  in  handling  a 
billiard  cue  is  inborn  in  the  individual.     These  and  their  like  are 
entirely  new  creations  due  to  experience  and  developed  in  the 
individual  in  lieu  of  any  one  or  more  of  a  thousand  alternative 
emotions  and  dexterities  equally  possible  of  attainment. 

728.  It  follows  that,  in  the  case  of  mind  more  than  in  the  case 
of  the   body,  there  is  scope  for  improvement  without  resort  to 
selection.     The  human  being  is  capable  of  developing  mentally  so 
greatly,  in  so  many  directions,  and  under  the  influence  of  so  many 
varieties  of  experience,  that  probably  no   man,   no  matter  how 
careful    his    training,    nor   what   ideals — moral,    social,    religious, 
intellectual,  practical,  and  so  forth — his  educators  had  in  mind, 
ever  received  a  perfect  mental  up-bringing,  ever  developed  mentally 
in  as  perfect  adaptation  to  his  total  environment  as  was  possible  to 
him.     In  the  absence  of  perfect  knowledge  and  wisdom,  the  choice 
of  his  guardians  has  always  fallen  short  of  perfection.     A  man  can- 
not be  taught  all  knowledge,  and  many  useful  or  admirable  mental 
habits  and  attitudes  are  incompatible  with  others.     Nevertheless, 
as  fitting  the  individual  for  his  environment,  the  mental  training 
of  most  men  somewhat  approaches  the  ideal.     And  this  is  more 
especially  the  case  in  savage  and  therefore  comparatively  simple 
states  of  society.     Sport,  imitativeness,  curiosity,  and  the  instinct 
to  play  with  the  contents  of  the  memory,  lay  the  foundations,  and 
the  child's  educators,  consciously  and  unconsciously,  strive  to  repro- 
duce  in   him   the  traits  which   enabled   them   to  survive  in  the 
common   environment.      Other   traits,   even   if  ideally  desirable, 


PHYSICAL  AND  MENTAL  TRAITS  445 

would  not,  speaking  generally,  be  useful.  Thus,  under  a  dominant 
church,  clear,  far-reaching,  fearless  love  of  truth  conduced  more 
often  to  death  by  torture  than  to  survival  during  the  dark  ages  of 
Europe.  Even  now  they  are  apt  to  handicap  the  individual  in 
many  walks  of  life ;  though  under  our  more  complex  and  en- 
lighted  conditions  a  greater  diversity  of  mental  type  is  both  possible 
and  beneficial  to  him. 

729.  From  the  point  of  view  of  the  social  reformer  the  impor- 
tant fact  is  that  man's  intellectual  powers,  including  his  capacity  to 
learn  even  in  old  age  and  to  communciate  his  acquired  knowledge, 
thoughts,  and  mental  attitudes  to  his  fellows,  confer  on  him  great 
powers  of  altering  the  mental  and  material  environment  and  of 
adapting  himself,  and  more  especially  the  next  generation,  to  the 
alteration.     Improved  mental  development  may  thus  be  made,  if 
not   positively  beneficial  to   the   individual   in  his    struggle    for 
existence,  at  least  not  positively  injurious.     For  example,  in  the 
course  of  one  or  more  generations  a  savage  environment  may  be 
exchanged  for  one  more  civilized  ;  or  an  atmosphere  of  prejudice 
and  superstition  may  be  made  to  yield  to   one   relatively  more 
enlightened.       Modern   Japan,   in  which   ideas  are   now   openly 
prevalent  the  expression  of  which  only  a  few  years  ago  would  have 
entailed  death,  is  a  case  in  point.     Though  the  mind  of  this  race 
has   altered   in  some   very   important   particulars,  though  it  has 
some   intellectual  characters  different  from  those  which  it  lately 
possessed,  yet  we  have  no  reason  to  suspect  any  germinal  altera- 
tion such  as  would  probably  be  indicated  by  a  marked  change  in 
physical  growth. 

730.  To    sum  up :   racial   capacities  for   physical   and   mental 
development  cannot  be  altered   except   by   selection,  or   lack  of 
selection,  or  in  rarer  instances  (as  in  the  case  of  European  breeds 
of  dogs  in  India)   through   injury  to  the  germ-plasm.     Speaking 
practically,  physical  and  mental  characters  which  develop  under 
the  stimulus  of  nutriment  cannot  be  improved  in  the  mass  of  the 
population  except  through  selection.     Physical  characters  which 
develop  under  the  stimulus  of  use  may  be  considerably  improved 
without  selection  in  many  sections  of  the  community ;  but  each 
improvement,    however     beneficial,    can    consist    only    in    mere 
extensions   of  growth   previously  made   under    the   stimulus    of 
nutriment.     On  the  other  hand,  it  is   probable  that  the  mental 
characters  which  develop  under  the  stimulus  of  experience  may  be 
immensely  improved  in   many   directions   in   all   sections  of  the 
community   by   careful   training  and  without  resort  to  selection. 


446     PHYSICAL  DETERIORATION  &  MICROBIC  DISEASE 

In  considering  any  practical  problem,  therefore,  we  must  first  of  all 
determine  what  we  propose  to  improve — whether  germinal  potentiali- 
ties, or  characters  which  developed  under  the  stimulus  of  nutrition,  or 
of  use,  or  of  injury — and  then  consider  in  what  way  they  may  best 
be  improved — whether  by  selection  or  by  altering  the  stimulus,  and 
if  the  latter,  how  the  stimulus  may  best  be  altered.  These,  then, 
are  the  general  considerations  we  must  bear  in  mind. 

731.  Physical  deterioration  in  slum-dwellers,  factory  hands,  and 
sedentary  workers  generally,  may  be  due  to  one  or  more  of  several 
conceivable  causes.     It  may  be  '  innate '  or  germinal,  in  which  case 
it  must  depend  on  antecedent  selection,  or  on  lack  of  it,  or  on 
injury  to  the  germ-plasm,  such  as  is  said  to  occur  in  European 
dogs  in  India  ;  or  it  may  be  due,  not  to   inferior  capacities  for 
development,  but  merely  to  inferior  growth  resulting  from  lack  of 
sufficient  food,  or  exercise,  or  from  injury  (e.g.  by  disease)  to  the 
growing  bodies,  the  soma,  of  the  young.     As  already  indicated, 
speaking  generally,  biometricians  and  medical  men  believe  that  the 
inferiority  is,  in  great  measure,  innate.     But  they  do  not  trace  the 
alleged  '  degeneracy '  to  the  same  source. 

732.  Biometricians  suppose  that  in  the  past  a  process  of  social 
sifting  has   separated   the   innately   superior    from   the   innately 
inferior    families    of   the   population,1  the   former   rising   to   the 
upper  and  middle  classes,  the  latter  becoming  the  dregs  that  settle 
in  the  slums  and  other  habitations  of  the  wretched.     But,  if  this  be 
true  of  the  town,  it  should  not  be  less  true  of  the  country.     Pre- 
sumably the  sifting  process  has  occurred  everywhere,  and  in  former 
centuries  as  well  as  at  the  present  time.     Our  towns  and  factories 
have  only  during  the  last  few  generations  absorbed  a  considerable 
proportion  of  the  population.     If,  then,4the  biometric  hypothesis  be 
correct,   agricultural   labourers   should   be    almost  as    physically 
inferior  to  members  of  the  upper  and  middle  classes   as  slum- 
dwellers  and  factory  hands.     But,  to  say  the  least,  of  this  there  is 
no  evidence.     Doubtless  some  of  the  inhabitants  of  the  slums,  as 
of  the  country,  are  people  who  have  sunk  through  the  germinal 
physical   inferiority  (i.e.  incapacity   to  develop  as   well  as   their 

1  May  I  remind  the  reader  that  the  words  '  innate '  and  '  acquired '  may  be 
used  in  two  senses,  one  of  which  is  correct  and  the  other  incorrect.  None  of  the 
characters  of  the  same  individual  are  more  innate  or  acquired  than  any  other. 
If  any  of  his  characters  are  innate,  then  all  are  innate.  If  any  are  acquired,  then 
all  are  acquired.  But  different  individuals  are  innately  alike  if  their  germ-plasms 
were  alike  ;  they  are  innately  different,  if  their  germ-plasms  were  different. 
They  are  alike,  or  unlike,  by  acquirement  if  stimuli  from  the  environment  have  so 
moulded  them  that  they  have  grown  alike,  or  unlike. 


SLUM  CONDITIONS  447 

fellows  under  similar  conditions  of  life)  of  themselves  and  their 
progenitors.  But  selection  is  keenest  where  the  struggle  for  life 
and  comfort  is  hardest — in  the  lowest  stratum  of  society.  Amongst 
the  very  poor  in  cities,  the  offspring  of  the  physically  and  mentally 
weak  are  often  of  necessity  more  exposed  to  neglect  and 
disease  than  the  children  of  their  stronger  fellows.  Moreover  they 
suffer  more  from  a  lack  of  good  and  sufficient  food.  Consequently 
in  slums,  far  more  than  in  the  country,  there  is  still  a  real,  though 
limited,  elimination  of  the  '  naturally '  weak  in  bone  and  muscle 
such  as  occurs  under  savage  conditions,  an  elimination  which  tends 
to  counterbalance  any  social  sifting.  The  sifting,  if  real,  is  further 
off-set  by  the  fact  that  the  town,  offering  better  wages  and  superior 
opportunities  for  enjoyment  and  openings  for  ambition,  attracts  the 
best,  the  most  robust  and  enterprising  of  the  peasant  stock.  But 
the  main  objection  to  the  biometric  hypothesis  lies  in  the  patent 
fact  that  in  the  modern  civilized  world  the  rise  and  fall  of  men  in 
the  social  scale  is  due  much  more  often  to  mental  than  to  physical 
peculiarities,  and  most  of  all  to  good  or  bad  fortune  occurring 
during  development.  In  the  slums  are,  doubtless,  some  people 
who  have  fallen  because  they  are  innately  somewhat  feeble- 
minded ;  that  is,  people  whose  mental  capacity  to  profit  by  ex- 
perience is  so  inferior  to  that  of  the  average  of  their  race  that  they 
have  sunk  in  consequence.  A  far  larger  number  have  sunk 
through  a  mental  susceptibility  to  the  charm  of  alcohol  which,  on 
the  average,  weighs  alike  on  them  and  on  their  descendants.  But 
probably  the  largest  number  have  descended,  not  through  any 
germinal  inferiority,  but  through  sheer  misfortune,  including  the 
great  misfortune  of  a  bad  mental  training.  Owing  to  the  growth 
of  machinery  and  population  there  is  not  enough  work  in  the 
land  for  all  the  hands  that  are  capable  of  doing  it.  Therefore  even 
some  of  the  capable  must  fail.  Once  a  family  has  fallen  into  the 
slums,  it  is  exceedingly  difficult  for  it  to  emerge  again — partly  owing 
to  the  lack  of  opportunity  which  extreme  poverty  entails,  and 
partly  because  the  physical  and  mental  traits  acquired  in  the  slum 
are  such  as  tend  to  unfit  the  individual  for  successful  life  in  any  other 
environment.  The  statistics  hitherto  compiled  by  biometricians 
demonstrate  the  precise  average  degree  of  physical  superiority  or 
inferiority  present  in  one  section  of  the  population  as  compared 
to  another.  But — if  the  thing  must  be  done  statistically — before 
we  can  decide  whether  the  difference  is  innate  or  acquired,  a 
further  inquiry  is  needed  in  which  the  children  derived  from  one 
section  are  compared  to  those  derived  from  another  after  all  the 


448     PHYSICAL  DETERIORATION  &  MICROBIC  DISEASE 

children  have  been  reared  under  identical  conditions.  This  inquiry 
might  be  made,  though  with  difficulty ;  for  in  the  slums  are  any 
number  of  people  immediately  derived  from  robust  English  and 
Irish  peasant  stocks,  and  these,  if  biometricians  are  right,  should 
be  physically  superior  to  the  rest  of  native  slum  population. 

733.  Medical  men  trace  physical  deterioration  to  the  direct 
effect  on  the  germ-plasm  of  such  agencies  as  insufficient  food,  bad 
hygiene,  disease,  and  alcoholism.  They  have  discovered  that 
apparently  no  British  families  of  a  purely  urban  descent  of  four 
generations  are  in  existence,  and  believe,  therefore,  that  the  germ- 
plasm  is  poisoned  so  rapidly  under  urban  conditions  that  the  town 
renews  itself  from  the  country  in  every  two  or  three  generations. 
But  the  very  magnitude  of  the  migration  into  the  town,  combined 
with  constant  intermarriages  between  the  urban  and  rural  popula- 
tions, renders  practically  impossible  a  purely  urban  descent  of  four 
generations.  The  absurdity  of  attributing  the  rarity  of  families  of 
pure  and  ancient  urban  descent  to  germinal  deterioration  is  seen 
very  clearly  when  we  consider  the  case  of  the  Jews.  These  people, 
who  intermarry  amongst  themselves,  are  often  desperately  poor, 
and  are  not  specially  clean  and  sanitary  in  their  habits  and 
dwellings.  Indeed  numbers  of  them  inhabit  the  worst  slums. 
Derived  by  an  almost  pure  descent  from  the  inhabitants  of  those 
terrible  slums,  the  ghettos  of  the  middle  ages,  and  rarely  inhabiting 
rural  parts,  they  are  the  most  extremely  urban  type  in  the  country, 
and  are,  nevertheless,  under  town  conditions,  the  most  hardy  and 
prolific  type  of  all.  Medical  writers  attribute  the  relative  immunity 
of  the  Jews  to  the  superior  care  bestowed  by  Jewish  women  on 
offspring.  But  while  Jewish  mothers  in  slums  are,  on  the  average, 
noticeably  more  healthy1  and  temperate,2  and,  therefore,  better 
able  to  rear  and  suckle  children  than  English  women  in  the  same 
surroundings,  neither  they  nor  their  children  are  appreciably 
cleaner,  nor  are  their  dwellings  better  than  those  of  the  natives. 
The  fact  appears  to  be,  then,  that  Jews  are  especially  healthy  and 
temperate  in  towns,  merely  because  they  are  derived  from  a  race 
which  has  been  fitted  by  prolonged  selection  to  urban  conditions. 
At  any  rate,  if  all  the  facts,  including  the  recent  evolution  of 
civilized  races,  are  taken  into  account,  I  can  think  of  no  other 
explanation  ;  and  none  other  has  been  suggested  except  that  the 
Deity  takes  particular  care  of  His  chosen  people,  or  that  the 
religious  training  of  the  Jews  results  in  better  maternal  acquire- 
ments than  Christian  training,  and  so  forth.  The  Chinese  appear 

1  See  §  435.  2  See  §  501. 


THE  CURE  OF  PHYSICAL  DETERIORATION        449 

to  be  quite  as  resistant  and  prolific  as  the  Jews,  and  it  will  hardly 
be  maintained  that  they  are  a  specially  favoured  or  well-trained 
race. 

734.  It  follows  that  urban  conditions,  except  perhaps  in  rare 
and  isolated  instances,  do  not  cause  deterioration  of  the  germ-plasm, 
but  merely  of  the  individual  exposed   to  them.     As  far  as  the 
evidence  indicates,  the  child  of  peasant  parents,  if  reared  in  the 
slums,   suffers  quite  as  much    as   the   offspring    of  a   town-bred 
family.       Indeed  the  survival  of  the  town  family  indicates  some 
degree  of  fitness  to  the  environment.     It  must  be  borne  in  mind 
that  the  physical  dangers  of  urban  life  arise  mainly  from  microbic 
disease,  which,  though  less  concentrated,  is  by  no  means  absent, 
even  in  the  most  sparsely  populated   localities  in   Britain.     The 
great  cities  of  the  present  day  have  grown  from  the  hamlets  and 
villages  of  the  past,  and  their  slow  increase  has  enabled  the  race  to 
adapt  itself  to  the  altered  conditions.     Even  now  our  villages  are 
training  the  race  for  existence  in  cities. 

735.  The    conclusion   we   reach,   then,   is    that    the   physical 
deterioration  which  accompanies  urban  life  may  be  removed  in  a 
single  generation  by  improving  the  conditions  of  life  under  which 
the  poor  dwell — by  providing  better  food,  housing,  sanitation,  and 
greater   opportunities    for    active   games   to   the   young.      Much, 
indeed,  has  been  done  already.     The  task  before  us  is  difficult, 
but  not  nearly  so  difficult  as  is  supposed  by   biometricians  and 
medical  men.     We  need  not  resort  to  selection,  unless  we  wish  to 
evolve  rapidly  a  race  capable  of  vigorous  life  in  slums.     It  would 
be  an  easier  and  quicker  proceeding  to  abolish  the  slums.     We 
need  not  wait  till  the  imaginary  innate  deterioration  caused   by 
generations    of  degradation  is  remedied  by  generations  spent  in 
better  surroundings.     Our  main  difficulties  arise  from  the  selfish- 
ness of  the  governing  classes,  the  intemperance  of  the  poor,  and  the 
ignorance  of  both.     If  all  classes  understood  the  causes  to  which 
physical  deterioration  is  due,  desired  its  removal,  and  were  willing 
to  work  and  spend  with  that  object  in  view ;  if  we  saw  to  it  that 
even  the  children  of  drunkards  had  proper  food,  care,  housing,  and 
exercise,  physical  deterioration  would  cease  to  characterize  sections 
of  the  people,  though  we  should  still  see  it,  as  amongst  the  upper 
classes  at  present,  in  individuals  who  were  congenitally  incapable 
of  attaining  average  physical  development. 

736.  Microbic  disease,  the  principal  source  of  physical  injury 
and    death   amongst   civilized   peoples,    affords   several   practical 
problems  of  great  interest  and  importance.     In  combating  it,  two 

29 


450     PHYSICAL  DETERIORATION  &  MICROBIC  DISEASE 

methods  of  procedure  are  conceivable:  (i)  we  may  attempt,  by 
what  may  be  termed  external  sanitation^  by  rendering  the 
environment  external  to  the  human  body  unfavourable  to  the 
microbes,  to  banish  the  organisms  that  cause  disease,  or  (2)  we 
may  strive  to  render  human  beings  more  resistant,  and  so  practise 
what  may  be  termed  internal  sanitation.  If  we  adopt  the  latter 
course  we  may  (A}  raise  the  innate  resisting  power  of  the  race  by 
altering  the  germ-plasm  by  artificial  selection,  or  (B)  that  of 
individuals  by  conferring  artificial  immunity  such  as  that  which  is 
acquired  to  smallpox  through  vaccination.  Artificial  selection, 
even  when  pressed  to  a  point  to  which  Natural  Selection  is  never 
pressed,  would  merely  increase  the  resisting  power  of  the  race.1 
That  is,  it  would  mitigate  the  severity  of  disease,  but  would  not 
banish  it.  On  the  other  hand,  acquired  immunity,  if  universally 
acquired,  would  banish  disease ;  for  the  micro-organisms,  deprived 
of  their  nutritive  supply,  would  become  extinct.  It  must  not  be 
forgotten,  however,  (a)  that  immunity  to  one  disease  does  not 
confer  immunity  to  any  other,  and  (b)  that  while  it  is  possible  to 
acquire  immunity  to  some  diseases  (e.g.  diphtheria  and  smallpox), 
it  is  not  possible  to  acquire  it  to  others  (e.g.  tuberculosis  and  leprosy). 
Therefore,  while  we  may  hope  to  banish  utterly  the  microbes  of 
such  a  disease  as  smallpox,  either  by  external  sanitation  or  by 
internal  sanitation,  we  can  hope  to  banish  the  microbes  of  such 
diseases  as  tuberculosis  only  by  external  sanitation.  It  is  true  that 
by  improving  the  surroundings  we  are  able  to  increase  the  power 
to  resist  tuberculosis  (and  its  consequences)  in  people  who  have 
lived  under  weakening  conditions  (e.g.  in  slums) ;  yet,  since  many 
people  living  under  the  best  conditions  take  the  disease,  it  is 
impossible,  merely  by  making  people  healthier  and  stronger, 
to  prevent  frequent  infection  and  therefore  propagation  of  the 
microbes. 

737.  Our  power  of  banishing  the  microbes  of  the  various 
diseases  by  external  sanitation  is  largely  conditioned  by  the  mode 
in  which  they  pass  from  one  human  being  to  another.  The 
contagious  diseases,  ophthalmia,  various  skin  complaints,  the 
venereal  maladies,  and  the  like,  are,  for  obvious  reasons,  particularly 

1  Selection  by  any  ill-condition  merely  increases  the  racial  power  of  resisting 
that  ill-condition.  It  cannot  procure  absolute  immunity  for  the  reason  that, 
when  the  severity  of  selection  is  relaxed,  retrogression  tends  to  follow.  Absolute 
racial  immunity  to  any  ill-condition  results  only  through  selection  by  agencies 
other  than  that  condition.  Thus  the  higher  animals  are  not  immune  to  the  assaults 
of  spiders  because  they  have  undergone  thorough  selection  by  spiders.  They  are 
immune  because  they  were  otherwise^selected. 


WATER  AND  INSECT-BORNE  DISEASES  451 

controllable.  Were  the  public  sufficiently  well-informed,  intelligent, 
and  careful,  they  should  disappear  within  a  very  few  years.  Even 
as  it  is,  with  the  exception  of  the  venereal  diseases,  cleanly  people 
rarely  suffer  from  them.  The  venereal  diseases  are  prevalent 
mainly  because  our  systems  of  religion  and  morality  are  still  so 
primitive  that  effective  sanitation,  like  personal  cleanliness  in  the 
early  ages  of  Christianity,  is  regarded  as  morally  reprehensible. 
Wilful  poisoning  with  arsenic  is  a  criminal  offence.  Wilful 
poisoning  with  syphilis,  even  of  an  innocent  wife  or  an  ignorant 
boy,  is  not  a  legal  crime. 

738.  The  water-borne,  the  *  filth  '  diseases,  enteric  fever,  cholera, 
dysentery,  epidemic  diarrhoea,  and   other   maladies  which  affect 
particularly  the  alimentary  canal,  are  also  very  controllable  by 
external  sanitation.     Except  under  special  conditions  they  do  not 
spread  rapidly,  and  their  mode  of  existence  outside  the  human 
body  is  such  that  they  are  extremely  open  to  attack.     Careful 
sanitation  has  almost  eliminated   them  from   many  areas  where 
they  were  formerly  prevalent.     There  is  no  apparent  reason  why, 
with  increasing  knowledge  and  efficiency  of  preventive  measures, 
they  should  not  be  banished  altogether.     As  in  the  case  of  the 
contagious  diseases,  artificial  selection  is  unnecessary,  and  artificial 
immunity  only  desirable  in   localities  where  sources  of  infection 
outside  the  human  body  are  yet  too  numerous  and  widespread  to 
be  controlled  by  the  system  of  sanitation  practised  or  practicable. 

739.  In   all   probability  insect-borne   maladies,  also,  will    be 
banished  in  no  very  distant  future  by  external  sanitation.     The 
destruction  of  the  intermediate  hosts  supplies  a  ready  means  of 
attack.     Already  Europeans,  owing  to  the  conditions  under  which 
they  dwell,  are  rarely  infected  by  plague  in  India,  even  when  it  is 
raging  amongst  the  natives.     Malaria  has  been  greatly  diminished 
in  many  parts  of  the  world  through  the  destruction  of  mosquitoes. 
The  same  means  have  been  effective  against  yellow  fever  in  Havana. 
Comparatively  little  as  yet  has  been  achieved  against  sleeping- 
sickness,  but  the  disease  has  not  long  been  studied,  and  the  life 
history  of  the  intermediate  host,  the  tsetse  fly,  is  not  fully  known. 
If  it  be  true  that  the  malady  is  conveyed  only  by  one  species  of 
insect  which  is  confined  to  the  shady  banks  of  streams,  it  may 
prove  possible  to  banish  it  more  easily  and  effectively  than  has  been 
found  possible  in  the  case  of  any  other  insect-borne  disease.     In  the 
case  of  insect-borne  diseases,  then,  selection  is  clearly  out  of  place. 

740.  As  far   as  we   are   able   to   judge    at  present,  air-borne 
diseases  will    never   be  banished    by  external  sanitation.     They 


452     PHYSICAL  DETERIORATION  &  MICROBIC  DISEASE 

pass  from  host  to  host  through  a  medium,  the  air,  which  is  essential 
to  human  existence,  and  which,  blowing  where  it  listeth,  cannot 
be  controlled  nor  efficiently  disinfected.  Speaking  practically, 
these  maladies  are  independent  of  climatic  or  other  local  conditions 
except  density  of  population.  Since  they  spread  with  a  rapidity 
which  is  proportionate  to  the  number  of  susceptible  individuals, 
and  since  immunity  to  them  is  conferred  by  illness  and  recovery, 
the  more  thoroughly  they  are  banished  from  a  community,  the 
greater  grows  the  number  of  susceptible  persons,  and  therefore  the 
liability  to  pestilence — to  disease  in  its  fearful  epidemic  form. 
In  England,  for  example,  only  the  endemic  prevalence  of  air-borne 
disease,  and  the  consequent  acquired  immunity  of  the  major 
portion  of  the  population,  preserves  us  from  disaster.  If  air-borne 
diseases  were  restricted  to  a  single  islet  for  a  generation,  the  rest 
of  the  globe  would  stand  in  danger  of  depopulation.  When  they 
broke  out  from  the  island  habitat  they  would  sweep,  as  in  ancient 
times,  over  the  whole  world — not  merely  in  one  great  and  terrible 
pandemic,  but  in  many  recurrent  and  devastating  epidemics,  each 
with  its  attendant  famine,  till  in  the  process  of  ages  the  epidemics, 
growing  more  frequent,  but  less  disastrous,  at  last  settled  again 
into  endemic  disease.  Therefore,  even  were  it  possible  to  banish 
measles,  and  whooping-cough,  for  example,  from  our  midst  by 
external  sanitation,  it  would  be  disastrous  to  do  so  while  they  yet 
lingered  in  any  quarter  of  the  globe,  and  it  would  always  be  hard 
to  ascertain  with  any  degree  of  certainty  that  some  such  spot  did 
not  exist.  In  civilized  countries  unavailing  attempts  are  con- 
stantly made  to  restrict  the  spread  of  measles  and  whooping-cough, 
as  by  closing  schools  during  such  slight  epidemics  as  occur 
amongst  us,  but  only  with  the  result  of  aggravating  future  epidemics. 
Isolation  is  quite  impracticable  except  when  the  great  majority  of 
the  members  of  the  community  have  already  been  infected  and 
thereby  have  acquired  immunity.1 

741.  Clearly,  then,  in  the  case  of  air-borne  diseases  we  have 
nothing  to  hope  from  external  sanitation.  From  artificial  selection, 
also,  little  or  nothing  could  be  gained.  Already  Natural  Selection 
is  very  stringent;  only  people  resistant  to  measles,  whooping- 
cough,  influenza,  and  probably  such  complaints  as  bronchitis, 
pneumonia,  and  rheumatic  fever,  survive.  Very  prolonged  and 
effective  artificial  selection  could  only  render  air-borne  maladies 
somewhat  milder  to  the  mass  of  the  population.  There  remains 
internal  sanitation — the  production  of  acquired  immunity  by  means 

1  See  §  454. 


AIR  AND  EARTH-BORNE  DISEASES  453 

of  vaccination  ;  that  is,  by  means  of  an  artificially  attenuated  form 
of  each  disease.  By  such  measures  smallpox,  the  most  dreaded  of 
all  air-borne  maladies,  has  been  almost  banished  from  various  parts 
of  the  civilized  world,  and  would  have  quite  disappeared  from  the 
globe  had  the  whole  human  species  for  the  term  of  a  generation 
been  vaccinated  at  intervals  of  a  few  years.  Thereafter,  the 
virulent  microbes,  having  become  extinct,  vaccination  itself  would 
have  become  unnecessary.  This  conclusion  may  appear  ex- 
travagant ;  but,  if  we  take  all  the  facts  into  account,  it  is  difficult 
to  escape  from  it.  In  Germany,  for  example,  smallpox  seems 
never  to  appear  except  as  an  importation  from  abroad.  What 
is  possible  in  one  country  is  possible  in  others. 

742.  Whether  internal  sanitation  can  be  made  as  effective  a 
weapon   against   air-borne   disease    in    general    as   it   is    against 
smallpox  in  particular  can  only  be  known  in  the  future.     As  yet 
we  have  made  no  more  than  a  beginning.      It  may  be  useful 
only  against  such  diseases  as  usually  confer  permanent  immunity, 
and  perhaps  it  will  ultimately  prove  impossible  to  attenuate  many 
air-borne  diseases  in  the  way  smallpox  has  been  modified — that 
is,  to  bring  about  such  an  attenuation  in  the  nature  of  the  microbes, 
that,  unable  to  exist  in  the  blood-stream,  they  are  confined  to  a 
single  locality  in  the  body,  and  so  are  incapable  of  reaching  the 
air   passages   and    infecting   the   atmosphere.      Antitoxins,  since 
they  induce  only  a  '  passive '  or  temporary  immunity,  cannot  serve 
the  same  purpose.     Moreover,  in  order  to  manufacture  antitoxins, 
it  is  necessary  to  keep  alive  the  virulent  microbes. 

743.  Immunity  to  leprosy  and  tuberculosis,  the  principal  earth- 
borne  diseases,  cannot  be  acquired  by  the  individual.     Therefore, 
internal    sanitation    supplies    no    weapon    against    them.       The 
infectivity  of  leprosy,  however,  is  very  low.     Owing  apparently  to 
the  isolation  of  sufferers,  and  the  increase  of  personal  cleanliness,  it 
has  been  banished  from  most  civilized  communities.     There  can 
be  little  doubt  that  ultimately  it  will  disappear  altogether.     On 
the  other  hand,  tuberculosis,  principally  a  disease  of  the  air  passages, 
is,  relatively,  highly  infectious.1      External  sanitation — improve- 

1 1  have  termed  tuberculosis  an  earth-borne  disease,  because  its  bacilli  rest 
when  outside  the  body  mainly  on  the  floor,  walls,  and  furniture  of  dwellings. 
But  since  they  are  inhaled  with  floating  dust  it  is  also  in  a  real  sense  an  air-borne 
malady.  To  me  the  evidence  that  it  enters  the  body  in  the  vast  majority  of  cases 
through  the  lungs  appears  overwhelming.  But  many  medical  men,  notably 
Behring,  favour  the  hypothesis  that  the  alimentary  canal  is  the  main  portal 
of  infection,  and  that  the  milk  of  tuberculous  cows  is  the  principal  vehicle.  It  is 
supposed  that  bacilli,  imbibed  during  infancy,  "  remain  latent  until  they  find 


454    PHYSICAL  DETERIORATION  &  MICROBIC  DISEASE 

ments  as  regards  light,  ventilation  and  air-space — has  somewhat 
reduced  its  prevalence,  and  may  continue  to  do  so  for  a  time.  But 
the  power  of  resisting  tuberculosis  is  a  direct  product  of  evolution. 
A  fall  in  the  mortality  due  to  it  implies  lessened  stringency  of 
selection,  which  in  turn,  if  carried  far  enough,  implies  retrogression. 
Therefore  to  procure  a  permanent  fall  in  the  death-rate,  it  is  not 

their  opportunity  [whatever  that  may  mean]  for  development,  and  that  individual 
predisposition  is  of  little  account."  But  how  in  that  case  is  it  possible  to  explain 
the  fact  that  consumption  tends  to  run  in  families  even  when  individuals  are 
separated  by  continents  and  generations  ?  It  can  hardly  be  that  the  members 
of  families  of  low  resisting  power  are  naturally  prone  to  use  tuberculous  milk. 
Besides,  the  very  people  who  suffer  most  from  tuberculosis  when  exposed  to  it  in 
infected  dwellings  are  precisely  those  who  have  had  no  opportunities  of  being 
infected  during  infancy;  who  have  never  drunk  any  milk  but  their  mother's 
milk ;  who,  indeed,  in  many  instances,  have  never  seen  a  cow,  let  alone  an  infected 
cow  ;  for  example,  Esquimaux,  Tierra  del  Fuegians,  Polynesians,  and  the  like. 
Deaths  from  the  various  forms  of  tuberculosis  occur  in  about  the  same  proportion 
in  Japan  as  in  Europe  ;  but,  according  to  Kitasoto,  tuberculosis  is  unknown 
amongst  the  Japanese  cattle,  infants  are  never  fed  on  other  than  human  milk, 
and  cow's  milk  is  so  little  used  that  the  daily  per  capita  consumption  by  the 
human  population  averages  no  more  than  three-quarters  of  a  teaspoon.  In  fact, 
cow's  milk  is  not  a  general  article  of  diet  in  Japan.  Additional  evidence  that 
tuberculosis  is  an  air-borne  disease  is  afforded  by  the  fact  that  a  sufferer  with 
phthisical  lungs  is  apparently  a  much  greater  danger  to  his  fellows  than  one  who 
suffers  from  tuberculosis  of  the  skin  (lupus).  It  is  possible  that  some  human 
beings,  especially  infants,  in  whom  the  alimentary  canal  is  the  principal  seat  of 
disease,  have  contracted  the  malady  from  tuberculous  milk  ;  but,  since  tubercle 
is  always  found  in  the  bronchial  glands  of  infected  children,  it  is  not  at  all  probable 
that  the  majority  of  sufferers  are  thus  infected.  More  especially,  it  is  improbable 
that  pulmonary  tuberculosis  occurring  in  adults  is  commonly  due  to  bacilli  imbibed 
in  milk  during  or  after  infancy.  The  Royal  Commissioners  "  Appointed  to  Inquire 
into  the  Relations  of  Human  and  Animal  Tuberculosis,"  after  conducting  a  long 
series  of  experiments,  maintain  that  human  and  bovine  tuberculosis  are  similar  in 
kind.  Since  tuberculosis  has  never  been  observed  in  wild  animals,  it  is  practically 
certain  that  the  bovine  disease  is  derived  from  human  sources.  Doubtless,  there- 
fore, they  are  right,  but  their  labour  was  unnecessary.  "  The  fact  that  the  bacillus 
of  bovine  tuberculosis  can  readily  by  feeding  as  well  as  by  subcutaneous  injection 
give  rise  to  generalized  tuberculosis  in  the  anthropoid  ape,  so  nearly  allied  to  man, 
and  indeed  seems,  so  far  as  our  few  experiments  go,  to  produce  this  result  more 
readily  than  in  the  bovine  body  itself,  has  an  importance  so  obvious  that  it  need 
not  be  dwelt  on  "  (Second  Interim  Report,  p.  14).  But  the  susceptibility  of  anthro- 
poid apes  only  proves,  as  might  have  been  expected,  that  their  bodies  furnish 
an  environment  favourable  to  bacilli  which  have  undergone  evolution  in  the 
allied  human  species.  But  apes,  unlike  Englishmen,  have  undergone  no  evolution 
against  tuberculosis.  They  are  in  the  position  of  Polynesians.  It  does  not 
follow  that  Englishmen  can  be  as  readily  infected  as  apes.  Judging  from  analogy, 
we  have  every  reason  to  believe  it  probable  (i)  that  bovine  tuberculosis  is  derived 
from  the  human  disease ;  (2)  that  the  microbes  of  it  are  becoming  adapted  to  the 
new  environment ;  (3)  that  they  are  becoming  less  adapted  to  the  old  environ- 
ment ;  and  (4)  that  consequently  they  are  less  virulent  to  human  beings  than  the 
microbes  derived  from  the  human  disease. 


TUBERCULOSIS  455 

enough  to  improve  the  sanitation ;  to  balance  the  increasing 
retrogression  continuous  improvement  is  necessary.  Doubtless,  if 
the  poor  Jews  of  the  slums,  who  as  a  class  are  probably  the  most 
resistant  in  the  community,  were  removed  to  better  surroundings, 
they  would  have  lower  death-rates  from  tuberculosis  than  before ; 
but  only  for  a  few  generations.  Gradually  the  rate  would  rise 
until  the  mortality  balanced  the  retrogression.  Even  among  our 
wealthier  classes  consumption  claims  its  toll  of  victims,  and  it  is 
difficult  to  believe  that  the  environment  in  cold  and  crowded 
England  can  ever  be  made  so  unfavourable  to  the  bacilli  as  it 
already  is  in  the  warm,  sun-bathed,  and  sparsely  populated 
Polynesian  Islands  where  the  native  races  are  undergoing  ex- 
termination. Isolation,  such  as  that  practised  in  sanatoria,  is, 
owing  to  the  vast  multitude  of  sufferers,  impracticable  as  a  general 
preventive  measure.  Speaking  practically  sanatoria  effect  cures 
only  amongst  highly  resistant  people  who  have  been  weakened  in 
worse  surroundings  A  great  number  of  those  who  improve  in 
them  return  to  perish  in  their  own  homes.  Consumption  is  never 
detected  in  its  earliest  stages.  The  victim  does  not  suspect  his 
disease  until  it  is  well  advanced.  Long  before  it  has  been  recog- 
nized, the  bacilli  have  been  disseminated  by  means  of  his  cough — 
not  only  in  large  masses  of  sputum,  but  in  a  fine  spray.  It  is  con- 
ceivable of  course  that  we  shall  one  day  discover  a  medicine  which 
will  act  as  effectively  in  tuberculosis  as  mercury  in  syphilis  and 
quinine  in  malaria ;  but,  since  tuberculosis  has  so  long  been  studied, 
this  is,  at  least,  improbable.  It  would  seem,  then,  that  the  only 
hope  of  permanently  reducing  the  mortality  from  tuberculosis  lies 
in  selection — probably,  in  the  first  instance  at  least,  not  a  selec- 
tion enforced  by  legal  penalties,  but  one  due  to  the  presence 
of  an  enlightened  public  opinion  which  will  regard  as  morally 
reprehensible  the  fertile  marriages  of  phthisical  types. 


CHAPTER    XXIV 

INTEMPERANCE  AND   INSANITY 

Immunity  to  alcohol — Evolution  and  retrogression — Attempts  to  suppress 
drinking  in  Mohammedan  countries — In  modern  civilized  states — In  the  United 
States,  Canada  and  Australasia — Failure  of  prohibition — Insanity — Two  distinct 
kinds — Lunacy — Feeble-mindedness — Definitions  of  idiotcy,  imbecility  and 
feeble-mindedness — The  Royal  Commission  on  the  Care  and  Control  of  the  Feeble- 
minded. 

744.  INTEMPERANCE.  Alcohol  is  capable  of  bestowing 
J^  keen  pleasure  on  many,  and  probably  some  pleasure  on 
all  people.  But  in  England  and  many  other  countries 
the  amount  of  pleasure  conferred  by  it  is  greatly  outbalanced  by 
the  suffering.  In  these  countries,  if  no  one  drank,  the  gain  would 
be  great,  though  not  so  great  as  if  all  men  drank,  as  most  men 
smoke  or  as  the  Jews  drink,  in  moderation.  Like  the  microbic 
poisons,  it  is  a  cause  of  disease  through  its  action  on  the  tissues  of 
the  body.  There  is,  however,  this  immensely  important  difference 
between  the  microbic  poisons  and  alcohol;  people  'take'  the 
former  in  spite  of  their  desires,  the  latter  because  of  their  desires. 
They  suffer  from  a  microbic  disease,  because  they  have  a  certain 
weakness  of  body  ;  from  intemperance,  because  they  have  a  certain 
peculiarity  of  mind.  It  follows  that  the  term  'immunity,'  when 
used  in  reference  to  microbic  disease  and  alcohol,  has  unlike 
meanings.  Used  in  reference  to  disease,  it  implies  that  the 
individual  is  physically  incapable  of  being  infected  under  the 
normal  conditions  of  life.  But,  though  a  given  quantity  of  alcohol 
is  less  poisonous  to  some  men  than  to  others,  no  man  is  physically 
incapable  of  swallowing  poisonous  doses  ;  and  many  men,  even  the 
most  resistant  physically,  take  it  in  such  doses.  Consequently, 
Nature,  taking  as  always  the  most  direct  course,  evolves  races 
which  are  mentally,  not  physically,  immune.  Immunity  to  alcohol 
implies,  therefore,  an  incapacity  to  be  tempted  by  the  narcotic  in 
harmful  quantities.  A  kind  of  immunity  to  alcohol  may  be 
created  by  fostering  a  moral  abhorrence  of  intemperance ;  but 
this  voluntary  avoidance  of  temptation  bears  no  likeness  to  what 
is  termed  immunity  to  disease — neither  to  the  inborn  immunity 

456 


IMMUNITY  TO  ALCOHOL  457 

which  prevents  infection,  nor  the  acquired  immunity  which  results 
from  infection  and  recovery.  It  resembles  more  closely  that  ex- 
ternal sanitation  by  means  of  which  we  endeavour  to  prevent  the 
infection  of  susceptible  people. 

745.  Susceptibility  to  the  charm  of  alcohol,  like  that  to  infection 
by  a  disease,  is  an  'innate'  character.     It  may  be  extended  or 
decreased  by  acquirement,  by  circumstances  affecting  the  mental 
state  of  the  individual  (e.g.  misery  or  happiness),  just  as  suscepti- 
bility  to   microbic   infection    may   be   altered    by   circumstances 
affecting  his  bodily  state.     But  it  may  be,  and  often  is,  present  in 
people  whose  circumstances  are  otherwise  of  the  happiest.     As  we 
have  seen,  it  is  much  more  pronounced  in  some  individuals  and 
races  than  in  others.     On  the  other  hand,  the  actual  craving  for 
alcohol  is  purely  an  acquirement,  a  mental  growth,  which  occurs 
only  in  susceptible  persons  who  have  had  previous  experience  of  the 
poison.     Within  limits,  which  vary  with  the  individual,  the  craving 
tends  to  increase  with  added  experience.     Herein  the  disease  of 
alcoholism  differs  sharply  from  such  a  malady  as  measles,  experience 
of  which  gives  origin  to  acquired  immunity.1    It  follows  that  internal 
sanitation,  the  procurement  of  immunity  through  experience  of  the 
poison,  is  impossible  in  the  case  of  alcohol.    Therefore,  if  we  wish  to 
benefit  the  race,  our  choice  of  action  is  limited  to  the  banishment  of 
alcohol  or  the  elimination  by  selection  of  the  susceptible  individual. 

746.  Alcohol,  a  waste  product  of  the  yeast  fungus,  is  derived 
from  sugar.     Speaking  practically,  both  sugar  and  yeast  are  pre- 
sent in  every  part  of  the  habitable  globe.    Their  area  of  distribution 
is  much  more  nearly  universal  than  that  of  any  disease.    Obviously, 
it  is  impossible  to  eliminate  either  the  one  or  the  other.     Alcoholic 
fermentation  occurs  constantly  in  nature,  but  human  art  is  neces- 
sary to  produce  the  narcotic  in  intoxicating  quantities.     The  art 
was  discovered  by  savages  at  some  period  enormously  remote  in 
human  history,  and  has  been  preserved  and  improved  ever  since. 
At  the  present  day,  in  addition  to  its  consumption  as  a  beverage, 
alcohol  is  useful  as  a  fuel,  a  solvent,  a  preservative,  and  the  like, 
in    many   of  our   industries.     Obviously   again,    it   is   practically 
impossible  to  suppress  the  manufacture  of  intoxicating  solutions. 
The  question  then  arises  whether  it  is  possible  by  legal  means  to 

1  It  will  be  noticed  that  I  compare  actual  alcoholism,  not  the  susceptibility 
to  it,  to  a  disease.  The  term  disease  is  often  applied  to  the  susceptibility.  It 
would  be  as  reasonable  to  describe  a  person  who  had  never  been  infected  by  measles 
as  suffering  from  that  malady.  Questions  of  nomenclature  are  not  trivial  when 
a  wrong  use  of  words  indicates  confusion  of  thought  in  the  speaker,  and  is  a  cause 
of  confusion  in  his  audience. 


458  INTEMPERANCE  AND  INSANITY 

suppress  its  use  as  a  beverage,  or  at  any  rate  its  immoderate  use. 
Probably  every  one  will  agree  that  purely  moderate  drinking  can- 
not be  enforced  by  law  in  a  race  many  members  of  which  are  capable 
of  enjoying  immoderate  drinking.  Human  nature  is  unable  to 
resist  the  strong,  steady  pull  of  a  constantly  nourished  temptation. 

747.  There  remains,  then,  the  total  suppression  of  alcohol  as 
a  beverage.     Suppose  for  a  moment  that  this  were  possible,  and 
that   a   law   enforcing    it   were    passed.       Then    a    race    like    the 
British^  which  had  undergone  some  evolution,  would  tend  to  retro- 
gress  towards   that  primitive   state   in   which    the   average    racial 
susceptibility  to  the  charm  of  alcohol  was  much  greater  than  it  is 
at  present.      Therefore,   if  at   any   future   period   this    law   were 
repealed    or    passed   into   abeyance,   the   last   state   of  the   race 
would  be  worse  than  the  first ;    for  the  race  began  its  evolution 
when  alcohol  was  hard  to  procure,  and,  in   any  case,  could  be 
obtained  only  in  very  dilute  solutions.     The  longer  the  law  was 
effectually  enforced   the  worse  would    be   the   ultimate   disaster. 
Our  literature,  both  ancient  and  modern,  is  full  of  references  to  the 
delights  of  drinking,  and  the  instinct  of  curiosity  is  strong  in  man. 
Any  one  who  could  read  and   possessed  fruit,  sugar,  or  starch, 
could  manufacture  alcohol  for  himself  in  secret.     Many  races,  the 
South  Europeans,  for  example,  derive  great  pleasure  and  little 
suffering  from  alcohol.     They  could  hardly  be  persuaded  to  pass 
a  self-denying  law  which  forbade  its  use,  and  which  benefited,  not 
themselves,  but  only  distant  races.     The  world  grows  increasingly 
cosmopolitan    every   day.      Merchants   and    travellers   conveying 
foreign    products   and   habits   pass   more   and    more   from   every 
quarter  of  the  globe  to  every  other.     As  surely  as  the  sun  shines, 
travellers  from  lands  where  the  use  of  alcohol  has  been  suppressed, 
would  learn  its  use  abroad,  and  seek,  in  the  end  successfully,  to 
reintroduce  it  to  their  own   countries.     Judging,  then,  from  the 
biological  standpoint,  external  sanitation  against  alcohol  cannot 
be    perpetually   successful.      Temporary    success    would    merely 
expose  the  race  to  dangers  similar  to  those  which  would  menace 
it  were  a  prevalent,  lethal,  and  highly  infectious  disease  banished 
from  the  country  but  not  from  the  world.     Since  alcohol  cannot 
be  banished  from  civilized  communities,  great  insusceptibility  to 
its  charm,  implying  evolution  and  therefore  selection,  is  essential 
to  the  existence  of  a  civilized  race. 

748.  However,    it    may   be    argued    that   "  Our    business    as 
practical  men  is  with  the  present,  and  not  with  a  remote  and 
problematical  future.     In  the  past,  men  have  rarely  sought  any- 


PROHIBITION  459 

thing  more  than  immediate  ends ;  yet  modern  civilization  has 
arisen.  Posterity  may  safely  be  left  to  redress  its  own  evils. 
Doubtless  it  will  discover  means  of  doing  so  at  present  unknown  to 
us."  Is  it  possible,  then,  in  the  immediate  future,  if  nothing  more, 
to  suppress  or  considerably  reduce  excessive  drinking  by  legal  or 
moral  methods  ?  An  immense  body  of  evidence  bearing  on  this 
problem  is  available.  All  history  indicates  that  as  soon  as  any 
race  gains  possession  of  considerable  quantities  of  alcohol,  that  is 
as  soon  as  it  reaches  the  earlier  stages  of  civilization,  it  begins 
attempts  at  temperance  reform.  Moderation  was  preached  at 
least  7000  years  ago  in  Egypt.  Prohibition  was  decreed  more 
than  a  thousand  years  before  the  Christian  era  in  China.  The 
ancient  Rechabites,  the  Gnostics,  the  followers  of  Montanism,  and 
the  Manicheans  were  professed  abstainers.  It  is  probable  that 
every  century  in  the  history  of  every  European  and  Asiatic 
community,  which  had  not  already  achieved  moderation  through 
selection,  has  been  marked  by  repeated  temperance  edicts,  some 
of  them  of  savage  severity.  The  final  result  is  that  the  use  of 
alcohol  is  now  less  controlled  and  more  nearly  universal  than  at 
any  former  period  of  the  world's  history. 

749.  Under  very  primitive  conditions  the  human  being  enjoys 
almost  as  much  freedom  as  a  wild  animal.     In  fact  he  is  a  wild 
animal.      As  society  organizes  itself,  and  the  individual  is  brought 
into  closer  and  more  constant  contact  with  masses  of  his  fellows, 
his  freedom  is  restricted  till  a  point  is  reached  when  the  nation  is 
regarded  as  the  property  of  some  person  who  is  believed  to  have, 
or  at  least  claims  and  enforces,  a  divine  right  to  deal  with  his 
subjects  as  he  pleases.     Later,  with  advancing  organization,  there 
is  a  return  towards  the  primitive  condition  of  individual  freedom. 
In    modern    England,   for   example,    the   individual   is   in    many 
respects  as  free  as  the  utter  savage.     The  general  tendency  of 
such  legal  restrictions   as   bind   him   is   merely  to   prevent   him 
curtailing  the  liberties  of  his  fellows,  or  breaking  such  engage- 
ments as  he  has  voluntarily  contracted. 

750.  Some  laws  which  are  possible  at  one  stage  of  civilization 
are  impossible  at  another.      If  incompatible  with  the  spirit,  the 
general  tendency  of  the  times,  they  quickly  pass  into  abeyance. 
Thus  during  the  Dark  Ages  of  Europe  edicts  for  the  maintenance 
of  uniformity  in  religion  were  often  terribly  effective.     They  would 
be  absurd   at  the  present  day.     A  year  or  two  ago  a  man  was 
forbidden  to  marry  his  deceased  wife's  sister  ;  it  is  probable  that  in 
the  future  he  will  be  permitted  to  marry  his  grandmother.     Laws 


460  INTEMPERANCE  AND  INSANITY 

prohibiting  drinking  are  just  such  interferences  with  individual 
liberty  as  cannot  be  enforced  in  modern  times.  It  will  be  observed 
that  I  do  not  maintain  that  such  laws  are  inherently  wrong.  I 
insist  merely  that  they  cannot  be  enforced.  It  will  be  observed 
also  that  I  speak  of  prohibition,  of  attempts  to  prevent  all  drinking, 
not  of  regulation,  of  attempts  to  place  the  consumption  of  alcohol 
under  such  conditions  that  moderation  is  encouraged,  so  that,  as 
at  an  ordinary  dinner  table,  the  drinker  does  not  interfere  with 
the  rights  and  comforts  of  his  fellows. 

751.  Under   semi-civilized    conditions   prohibitive   laws    have 
occasionally  met  with  temporary  success.     In  some  Mohammedan 
countries  they  have  had  prolonged  success.     Nevertheless,  intem- 
perance has  been  common  among  many,  and  especially  among  the 
more  enlightened  Moslem  communities.     Others  have  substituted 
opium  for  alcohol.     Religious  fanaticism  has  tended  to  keep  some 
Mohammedan    communities    both   sober   and    barbarous ;   but   it 
cannot  now  long  resist  the  influences  which  are  so  swiftly  chang- 
ing the  face  of  the  modern  world.     Presently  Nature  will  pass  the 
races  of  the  near  East  through  the  fire  which  has  hardened  their 
neighbours  against  the  stringent  conditions  of  civilized  life.     To- 
day, the  comparatively  drunken  Englishman  and  Russian  are  at 
a  disadvantage  in  the  struggle  for  life  and  wealth  as  compared 
to  the  temperate  Jew.     To-morrow  the  Mohammedans  will  face 
a  yet  heavier  handicap.     This  forecast  may  be  disputed,  but  we 
have   the   facts.      Has   a  highly  civilized  community  ever  existed 
which  had  not  already  passed  through  the  fire  ? 

752.  Prohibitory  laws,  when  enacted,  in  highly  civilized  states, 
have  almost  invariably  failed,  and  as  a  rule  worse  than  failed.     I 
say  '  almost,'  because  in  some  very  sparsely  settled  colonies  where 
temperance  sentiment  has  been  very  strong,  where  each  inhabitant 
is  known  to  all  his  neighbours  for  many  miles  round,  and  where 
the  channels  of  supply  and  communication  with  the  outer  world 
are  few  and  well  known,  prohibitory  legislation  appears  to  have 
achieved  a  temporary,  I  had  almost  said  a  momentary,  success. 
I  say,  '  worse  than  failed,'  because  in  places  where  the  population 
is  dense,  where  men  are  acquainted  with  few  even  of  their  near 
neighbours,  and  where  many  channels  of  supply  and  communica- 
tion exist  and  more  may  easily  be  organized,  attempts  at  repressive 
legislation  are  always  followed  by  increased   intemperance,  and 
by  even  greater  evils. 

753.  No    modern    civilized   government    has    attempted    the 
gigantic   task   of  abolishing   the   use   of  alcohol   throughout   its 


PROHIBITION  IN  AMERICA  461 

dominions.  But  various  areas,  possessing  local  self-government,  in 
he  English-speaking  settlements,  have  sought  to  enforce  abstinence 
>n  their  working-classes  by  prohibiting,  not  drinking  or  the 
mportation  of  alcohol,  but  only  the  manufacture  and  sale  of  it. 
'This  modified  form  of  prohibition  has  been  adopted  at  various 
times  by  seventeen  entire  States  of  the  American  Union.  "  It  is 
now  retained  only  by  three,  and  in  those  it  cannot  be  looked 
upon  as  a  success.  Parts  of  prohibitory  States  have  always  been 
in  open  rebellion  against  the  law ;  drinking  has  never  been  impos- 
sible ;  the  sale  of  liquor  has  always  been  profitable,  and  seldom 
disreputable  in  the  eyes  of  the  public.  Violation  of  the  law  has 
been  open  and  avowed.  Federal  law  requires  the  payment  of  a 
special  annual  tax  by  retail  liquor  dealers;  and  most  States, 
including  those  under  prohibition,  provide  that  the  payment  of 
the  tax  shall  be  prima  facie  evidence  of  a  sale  of  liquor  having 
been  made,  thus  utilizing  the  Federal  officials  in  the  detection  of 
illegal  traffic.  During  the  fiscal  year  ending  June  3<Dth,  1906,  the 
number  of  retailers  in  malt  liquors  were,  in  the  State  of  Kansas, 
4019  ;  in  Maine,  599  ;  and  in  North  Dakota,  1582 — these  being  the 
three  prohibition  States. 

754.  "In  urban  districts,  at  any  rate,  it  has  not  been  found 
possible  to  find  any  sound  ethical  basis  for  the  law,  or  to  persuade 
the  majority  to  regard  its  violation  as  immoral.    Without  the  backing 
of  public  opinion,  no  enforcement  of  prohibition  has  been  obtained 
except  at  the  price  of  raising  animosities  between  rival  factions 
of  such  intensity  as  seriously  to  disturb  the  community.     Juries 
have   violated    their   oaths ;    judges    have    hesitated    to    impose 
statutory  penalties  ;  blackmail  and  corruption  have  been  directly 
instigated,  and  the  law  in  general  has  been  brought  into  contempt. 
Persistent  disregard  of  the  liquor  laws  is  supposed  to  encourage 
disobedience  to  other  enactments,   and    an   example  is  cited   in 
Kansas,  where   the   fact   that  an  anti-gambling  law  is  almost  a 
dead    letter    has    been    attributed    to   the    lax    enforcement    of 
prohibition  in  the  cities  of  the  State. 

755.  "  It   should   be   mentioned    that   prohibition   prevents   a 
community  from  passing   any  laws  for  reclaiming  or  protecting 
its  drunkards.     Where  in  theory  there  is  no  drinking,  in  theory 
there  can  be  no  intoxication  ;  but  from  the  practical  point  of  view 
such  arguments  cannot  be  justified."  l 

1  Report  on  the  Liquor  Traffic  Legislation  of  the  United  States,  prepared  by  Mr 
R.  C.  Lindsay,  Second  Secretary  to  His  Majesty's  Embassy  at  Washington,  and 
issued  by  the  Foreign  Office  in  April  1907. 


462  INTEMPERANCE  AND  INSANITY 

756.  The  difficulty  of  enforcing  prohibition  under  the  ordinary 
conditions  of  civilized  life  is  shown  by  the  fact  that  only  very 
thinly  populated  states  of  the  American   Union  have  continued 
the   attempt.     In    1890,  North   Dakota  had  four  persons  to  the 
square   mile,    Kansas   seventeen,    and    Maine   twenty.      None    of 
these    States    had    a    town    of    50,000    inhabitants.       Speaking 
practically,  in  no  town,  not  even  in  what  we  in  England  should 
term   a  village,  was  there  more  than  a  pretence  of  prohibition. 
At  that  date  the  States  that  have   abandoned  prohibition    had 
on  the  average  a  population  four  or  five  times  denser  than  the 
population  of  those  that  have  retained  prohibition.     Nineteen  per 
cent,  of  the  inhabitants  of  the  former  dwelt  in  towns  of  more  than 
50,000  inhabitants.     The  difference  has  since  increased.     West- 
moreland, the  most  sparsely  populated  English   county,  had,   in 
round   numbers,  in   1891,  a  population  of  eighty  persons  to  the 
square  mile,  Lancashire   and    Surrey   had    2000,  and   Middlesex 
n^oo.1 

757.  Prohibition   applied  to   more   limited   areas   than  entire 
States  is  termed  local  option.     Owing   to  the  greater  ease  with 
which   alcohol  may  be   obtained  from    neighbouring  areas   it   is 
correspondingly  easy  to  enforce  as  regards  the  manufacture  and 
sale  of  drink,  but  is  even  less  effective  as  regards  the  consumption 
of  drink.     It  has  been  enacted  in  many  States  of  the  American 
Union,  in  Canada,  and  in  Australasia.     Like  *  total  prohibition/  it 
is  possible  that  it  has  achieved  partial  and  temporary  success  in 
some  very  wild  and  sparsely  inhabited  districts  such  as  parts  of 
Dakota.     It  is  certain  that  it  is  a  complete  failure  in  every  town 
and  densely  inhabited  rural  district.2 

758.  Mere  failure  would  leave  matters  no  worse  than  before; 
but   here    failure    is    accompanied    by   many   evils.      For    open 
drinking  under  the  eyes  of  the  public  and  police,  whose  business 
it   is   to   prevent   excessive    drinking,   is   substituted   secret   and 
uncontrolled  debauchery.      The  actual  amount  of  intemperance 
is  increased ;  men  make  sure  of  drinking  their  fill  while  they  have 
the  opportunity ;  they  drink  in  surroundings  where  the  greatest 
possible  amount  of  harm  results,  and  are  given  every  facility  for 
excessive   indulgence.      Drug   stores,   normally   conducted    by   a 
very   respectable  class   of  men,   become   drink-shops  which   sell 
in   addition   immense   quantities   of  such   narcotics   as   morphia, 

1  For  evidence  concerning  the  statements  in  this  paragraph  see  The  Temperance 
Problem,  by  Messrs  Rowntree  &  Sherwell,  pp.  115-249. 

2  Op.  cit.,  pp.  250-369. 


PROHIBITION  IN  AMERICA  463 

laudanum  and  cocaine.1  The  police  turn  aside  from  an  impossible 
task.  Successful  evasion  of  one  important  law  tends  to  produce 
contempt  for  all  law.  Widespread  demoralization  follows.  Crying 
evils  exist  unredressed  ;  politics  become  merely  a  struggle  between 
prohibitionists  and  their  opponents.  Politicians,  seeking  place, 
support  one  side  or  the  other  regardless  of  their  private  opinions 
and  practices.  These  statements  are  very  sweeping,  but  they  are 
supported  by  any  amount  of  evidence.2 

759.  Other  things  equal,  large  towns  tend  to  be  more  in- 
temperate than  smaller  towns,  and  floating  populations  than  fixed 
populations.  In  1898,  the  latest  year  for  which  statistics  are 
available,  the  inhabitants  of  New  York  numbered  3,500,000,  of 
Chicago  1,850,000,  of  Boston  582,463,  and  of  Portland,  the  capital 
of  Maine  and  the  classic  prohibition  city,  41,508.  Eighty  per  cent, 
of  the  population  of  Portland  were  native-born.  The  convictions 
for  drunkenness  per  1000  inhabitants  were  in  New  York  13,  in 
Chicago  23,  in  Boston  45,  in  Portland  42.  New  York,  Chicago 
and  Boston  permit  the  sale  of  drink  ;  but  Boston  is  a  *  safety-valve ' 
in  the  midst  of  a  prohibition  area  from  which  came  44  per  cent,  of 
the  inebriates  convicted  in  its  courts.  Nor  was  drunkenness  con- 
fined to  it.  Cambridge,  one  of  its  suburbs,  is  the  largest  prohibi- 
tion city  in  the  States  ;  since  it  adopted  '  no  license  '  it  has  doubled 
its  own  convictions  per  thousand  of  population.  When  prohibition 
was  first  introduced  into  Portland,  the  convictions  for  drunkenness 
averaged  16  per  looo.3  General  Neal  Dow,  to  whom  more  than  to 
any  other  one  man  its  establishment  was  due,  stated  in  his  evidence 

1  "  On  August  3ist,  1899 — a  week  prior  to  our  visit — another  '  raid  '  was  made 
on  a  few  of  the  saloons  (including  one  bottling  factory),  and  more  than  a  thousand 
gallons  of  beer,  wine  and  spirits,  were  seized,  of  which  nearly  one-half  (47  5  £ 
gallons)  was  seized  at  one  establishment — a  so-called  '  drug-store  '  with  a  large 
bar  in  the  rear  of  the  shop.  This  raid,  however,  like  its  predecessors,  had  to  be 
made  over  the  heads  of  the  city  and  county  officials  "  (The  Temperance  Problem, 
p.  195).  "  In  the  regular  drug-stores,  and  in  160  of  the  172  general  stores  in  the 
State  of  Vermont  (then  under  prohibition),  they  sell  every  month  3,300,000  doses 
of  opium,  besides  what  they  dispense  in  patent  medicines,  and  besides  what  the 
doctors  dispense  (90  per.  cent  of  the  doctors  dispense  their  own  medicines),  which 
gives  one  and  a  half  doses  of  opium  to  every  man  and  woman  in  the  State  of 
Vermont  above  the  age  of  twenty-one  years  every  day  in  the  year.  (By  dose  I 
mean  i  grain  of  opium,  %  of  a  grain  of  morphia,  %  ounce  of  paragoric,  and  20  drops 
of  laudanum).  And  the  amount  consumed  would  average  a  dose  to  every  man, 
woman,  and  child  in  the  State  of  Vermont  every  day  in  the  year"  (Dr  Ashbel 
P.  Grinnell). 

z  Readers  desiring  fuller  evidence  than  I  have  space  for  will  find  it  set  forth  in, 
amongst  other  works,  The  Temperance  Problem,  and  the  Reports  of  the  A  merican 
Committee  of  Fifty  to  Investigate  the  Liquor  Problem. 

3  The  Temperance  Problem,  p.  701. 


464  INTEMPERANCE  AND  INSANITY 

before  the  Royal  Canadian  Commission,  "  When  I  was  Mayor 
(1851)  every  man  who  indicated  he  was  drunk  was  arrested,  but 
now  they  do  not  do  that  unless  the  man  is  noisy  and  disturbing 
the  peace."  Another  witness,  a  "  Past  Most  Worthy  Patriarch  of 
the  Sons  of  Temperance,"  on  being  told  that  evidence  had  been 
given  that  men  drunk  but  not  disorderly  were  not  arrested,  and 
that  in  the  preceding  year  "  men  shook  their  fists  in  the  face  of  the 
Police  in  Portland,  and  dared  them  to  arrest  them,"  said,  "  I  have 
no  doubt  of  it."  "  And  that  would  naturally  reduce  the  number 
of  arrests  very  largely  in  the  city  of  Portland  ?  "  "  Yes." l  The 
following  sums  up  the  case  very  fairly  :  "  Every  word  of  Mr  Morris' 
(Rev.  Phillip  H.)  arraignments  of  the  prohibitory  law  is  true.  He 
might  have  made  it  much  stronger  and  still  kept  within  the  borders 
of  truth  ....  Prohibition  has  remained  upon  the  Maine  statute 
books  for  half  a  century,  for  the  single  reason  that  it  has  never 
been  enforced.  One  year  of  genuine  enforcement,  and  it  would  be 
abolished  as  soon  as  the  legislature  could  be  got  together  .  .  . 
'  Make  the  law  respected  where  it  is  a  law/  said  Mr  Moore.  There 
is  the  solution.  Make  the  law  respected,  and  everybody  except 
the  theorists  who  now  sustain  it  will  demand  its  repeal."  2 

760.  The  evidence  concerning  the  failure  of  prohibition  and 
local  option  in  other  parts  of  the  United  States,  in  Canada,  and  in 
Australasia  is  similar  in  kind  and  quite  as  conclusive.  Of  Canada, 
the  Report  (1895)  of  the  Royal  Commission  says,  "  in  short  the  law 
as  an  aggressive  weapon  has  been  abandoned."  In  Australia  one 
1  town,'  the  Moonta  mines  township,  is  said  to  be  under  '  prohibi- 
tion.' Another,  Mildura,  has  closed  its  public  houses,  but  alcohol 
is  sold  in  clubs.  "  There  is  no  haughty  exclusiveness  about  these 
clubs.  The  members  appear  to  be  anxious  to  extend  the  right 
hand  of  good  fellowship  to  all  comers,  so  that  no  man  need  go 
athirst."  3  New  Zealand  has  a  law  of  local  option.  At  the  election 
of  1905  *  no  license '  was  adopted  by  six  out  of  sixty-five  districts. 
It  has  been  in  operation  longest  in  the  Clutha  district,  and  the 
King  country,  the  inhabitants  of  which  are  aborigines.  Its  success 
may  be  gauged  by  the  following :  "  The  Maori  chiefs  in  the  King 
country,  New  Zealand,  have  asked  the  Government  to  substitute  a 
limited  licensing  system  for  the  prohibition  which  is  in  force  at 

1  Quoted  by  Rowntree  &  Sherwell,  op.  cit.,  p.i6o. 

2  Biddeford  (Maine)  Daily  Record,  April  24th,  1899,  quoted  by  Rowntree  & 
Sherwell,  op.  cit.,  p.  198. 

3  The  Report  to  the  Victorian  Board  of  Public  Health,  by  Dr  Robertson,  quoted 
by  Edwin  H.  Pratt.     The  Licensed  Trade,  p.  141  (London,  Murray). 


THE  KINDS  OF  INSANITY  465 

present,  and  under  which  liquor  of  bad  quality  is  being  sold  every- 
where. Mr  Seddon,  the  Premier,  approves  of  the  proposal.  He 
told  a  deputation  that  the  chiefs  and  the  police  were  unanimous  in 
stating  that  prohibition  had  spread  the  evil  it  had  been  intended 
to  exclude.  Sly  grog-selling  is  rampant  and  could  not  be  stopped. 
The  same  thing  was  going  on  in  the  Clutha  district  in  Otago,  where 
there  were  no  Maoris,  and  where  prohibition  was  enforced  by 
popular  vote."  1 

761.  A  law  forbidding    the    use    of  alcohol  is  as  much   an 
anachronism  as  one  enforcing  a  belief  in  the  Thirty-nine  Articles, 
or  the  Darwinian  Doctrine  of  Descent.    Prohibition  merely  deprives 
the  authorities  of  much  of  their  power  of  controlling  intemperance 
and  tends  to  make  them  partners,  pensioners,  or  blackmailers  of 
law  breakers.     The  whole  habit  of  modern  thought  and  behaviour, 
the  whole  fabric  of  civilized  society  is  against  its  effective  adminis- 
tration.    But  that  which  cannot  be  altogether  prevented  may  to 
some  extent  be  regulated  and  diminished.     Up  to  a  certain  point 
it  is  possible  to  control  the  drink  traffic ;  attempts  to  pass  that 
point  usually  end  in  worse  than  failure.     Drinking  there  is  sure  to 
be,  but  the  more  openly  it  is  conducted  the  less  imperfect  are  the 
facilities  for  control.     If,  were  it  possible,  all  public  houses  and 
clubs  had  glass  walls,  intemperance  would  be  reduced  to  a  mini- 
mum.    Very  little  drunkenness  occurs  in  the  cafes  of  the  French 
Boulevards.     If,  then,  we  wish  to  benefit  the  race  in  the  immediate 
future  our  endeavour  should  be,  not  to  prevent  drinking,  for  that 
is  impossible,  but  to  bring  all  places  where  excessive  drinking  is 
likely  to  occur  more  thoroughly  under  the  hand  of  the  public 
authorities.     That  is  the  only  method  of  external  sanitation  with 
respect  to  alcohol  which,  in  civilised  communities,  has  been  at  all 
successful  in  the  past  or  is  likely  to  be  successful  in  the  future. 

762.  Insanity.     Two  very  distinct  kinds  of  insanity  are  observ- 
able : — (A)  The  individual  may  possess,  and  usually  does  possess 
in  average   degree,    every   mental    faculty    found    in   the   normal 
human  being  except  one — memory.     Thus  he  may  have  all  the 
human   instincts,   imitativeness,  curiosity,  sexual  inclination,  and 
the  rest ;  but  he  is  more  or  less  incapable  of  storing  experience — 
incapable  of  filling  his  conscious  memory  with  data  which  may 
be    recollected,   and    his    unconscious    memory   with    '  acquired ' 
dexterities  and  habits.     If  his  lack  of  memory  is  very  great,  he 
is  an  idiot,  unable  perhaps  to  learn  to  walk  or  speak.     A  lesser 
degree    of  incapacity   to    learn    constitutes   imbecility.       A    still 

1  The  Morning  Post,  Oct.  29th,  1900. 
3° 


466  INTEMPERANCE  AND  INSANITY 

lesser  degree,  feeble  -  mindedness.  There  is,  however,  no  sharp 
line  of  demarcation :  imbecility  and  idiocy  are  merely  graver 
phases  of  feeble-mindedness.  The  defect  of  memory  is  usually 
general :  but  in  some  cases  it  is  more  or  less  limited  to  particular 
departments  of  mental  acquirement.  Thus  there  are  *  moral 
imbeciles '  who,  while  able  to  make  other  mental  acquirements, 
are  unable  to  acquire,  in  the  form  of  imitation  instincts,  the  code 
of  morals  prevalent  in  the  community  in  which  they  are  reared. 
The  low  tone  of  morality,  especially  sexual  morality,  so  common 
amongst  the  feeble-minded,  however,  is  more  often  due  to  general 
incapacity:  the  individual  possesses  normal  instincts  which,  like 
other  animals,  he  tends  to  obey,  but  which  he  does  not  learn  to  con- 
trol like  the  average  human  being.  To  lack  of  memory,  also,  is 
attributable  his  deficiency  in  the  'higher  faculties,'  for  example 
intelligence  and  reason.  Probably,  in  comparison  to  the  rest  of 
our  powers,  we  are  all  feeble-minded  to  some  extent  in  one  or  more 
particulars.  Thus,  while  possessing  fair  capacity  in  most  depart- 
ments of  mental  acquirement,  we  may  be  relatively  incapable 
of  accumulating  musical,  lingual,  or  mathematical  efficiency.  The 
connection  between  weak-mindedness  and  incapacity  to  learn  is 
clearly  seen  when  we  consider  that  if  we  lacked,  as  some  people 
do,  such  an  instinct  as  the  sexual  or  the  parental,  the  function 
of  which  is  not  to  impel  us  to  make  acquirements  useful  to 
our  selves  >  we  should  not  necessarily  seem  feeble-minded.  But 
lack  of  imitativeness  or  curiosity  would  almost  necessarily 
lead  to  a  condition  of  mental  dullness  closely  resembling 
imbecility. 

763.  (B)  The  individual  may  be  a  '  lunatic,'  quite  normally 
capable  of  recollecting  experiences  and  learning  dexterities  and 
habits.  But  the  universe  his  mind  constructs  for  him  differs 
markedly  from  that  created  by  the  minds  of  normal  people.  He 
feels  and  thinks  abnormally.  His  experiences  impress  his  mind 
in  an  unusual  way,  and  he  draws  unusual  inferences  from  them. 
He  has  hallucinations  and  delusions.  What  to  the  normal  person 
is  a  shadow  on  the  wall,  may  seem  to  him  the  devil.  Common 
sounds  may  have  an  awful  significance, 

"  As  the  Lord  were  walking  near, 
Whispering  terrible  things  and  dear." 

The  sight  of  two  people,  perhaps  strangers,  in  conversation  may 
create  a  conviction  that  they  are  plotting  great  good  or  harm  to  him. 
The  ordinary  behaviour  of  his  fellows  may  give  rise  to  the  notion 


IMBECILITY  AND  LUNACY  467 

that  they  are  persecuting  him,  or  on  the  other  hand,  to  a  belief 
that  they  admit  his  claim  to  be  monarch  or  deity. 

764.  Obviously,  then,  the  difference  between  the  two  kinds  of 
insanity  is  very  great.     Idiocy  is  a  condition  in   which  there  is 
little  or  no  capacity  to  learn  ;  lunacy  a  condition  in  which  there 
is  capacity  to  learn  but  in  which  there  is  much  wrong  learning. 
Both  kinds  of  insanity  can  be  imitated  in  greater  or  lesser  degree 
by  people  who  are  quite  capable  of  normal  development.     Thus 
training  may  so  close  a  man's  mind  as  to  render  him  more  or 
less  unable  to  profit  by  experience,  or  it  may  endow  him  with 
strange  and  what  seem  to  non-believers  absurd  delusions,  as  in 
the  case  of  the  adherents  of  many  religions.     Feeble-mindedness 
may  arise  from  injury  to  the  brain  at  any  period  of  life,  and  it 
is  not  an  unusual  accompaniment  of  extreme  old  age  ;  but  it  is 
seen  typically  most  commonly  in  people  who  from  birth  forwards 
are  more  or  less  incapable  of  making  mental  acquirements.     On 
the  other  hand,  lunacy,  at  any  rate  clearly  marked  lunacy,  almost 
invariably  manifests  itself  during  or  after  adolescence. 

765.  Probably  most  alienists  will   accept   my   description   of 
lunacy  as  correct.     There  is  nothing  new  in  it  except  perhaps  the 
stress  laid  on  memory  in  the  statement  that  this  form  of  mental 
defect  is  due  to  wrong  learning.     But  the  description  of  feeble- 
mindedness is  new.     If  it  be  correct,  then,  the  importance  of  the 
part  played  by  memory  in  human  mental  development  has  been 
as  insufficiently  realized  by  alienists  as   by  students  of  normal 
psychology.    However,  when  we  study  their  descriptions  of  the  con- 
dition, we  find  that  simple  incapacity  to  learn  is  always  implied, 
though,  owing  to  non-recognition  of  the  fundamental  truth,  other 
mental  states  which,  on  consideration,  would  be  admitted  as  not 
especially  those  of  imbecility,  are  sometimes  included.     Consider, 
for   example,  the    following   description   supplied  by  the  Royal 
College  of  Physicians  to  the  Royal  Commission  on  the  Care  and 
Control  of  the  Feeble-minded. 

766.  "  *  Idiots,'  i.e.   persons  so  deeply  defective  in  mind  from 
birth  or  from  an  early  age  that  they  are  unable  to  guard  them- 
selves from   common    physical  dangers,  such  as,   in   the  case  of 
young  children,  would  prevent  their  parents  leaving  them  alone. 

" '  Imbeciles/  i.e.  persons  who  are  capable  of  guarding  them- 
selves against  common  physical  dangers,  but  who  are  incapable  of 
earning  their  own  living  by  reason  of  mental  defect  from  birth  or 
from  an  early  age. 

"  '  Feeble-minded,'  i.e.  persons  who  may  be  capable  of  earning  a 


468  INTEMPERANCE  AND  INSANITY 

living  under  favourable  circumstances,  but  are  incapable  from 
mental  defect  existing  from  birth  or  from  an  early  age :  (a)  of 
competing  on  equal  terms  with  their  normal  fellows  ;  or  (b)  of 
managing  themselves  and  their  affairs  with  ordinary  prudence. 

" '  Moral '  imbeciles,  i.e.  persons  who  from  an  early  age  display 
some  mental  defect  coupled  with  strong  vicious  or  criminal 
propensities  on  whom  punishment  has  little  or  no  deterrent 
effect."  i 

767.  Or  consider  "  The  very  good  definitions  submitted  to  us 
by  Sir  James  Crichton-Browne,  of  the  *  imbecile  '  and  the  *  feeble- 
minded '  "  which  "  do  not  turn  on  the  '  capacity  of  earning  a  living, 
but  have  in  some  measure  to  define  the  child  by  anticipation,  by 
standards  applicable  to  a  later  time  of  life  than  early  childhood, 
such  as  prudence,  independence,  and  self  control,'  or  *  taking  care 
of  himself  in  the  common  affairs  of  life.' "     These  definitions  are  : 
— "  An  imbecile  is  a  person  who,  by  reason  of  arrested  development 
or  disease  of  the  brain  dating  from  birth  or  early  years,  has  the  use 
of  his  observing  and  reasoning  faculties  so  restricted  as  to  in- 
capacitate him  for  education  in  the  ordinary  sense  or  for  taking 
care  of  himself  in  the  common  affairs  of  life,  and  who  in  appearance 
and  manner  generally  evinces  his  mental  short-comings. 

"  A  feeble-minded  person  is  one  who,  by  reason  of  arrested 
development  or  disease  of  the  brain  dating  from  birth  or  from 
some  age  short  of  maturity,  has  his  reasoning  faculties  partially 
weakened,  so  that  he  is  slow  or  unsteady  in  his  mental  operations, 
and  falls  short  of  ordinary  standards  of  prudence,  independence, 
and  self-control. 

"  The  moral  imbecile  is  a  person  who  by  reason  of  arrested 
development  or  disease  of  the  brain  dating  from  birth  or  early 
years  displays  at  an  early  age  vicious  or  criminal  propensities 
which  are  of  an  incorrigible  or  unusual  nature,  and  are  generally 
associated  with  some  slight  limitation  of  intellect."  2 

768.  Both  these  descriptions  imply  incapacity  to  learn.     Those 
furnished  by  the  Royal   College  of  Physicians,  however,   merely 
describe  the  social  and  material  consequences  of  the  defect  rather 
than   the   defect   itself — consequences   which    might   conceivably 
arise  from   lunacy,  or   mere  "  backwardness "  due   to  illness,   or 
exceptionally    bad   training.     Sir    James    Crichton-Browne   goes 
deeper,  for  while  he  also  describes  the  effects,  he  attributes  them  to 

1  Report  of  the  Royal  Commission  on  the  Care  and  Control  of  the  Feeble-minded, 
vol.  viii.  p.  188. 

2  Op.  cit.y  vol.  viii.  p.  189. 


DEFINITIONS  OF  IMBECILITY  469 

a  weakening  of  the  observing  and  reasoning  faculties  due  to 
disease  of  the  brain  or  the  arrested  development  (of  a  faculty  not 
mentioned,  and  due  to  a  cause  not  named).  There  is,  however,  no 
evidence  that  the  observing  faculties  of  imbeciles  are  defective  ; 
their  senses  are  usually  as  acute  as  the  normal,  and,  apparently, 
they  are  as  much  guided  by  them  as  other  animals.  But  they 
cannot  store  their  observations.  Their  reasoning  faculties  are 
defective  only  because  reason  itself  is  an  '  acquirement ' — only 
because  they  cannot  gather  sufficient  materials  for  complex  thought 
nor  learn  to  use  skilfully  even  such  materials  as  they  do  gather.  The 
defect  is,  as  I  say,  essentially  an  incapacity  to  profit  by  experience, 
an  initial  lack  or  subsequent  failure  of  memory,  which  prevents  the 
imbecile  learning  and  retaining  all  that  the  normal  person  learns 
and  retains  from  infancy  forwards.  I  include  failure  of  memory 
because  there  does  not  appear  any  good  reason  for  the  arbitrary 
limitation  of  the  term  feeble-minded  to  "  arrested  development  or 
disease  of  the  brain  dating  from  birth  or  from  some  age  short  of 
maturity."  Take  away,  as  by  injury,  from  the  normal  adult  all 
that  he  has  learned  and  at  once  he  becomes  an  imbecile.  Failure 
of  memory  in  the  aged,  whereby  stored  experience  is  lost,  produces 
precisely  the  same  effects  as  congenital  defect.  The  individual 
becomes  equally  *  incapacitated  for  education  or  of  taking  care  of 
himself,'  and,  as  a  fact,  is  taken  care  of  by  his  friends  or  the  State 
in  just  the  same  way  as  a  congenital  imbecile. 

769.  A  better  description  occurs  in  a  Statement  on  Heredity  in 
Relation  to  Feeble-mindedness,  written  by  Sir  E.  Ray  Lankester  at 
the  request  of  the  Commission.  "  There  is  every  reason  to  regard 
this  condition  as  a  case  of  atavism — a  relapse  to  a  primitive 
animal  condition  of  cerebral  activity — memory,  and  with  it  self- 
control  (depending  very  closely  as  it  does  on  memory),  is  defective. 
Some  savage  races  (e.g.  Australian  blacks)  are — as  compared  with 
more  highly  developed  races — normally  in  a  condition  of  feeble- 
mindedness.1 

"Such  throwing  back  in  brain  character  among  the  more 
advanced  races  of  man  is  certainly  transmitted  to  offspring,  and 
there  seems  no  properly  based  argument  for  the  view  that  feeble- 
mindedness is  not  always  congenital.  In  most  cases  it  can  be 
shown  (90  per  cent,  of  carefully  examined  cases)  to  be  due  to 
1  I  think  it  would  be  hard  to  prove  this  statement  concerning  Australian 
natives.  A  school  of  native  children  once  obtained  the  first  place  in  an  Australian 
colony,  and  most  people  (e.g.  Sir  John  Cockburn,  who  told  me  personally)  who  have 
personal  knowledge  of  the  blacks  rate  their  natural  intelligence  very  high,  and 
suppose  that  training,  not  incapacity,  has  made  them  savages  of  a  low  type. 


470  INTEMPERANCE  AND  INSANITY 

hereditary  taint,  although,  as  in  other  cases  of  reversion,  it  may 
from  time  to  time  appear  as  a  '  sport,'  that  is  to  say,  without  any 
history  of  parental  taint."  x 

770.  In    other   words   imbecility   is   both   a   reversion    and    a 
mutation.     "  A  little  thought  renders  it  evident  that  the  feeble- 
minded person  is  always  one  with  a  defective  memory.  ...  In 
effect   and   in    fact   the   feeble-minded  person  is  an   instance  of 
reversion  to  a  pre-human  mental  state.     But  the  reversion  is  not 
complete ;  for  while  he  loses  some  part  of  his  power  of  profiting 
by  experience,  he  regains  no  part  of  the  lost  power  of  being  guided 
by  instinct.     Therefore  he  is  correspondingly  helpless  as  compared 
with  a  lower  animal.     The  instincts  (e.g.  sexual)  which  normal 
human  beings  still  possess  often  appear  unduly  prominent  in  him, 
but  only  because  he  cannot  learn  to  control  them."  2 

771.  But  if  imbecility  is  a  mutation,  the  reproduction  should 
tend  to  be  Mendelian.     It  should  be  patent  or  latent  in  descendants. 
It  "  is  a  sharp  contrast  to  normality.     Here,  then,  apparently  we 
have  an  explanation  of  the  well-known  fact  that  while  the  children 
of  a  defective  may  all  be  normal,  yet  amongst  the  descendants 
may  appear  individuals  who  are  defective."3    The  Royal  Commission 
states  in  its  Report,  "  In  this  connection  the  probable  nature  of  the 
swamping  is  of  some  importance.     Speaking  generally,  the  trend  of 
the  evidence  indicates  that  the  offspring  of  feeble-minded  persons  are 
either  apparently  normal  or  distinctly  feeble-minded.     In  the  same 
family  occur  both  types,  the  same  person  may  have  both  normal 
and    feeble-minded  offspring  and  descendants ;    the  defect  may 
skip  one  or  more  generations  and  appear  later.     It  would  appear, 
therefore,  that  the  swamping  may  be  due  not  so  much  to  a  gradual 
obliteration  of  the  defect  by  a  blending  with  normality,  as  to  its 
becoming  latent  or  overlaid  by  the  latter.     It  would  seem  also 
that  the  probability  of  its  re-appearance  amongst  descendants  is  in 
some  degree  proportionate  to  the  frequency  with  which  it  has 
occurred  amongst  ancestors."  4     It  seems,  then,  that  the  inheritance 
of  imbecility  is  comparable  to  that  of  such  a  trait  as  eye-colour. 
We  saw  that  black  eye-colour  is  strongly  dominant  over  one  of  a 
lighter  shade,  but  that  after  two  or  more  infusions  of  the  latter 
(that  is,  after  the  lighter  shade  is  derived  in  a  patent  or  latent 

1  Op.  cit.,  Appendices,  vol.  v.  p.  247. 

2  Op.  cit.,  Note  on  the  Hereditary  Transmission  of  Mental  Deficiency,  by  G. 
Archdall  Reid,  Appendices,  vol.  v.  p.  247. 

3  Note  on  the  Hereditary  Transmission  of  Mental  Deficiency,  by  G    Archdall 
Reid,  vol.  v.  p.  248. 

4  Op.  cit.,  vol.  viii.  p.  184. 


THE  INCREASE  OF  INSANITY  471 

condition  through  both  parents)  it  tends  to  be  reproduced  by 
descendants.  So  also  normality  appears  strongly  dominant  over 
imbecility ;  but,  when  the  latter  is  derived  through  both  parents, 
normality,  like  black  eye-colour,  becomes  less  dominant  and  the 
alternative  condition  tends  to  be  reproduced — to  become  patent. 

772.  In  every  civilized  country,  during  the  last  half  century, 
the  number  of  persons  registered  as  insane  has  increased  out  of 
all  proportion  to  the  increase  of  the  general  population.  For 
example,  in  Ireland,  "  while  one  person  in  every  657  of  the  popula- 
tion was  registered  as  insane  in  the  year  1851,  the  proportion  had 
risen  to  one  in  178  in  1901. "l  There  is  now  one  officially  known 
lunatic  to  301.32  individuals  of  the  general  population  as  against 
one  to  335  nine  years  ago,  and  one  to  536  in  1859." 2  "From  1st 
of  January  1858  to  ist  January  1908  the  total  number  of  lunatics 
officially  known  to  the  Board  .  .  .  has  increased  from  5,824  to 
16,288,  showing  an  increase  of  10,464.  .  .  .  Since  1858  the  number 
of  lunatics  under  the  protection  of  the  Board  has  increased  180 
per  cent."3  Opinions  differ  as  to  the  cause  of  the  increase.  Some 
of  it,  or  most  of  it,  is  undoubtedly  due  to  a  more  complete 
registration.4  But  probably  some  of  it  is  due  to  actual  multiplica- 
tion.5 We  possess  no  data  on  which  it  is  possible  to  found  a 

1  Macpherson,  Edinburgh  Medical  Journal,  May,  1903,  p.  398. 

z  Fifty-fourth  Report  of  the  Commissioners  in  Lunacy,  1901,  England  and  Wales. 

3  Op.  cit.,  Scotland. 

4  See  The  Fiftieth  Report  of  the  General  Board  of  Commissioners  in  Lunacy  for 
Scotland,  pp.  9  et  seq. 

5  "  Every  one  knows  that  a  large  number  of  the  mothers  of  illegitimate  children 
are  of  weak  intellect ;    that  their  issue  are  frequently  of  the  same  type  ;    that  a 
large  number  of  the  habitual  inmates  of  workhouses  are  of  the  same  low  standard 
of  mind  ;   that  much  of  the  petty  crime  of  this  country  is  committed  by  persons 
below  the  average  in  intellectual  power. 

"  One  of  the  Poor  Law  inspectors  saw  in  a  workhouse  in  Somerset,  an  imbecile 
woman  with  an  illegitimate  imbecile  daughter,  who  had  her  own  illegitimate 
daughter  in  her  arms.  Precisely  the  same  picture  has  been  seen  in  the  County 
of  Cornwall,  and  these  are  but  pictures  in  small  of  a  fact  which  is  to  be  seen  in 
very  many  of  our  workhouses. 

"  But  the  ranks  of  the  insane  as  well  as  of  the  imbecile  are  recruited  from 
the  children  of  the  feeble-minded.  The  fearful  increase  of  late  years  of  insanity 
in  this  country  has  necessarily  created  alarm,  and  I  cannot  but  believe  that  one 
of  the  sources  of  this  fact  is  to  be  found  in  the  imbecility  of  the  parents. 

Sir  James  Crichton- Browne  entirely  agrees  in  this  view.  He  has  written  to 
me  to  the  effect  that  a  terrible  increase  of  insanity  is  going  on,  and  that  it  is  un- 
doubtedly not  merely  due  to  increased  diligence  or  improved  diagnosis,  but  in 
some  measure  to  the  cause  named,  viz.  propagation  of  the  weak-minded,  and 
'  I  am  confident,'  he  adds,  that  permanent  provision  for  imbeciles  of  both  sexes, 
but  especially  girls,  however  costly  it  might  be  in  the  first  instance,  would 
ultimately  result  in  saving  of  the  rates.  In  a  word,  imbecility,  insanity,  bastardy, 


472  INTEMPERANCE  AND  INSANITY 

sure  conclusion.  In  any  case,  however,  the  number  of  the  insane 
is  so  large  that  their  existence  is  a  source  of  vast  misery  and 
hardship  to  very  many  people  and  a  considerable  and  constantly 
growing  burden  to  the  State. 

773.  The  problem  of  the  causation  of  insanity — of  the  causation 
of  its  first  appearance  in  a  line  of  descent — has  been  much  debated. 
Both  imbecility  and  lunacy  are  so  often  reproduced  in  families  in 
which  they  have  once  appeared,  that  it  is  certain  that  there  is 
present,  in  some  instances  at  least,  an  '  innate  and  transmissible ' 
weakness,  a  predisposition  to  one  or  other  form  of  mental  unsound- 
ness.1  Since  lunacy  is  due  to  wrong  learning,  since  the  individual 
is  a  lunatic  because  he  receives  wrong  impressions  from  his 
surroundings,  the  direct  influence  of  the  environment  must 
necessarily,  in  a  sense,  always  play  a  part  in  its  causation.  But, 
since  imbecility  is  due  to  no  learning,  or  a  lack  of  sufficient  learn- 
ing, since  the  individual  is  an  idiot  or  an  imbecile  because  he  does 
not  mentally  acquire  anything  or  enough  from  his  surroundings, 
the  environment  need  not  play  a  part  in  the  causation  of  his 
weakness,2  for  he  may  be  defective  through  a  spontaneous 
variation  which  occurred  in  him  or  in  a  progenitor,  and  which 

and  crime  are  now  paid  for  by  the  ratepayer,  and  any  method  of  diminishing  these 
at  reasonable  cost  must  be  to  his  benefit. 

"  In  the  ruder  state  of  society  which  has  passed  away  little  heed  was  taken 
of  these  unfortunate  children,  and  many  of  them,  no  doubt,  died  comparatively 
early  in  the  struggle  for  existence.  But  we  have  learned  to  think  more  tenderly 
of  the  inferior  members  of  our  race,  and  we  seek  to  protect  them  from  the 
calamities  and  sufferings  to  which  they  are  naturally  exposed,  and  to  preserve 
their  lives  to  the  utmost.  But  in  so  doing,  and  in  so  doing  rightly,  we  incur, 
as  it  appears  to  me,  another  responsibility,  namely,  that  of  preventing,  so  far  as 
we  reasonably  can,  the  perpetuation  of  a  low  type  of  humanity,  for  otherwise 
the  beneficence  of  one  generation  becomes  the  burden  and  the  injury  of  all  succeed- 
ing ones.  The  past  increase  in  the  number  of  lunatics  in  the  country,  to  which 
I  have  already  alluded,  demands  our  most  serious  consideration  of  every  means 
which  can  be  legitimately  used  to  protect  the  race  from  physical  and  mental 
degradation,  and  I  regard  the  segregation  of  imbeciles,  first  in  childhood  and  in 
youth,  and  subsequently  throughout  life,  as  one  of  the  means  which  is  most  open 
to  us"  (Sir  James  Fry,  Evidence  before  the  Royal  Commission  on  the  Care  and 
Control  of  the  Feeble-minded,  vol.  i.  p.  312). 

1  "  Undoubtedly  those  who  have  great  experience  in  the  care  and  supervision 
of  persons  suffering  from  mental   defect  in  these  forms,   such  as   '  idiots  '   or 
'  imbeciles  '    .    .    .    state  that  in  a  very  large  proportion  these  persons  are  the 
offspring  of  mentally  defective  parents  or  are  members  of  families  in  which  other 
nearly  related  members  are  mentally  defective.       Op.  cit.,  vol.  viii.  p.  181. 

2  The  reader  must  bear  in  mind  that  by  the  direct  influence  of  the  environment 
we  mean  such  influence  as  causes  change  in  the  individual  or  the  germ-plasm 
by  acting  directly  on  them.       By  indirect  action  we  mean  selection  or  cessation 
of  selection. 


THE  CAUSES  OF  INSANITY  473 

renders  him  incapable  of  being  so  affected  by  the  environment  as 
to  learn  from  it. 

774.  But  in  another  sense  the  environment — through  violence, 
disease,  alcoholism,  business  worries,  religious  and  sexual  excite- 
ment, and  the  like — may  act  directly  as  a  cause  of  insanity  by 
injuring  the  brain  of  the  sufferer,  or  by  injuring  the  germ-plasm 
contained    in   his   germ-cells.      That    is    to    say,   it   may   cause 
immediate  insanity,  or  be  a  cause  of  a  tendency  to  insanity  in 
descendants.     Cases  of  insanity,  especially  of  lunacy  which  is  a 
disease  of  adult  life,  plainly  traceable  to  injury  or  disease  sustained 
by  the  sufferer  himself,  are  not  uncommon.     We  need  not  dwell 
on  such  instances,  the  causation  being  obvious  ;  the  difficulty  lies, 
not  in  perceiving  the  right  means  of  prevention,  but  in  applying 
them.     Our  interest  centres  in  those  more  obscure  cases  in  which 
the  individual  is  born  insane  (i.e.  more  or  less  incapable  of  learn- 
ing),  or   born   predisposed   to  become   insane  (i.e.  to  become  a 
lunatic.)     Such  cases  are  due  either  to  injury  sustained  by  the 
germ-plasm,  or  to  spontaneous  variation. 

775.  Probably  injury  to  the  brain  occurring  during  intra-uterine 
life  (especially  from  maternal  disease  or  alcoholism)  accounts  for 
some  cases  of  filial  insanity.     Probably,  however,  such  injury  is 
much  more  frequently  a  cause  of  death  occurring  before  birth  or 
shortly  afterwards.     It  may  be  that  the  high  infantile  mortality 
of  urban  as  compared  to  rural  areas  is  due  in  a  measure  to  this 
cause.1     Cerebral  injuries,  whether  acquired  before  or  after  birth, 
are  not  transmissible.     But  germinal  defects  tend  to  be  inherited. 
If  the  variations  which  result  in  insanity  are  usually  spontaneous,  it 
is  beyond  our  power  to  diminish  their  frequency.     We  can  only, 
by  controlling  the  output  of  offspring  by  the  'innately'  insane, 
prevent  their  perpetuation  in  descendants.     If,  on  the  other  hand, 
they  are  usually  caused  (on  the  occasion  of  their  first  appearance 
in  a  line  of  descent)  by  the  direct  action  of  the  environment  on 
the  germ-plasm,  it  may  be  within  our  power,  not  only  to  prevent 
their  perpetuation,  but  also,  by  improving  the  environment,  their 
initial  occurrence. 

776.  But  every  argument  which  tells  against  the  hypothesis 
that  variations  in   general  are  due  to  the  direct   action   of  the 
environment   tells    equally    against    the    hypothesis    that    those 

1  "  It  is  not  necessary  to  dwell  upon  some  other  causes  of  mental  defect,  such 
as  disease  or  accident  in  early  life,  or  even  before  or  at  birth,  operating  through 
injury  to  the  brain.  Cases  of  this  kind  are  recognized  by  all  ;  and  do  not  com- 
plicate the  present  question.  They  occur  in  comparatively  few  instances  (op.  cit.% 
vol.  viii.  p.  185). 


474  INTEMPERANCE  AND  INSANITY 

particular  variations  that  cause  insanity  are  due  to  it.  As  we 
have  noted,  medical  men  have  been  accustomed  to  attribute  all 
sorts  of  filial  defects  to  all  sorts  of  parental  and  ancestral  ill- 
conditions.1  Such  evidence  has  often  been  tendered  to  Royal 
Commissions  and  other  State  inquiries,  and  has  guided  or  mis- 
guided them  in  their  decisions.  The  Report  of  the  Royal  Com- 
mission on  the  Care  and  Control  of  the  Feeble-minded,  the  most 
recent  of  such  State  inquiries,  however,  indicates  a  rapid  and  a 
very  remarkable  change  of  medical  opinion.  After  discussing  the 
evidence  in  detail  and  noting  that  the  weight  of  evidence  is  entirely 
in  favour  both  of  the  spontaneous  origin  and  subsequent  inherita- 
bility  of  feeble-mindedness,  the  Report  continues  : — 

777.  "  The  view  that  injurious  conditions  in  the  environment 
which  affect  the  parent  or  the  child  in  utero  or  after  birth  are  of 
importance  in  the  production  of  feeble-mindedness  needs  some 
further  practical  comment.  The  Memoranda  quoted  in  the  pre- 
ceding paragraph  (549) 2  contain  strong  arguments  against  any 
likelihood  of  such  causes  being  in  any  way  operative  as  causes. 
Many  races  have  been  exposed  to  one  or  other  of  all  the  ill-condi- 
tions which  have  been  alleged  as  causes  of  filial  deterioration.  In 
every  case  the  only  apparent  effect  has  been  to  render  these  races 
capable  of  dwelling  comparatively  unharmed  under  such  conditions. 
It  is  not  to  be  conceived  that  a  race  which  deteriorates  in  every 
generation  can  emerge  from  the  struggle  not  weakened,  but 
strengthened.  Moreover,  almost  conclusive  disproof  of  this 
hypothesis  is  furnished  by  the  facts  submitted  to  us  by  the  medical 
investigators.  These  observers  show  that  feeble-mindedness  is 
practically  as  common  in  rural  as  in  urban  districts,  and  probably 
no  less  prevalent  amongst  the  well-to-do  than  amongst  the  poor. 
It  is  clear  that  if  the  contentions  of  these  witnesses  who  place 
predominant  stress  on  adverse  environmental  influences  as  a  cause 
of  feeble-mindedness  were  just,  there  would  be  an  unquestionable 
prevalence  of  this  affliction  among  the  urban  poor — the  chief 
victims  of  poverty  and  disease."  3 

1  Here  is  an  example.     "  The  Feeble-minded  in  Ireland.     When  a  country  with 
few  industries  except  agriculture  has  its  life  blood  drained  by  the  emigration  of 
the  young  and  fit,  and  when  those  who  remain  are  depressed  by  the  discouraging 
results  of  trying  to  keep  their  heads  above  water  by  tilling  the  soil,  it  is  small 
wonder  that  the  commissioners  charged  with  the  task  of  deciding  what  steps 
should  be  taken  for  the  better  care  and  control  of  the  insane  and  feeble-minded, 
should  have  found  a  grave  state  of  things  to  exist."      (Leading  Article,  British 
Medical  Journal,  Sept.  I2th  1908.) 

2  The  allusion  is  to  contributions  by  Sir  E.  Ray  Lankester  and  the  present  writer. 

3  Op.  cit.,  vol.  viii.  p.  184-5. 


THE  CONTROL  OF  THE  FEEBLE-MINDED         475 

778.  Medical  men  have  often  declared  that  the  insane  tend  to 
be  infertile,  and  that,  therefore,  the  type  tends  to  die  out.     The 
Report   states  : — "  With    regard   to  the   allegation   of  the   small 
ertility  of  mentally  deficient  persons,  the  reports  of  some  of  our 

medical  investigators  and  other  witnesses,  both  medical  and  other- 
wise, tend  to  show  that  although,  as  might  be  expected  for  several 
reasons,  there  is  great  mortality  among  the  children  of  these 
persons,  there  is  also  a  very  marked  degree  of  fertility  and 
urvival  to  adult  age,  especially  among  those  of  the  higher  grades 
who  are  termed  feeble-minded.  Miss  Dendy,  Honorary  Secretary 
of  the  Lancashire  and  Cheshire  Association  for  the  Permanent 
Care  of  the  Feeble-minded,  a  very  experienced  witness,  has  stated 
elsewhere  that  from  her  personal  knowledge  she  can  show  that  the 
ligher  grades  of  feeble-minded  persons  (who  are  the  most 
numerous  and  dangerous)  tend  to  have  very  large  families ;  and 
she  can  prove  this  from  the  detailed  records  of  1,000  cases."  1 

779.  In  conclusion,  the  Commission  sums  up  the  general  effect 
of  the  evidence  as  follows  : — 

"  ( i )  That  both  on  grounds  of  fact  and  theory  there  is  the  highest 
degree  of  probability  that  '  feeble-mindedness '  is  usually  spon- 
taneous in  origin — that  is  not  due  to  influences  acting  on  the 
parent — and  tends  strongly  to  be  inherited. 

"  (2)  That,  especially  in  view  of  the  evidence  concerning  fertility, 
the  prevention  of  mentally  defective  persons  from  becoming  parents 
would  tend  largely  to  diminish  the  number  of  such  persons  in  the 
population. 

"(3)  That  the  evidence  for  these  conclusions  strongly  supports 
measures,  which  on  other  grounds  are  of  pressing  importance,  for 
placing  mentally  defective  persons,  men  and  women,  who  are 
living  at  large  and  uncontrolled,  in  institutions  where  they  will  be 
employed  and  detained  ;  and  in  this,  and  in  other  ways,  kept  under 
effective  supervision  so  long  as  may  be  necessary." 

780.  "  The  question  naturally  rises  whether  it  is  desirable  and 
practicable  that  any  steps  should  be  taken  to  place  obstacles  in 
the  way  of  the  marriage  of  persons  ascertained  to  be   mentally 
defective,  over  and  above  the  restrictions  on  marriage  and  procrea- 
tion   which  would    ensue   from    the   detention   in   institutions  of 
mentally  defective  persons  in  whose  case  such  procedure  is  deemed 
necessary;  and  if  there  be  a  disposition  to  answer  the  question  in 
the  affirmative,  the  problem  must  be  faced,  to  which  of  the  classes  of 
the  mentally  defective  should  such  additional  restriction  be  applied. 

1  Op.  cit.,  vol.  viii.  p.  185. 


476  INTEMPERANCE  AND  INSANITY 

781.  "Such  legislation  would  not  be  an  absolute  novelty  in 
English  speaking  communities;  but  there  is  little  or  no  reliable 
information  as  to  the  practicable  results  of  the  tentative  efforts  in 
this  direction  which  have  been  made  in  New  Jersey  and  elsewhere  ; 
and  it  is  clear  that  such  legislation  however  carefully  restricted 
would  in  effect  operate  less  by  imposing  an  easily   enforceable 
legal    prohibition   than    by  guiding   and    directing   the   advisory 
functions  of    medical   and   other  authorities  and    in    other  ways 
educating  public  opinion  to  the   proper  consideration  of  a  very 
serious  evil. 

782.  "  We  are  of  the  opinion  that  it  would  be  unwise  to  modify 
or  supplement  the  existing  law  with  respect  to  the  marriage  of 
'  persons  of  unsound  mind  '  [z.e.  lunatics].     It  is  perhaps  unnecessary 
to  refer  to  other  objections  to  any  such  proposal  ;  it  is  clear  that 
the  limited  and  often  temporary  nature  of  this  particular  mental 
disability  renders  it  impossible  either  to  prohibit  permanently  the 
marriage  of  such  persons  or  to  set  out  in  practically  useful  legislative 
proposals  the  conditions  under  which  such  marriages  might  take 
place. 

783.  "  No  such  obstacle,  however,  presents  itself  in  the  case  of 
those  persons  who  exhibit  the  congenital  and  incurable  forms  of 
mental  defect  [z.e.   imbecility],   and  we  believe  that  a  legislative 
prohibition   affecting  these  classes  would  have  useful  direct  and 
indirect  effects." 1 

1  Op.  cit.,  vol.  viii  p.  185. 


CHAPTER  XXV 
EDUCATION 

The  most  important  practical  problem  of  biology — Our  power  of  influencing 
mental  growth — Self-education — Formal  education — The  three  aims  of  the 
school-master — Subjects  taught,  and  methods  of  teaching  them — The  teaching 
of  young  children  ;  of  older  children  ;  of  young  adults — Religious  teaching — 
The  religious  attitude  is  an  acquirement — The  antagonism  between  religion  and 
science — Methods  of  teaching  religion — Prejudice  and  superstition — Economic 
and  social  effects  of  methods  of  teaching  religion — Inborn  and  acquired  feeble- 
mindedness and  lunacy — The  teaching  of  the  classics — Scientific  teaching — Science 
teaching — Some  sciences  are  founded  on  few  and  some  on  many  facts — The  former 
are  mainly  interpretative,  the  latter  mainly  descriptive — Systematists — Darwin's 
effort  to  make  biology  interpretative — Description  is  the  warp  and  interpretation 
the  woof  of  science — The  teaching  of  biology — The  importance  of  the  science — 
Conclusion. 


o 


784.  S~^\F  all  the  practical  problems  on  which  the  study  of 
heredity  sheds  a  light,  by  far  the  most  important  is 
that  of  the  education  of  the  young,  if  only  for  the 
reason  that  the  solutions  of  all  other  problems,  if  soluble  they  be, 
depends  on  the  intelligence  of  the  race  that  takes  them  in  hand. 
Here,  since  the  mental  growth  which  the  normal  human  being 
makes  under  the  stimulus  of  experience  is  so  vast,  since  according 
to  the  stimulus  supplied  this  growth  may  take  any  one  or  more  of 
a  thousand  different  directions,  and  since  the  kind  and  amount  of 
stimulus  is  very  greatly  under  the  control  of  the  guardians  of  the 
child,  our  power  for  good  and  evil  is  at  its  maximum.  Training 
may  endow  the  child  with  wide  and  useful  knowledge,  or  with 
knowledge  which,  though  great,  is  narrow  and  useless,  or  it  may 
leave  him  very  ignorant ;  it  may  bestow  on  him  habits,  tones  and 
attitudes  of  mind  which  enable  him  to  utilize  such  knowledge  as  he 
acquires  to  the  utmost  limit  of  his  capacity,  or  which  render  the 
widest  knowledge  and  the  highest  capacity  unavailing.  There  is 
abundant  evidence  that  a  child  of  normal  capacity  may  be  trained 
to  a  degree  of  stupidity  resembling  innate  feeble-mindedness,  or  to 
a  degree  of  wrong-headedness  resembling  insanity,  or,  on  the  other 
hand,  to  a  degree  of  intelligence  which,  relatively  speaking, 
resembles  genius.  We  may  differ,  indeed  men  do  differ  very 

477 


478  EDUCATION 

widely,  in  ideals  of  mental  training  ;  we  may  not  agree  as  to  what 
kinds  of  knowledge  and  mental  habits  are  the  best ;  but  no  one 
will  deny  that  a  knowledge  of  what  may  be,  and  has  been  achieved 
by  mental  training,  and  of  the  means  best  adapted  to  achieve  any 
desired  result,  would  be  a  great  advantage  to  the  teacher.  Every 
one  will  agree  also,  in  theory  at  any  rate,  that  wide  and  useful 
kriowledge  and  high  intelligence  are  desirable  qualities,  and  that 
ignorance  and  stupidity  are  not.  Unfortunately,  useful  knowledge 
and  high  intelligence  are  eulogistic  terms  which  are  applied  by 
different  men  to  very  unlike  things.  For  example,  the  terms  would 
hardly  have  had  the  same  meaning  for  Huxley  and  the  curates 
whose  '  cackling '  he  abhorred.  In  his  opinion  the  curates  were 
ignorant  and  unintelligent ;  in  their  view  his  knowledge  was  not 
right  knowledge,  and  his  intelligence  damnable. 

785.  We  have  seen  that  memory  is  nothing  other  than  a  power 
of  growing,  of  developing  mentally  under  the  stimulus  of  use,  and 
that  on  this  faculty  depends  all  thought,  all  intelligence,  all  mental 
adaptability.  Great  intelligence  must  have  for  its  basis  a  power, 
correspondingly  great,  of  profiting  by  experience;  or,  in  other 
words,  a  great  memory.  Man  is  intelligent  because  his  memory  is 
very  capacious.  It  contains  not  only  such  things  as  words,  scenes» 
events,  and  processes  of  reasoning,  which  can  be  recalled  to 
consciousness,  but  also  dexterities,  habits,  bents,  tendencies,  tones, 
and  mental  attitudes  which  cannot  be  consciously  recalled  or 
pictured  in  the  mind,  but  which  are  every  whit  as  important.  We 
have  seen  also  that,  not  only  our  '  physical '  dexterities,  such  as 
walking  and  the  delicately  co-ordinated  movement  of  the  lips  and 
tongue  in  speaking,  but  also  such  '  mental '  dexterities  as  are 
involved  in  associating,  comparing,  discriminating,  and  reasoning 
depend  on  memory.  Lastly,  we  have  to  see  that,  just  as  the 
instinct  of  sport  impels  the  child  to  play  with  his  limbs  till  he  is 
able  to  use  them  dexterously,  so  a  homologous  instinct  impels  him 
to  play  with  the  contents  of  his  conscious  memory  till  he  is  able  to 
use  them  skilfully.  Probably  this  impulse  to  play  with  the  contents 
of  the  conscious  memory,  to  think,  is  the  most  imperious  instinct 
in  our  nature.  At  any  rate,  it  is  the  one  which  is  the  most  cease- 
less in  its  promptings.  A  man  may  resist  hunger,  or  thirst,  or  love, 
or  sleep,  but  not  for  a  moment  can  he  resist  the  impulse  to  think— 
the  impulse  to  learn  to  use  the  contents  of  his  conscious  memory 
skilfully  and  thereby  store  his  unconscious  memory. 

786.  Prompted,  then,  by  the  instincts  of  play,  curiosity,  and 
imitativeness,  the  child  undertakes  the  earlier  part  of  his  own 


SCHOOLROOM  EDUCATION  479 

education  and  performs  its  task  supremely  well.  This  phase  of 
education,  because  directed  by  instinct,  is  full  of  pleasure  and 
interest,  and  follows  the  same  lines  in  the  children  of  all  races. 
With  the  aid  of  the  hunting  instinct  it  bestowed  on  primitive  man 
almost  all  the  acquirements  that  enabled  him  to  maintain  exis- 
tence. But  as  soon  as  man  became  man,  and  more  especially 
when  he  became  civilized,  labour,  a  new  mode  of  activity  to  which 
he  was  compelled  by  the  environment  he  himself  had  created  but 
to  which  he  was  not  prompted  by  instinct,  and  which,  therefore,  was 
not  pleasurable,  became  necessary.  Labour  is  seldom  associated 
with  pleasure,  unless  interest  is  awakened  by  some  element  of 
sport,  curiosity,  imitativeness,  or  some  other  instinct.  At  first, 
doubtless,  all  labour  was  associated  with  some  instinctive  prompt- 
ings, but  as  civilization  advanced,  as  life  grew  more  complex  and 
labour  aimed  at  ends  more  and  more  remote,  its  instinctive 
promptings  withdrew  further  and  further  into  the  background,  and 
were  replaced  by  motives  derived  from  intelligence.  Through 
labour  men  learned  new  dexterities.  They  fashioned  tools,  and 
learned  to  use  them.  They  invented  a  mode  of  recording  words 
and  thoughts  by  written  symbols  and  learned  to  become  skilful  in 
interpreting  them.  Ever,  as  the  mental  horizon  widened,  toil 
played  a  greater  and  greater  part  in  education.  At  present  our 
children  spend  many  of  their  most  receptive  years  at  such  labour ; 
and  when  we  speak  of  education  we  mean,  as  a  rule,  only  the  toil- 
some part  of  it. 

787.  This  laborious,  or  schoolroom,  training  is  formally  de- 
signed to  achieve  two  aims.     An  endeavour  is  made,  on  the  one 
hand,  to  impart  knowledge  of  a  kind  that  cannot  be  gathered  by 
the  child  during  the  course  of  his  non-laborious  education  outside 
the  schoolroom,  and,  on  the  other,  to  train  the  mind  to  deal  skil- 
fully with  the  ordered  knowledge  thus  acquired,  and  in  this  way 
develop  powers  of  thought  (i.e.  skill  in  thinking)  more  far-reach- 
ing and  accurate  than  could  be  otherwise  attained.     A  third  aim 
to  which  the  schoolmaster  is  supposed  to  devote  attention  while 
he   is  the  immediate  guardian  of  the   child  is  the  formation  of 
'  character.'     '  Character,'  however,  is  not  acquired  with  the  same 
obvious  toil  as  knowledge  and  skill  in  thinking.     It  arises,  more 
or  less  unconsciously,  as  a  reaction  between  the  child's  capacities 
and  the  total  environment,  of  which  the  schoolroom  is  only  a 
part,  though  it  may  be  and  often  is,  an  important  part. 

788.  The  three  aims  of  the  schoolmaster  are  separable  in  theory, 
but  not  in  practice.     If  facts  be  taught  to  the  pupil,  he  tends  to 


480  EDUCATION 

think  about  them ;  and,  according  to  the  way  in  which  he  thinks 
his  character  will  be  influenced  subtly  and  profoundly.  All  arrays 
of  facts  do  not  afford  equal  facilities  for  acquiring  skill  in  thinking. 
Some,  for  example,  the  lengths  of  rivers,  the  heights  of  mountains, 
the  dates  of  history,  and  facts  about  the  bones  and  muscles  of 
animals,  may  be  useful  as  items  of  knowledge,  but  by  themselves 
they  afford  poor  materials  for  the  play  of  thought.  Others,  like 
the  data  given  in  mathematical  exercises,  may  be  useless  as  items 
of  knowledge,  but  exceedingly  well  adapted  as  materials  for  mental 
gymnastics. 

789.  Facts  are  relatively  useful  or  useless  as  items  of  know- 
ledge and  as  materials  for  creating  powers  of  thought,  not  only 
in  proportion  as  they  are  true  and  afford  exercise  in  hard  thinking, 
but  in  proportion  as  they  do  or  do  not  link  up  with  the  subsequent 
experiences  of  the  learner.     Thus,  since  the  elementary  truths  of 
arithmetic  are  used  almost  every  day  in  our  lives,  they  are  remem- 
bered and  have  a  greater  influence  on  the  mental  career  of  the 
average   individual    than    the  higher  mathematics   he   may  have 
learned ;  for  the  latter,  though  they  require  more  strenuous  think- 
ing, are  seldom  used,  and,  therefore,  being  forgotten,  tend  to  lose 
their  influence.     Again,  facts  as  materials  for  thought  derive  their 
value  for  the  pupil  very  largely  from  the  way  in  which  they  are 
acquired  ;    for  on  this   depends  the  way  in  which  he  will  think 
about   them,  and  the   way   he   thinks    about   them   will  in  turn 
influence  his  whole  habits  of  thought.     Thus  the  facts  of  geometry 
are  comparatively  valueless  if  learned  by  rote,  but  excellent  if  the 
chain  of  reasoning  by  which  they  are  demonstrated  be  understood 
and  assimilated. 

790.  The  teaching  of  bald  collections  of  facts  is  comparatively 
easy.     Any   man,  who  has   a  book   of  reference   and   means  of 
inflicting  pain,  may  force  his  pupils  to  learn  the  dates  of  history, 
the  outlines  of  zoology,  or  the  words  of  a  language.    Unfortunately 
the  ease  and  lack  of  intelligence  with  which  this  kind  of  teaching 
may  be  conducted,  the  little  labour  entailed  on  the  teacher,  and 
its  effectiveness  for  purposes  of  examination  or  other  displays  of 
mere  knowledge,  constitute  a  strong  temptation  for  its  employ- 
ment.    It  is  very  widely  used,  not  only  for  the  tuition  of  little 
children,   but   also   for  that  of  young   men   and  women  on   the 
threshold  of  independent  life.     Indeed  little  children  are  usually 
better  taught  than  older  people.     Their  thinking  processes  are  so 
simple,  their  instinctive  curiosity  and  tendency  to  play  mentally 
with  all  they  learn  so  strong,  that  even  the  inferior  teacher,  taking 


THE  SKILFUL  TEACHER  481 

the  line  of  least  resistance,  finds  himself  joining  in  their  play, 
asking  and  answering  questions,  suggesting  analogies  and  other 
relations;  in  brief,  giving  lessons  in  careful  thinking.  Anything 
so  good  as  the  object  lesson  or  the  kindergarten  system  is  rarely 
found  in  the  tuition  of  older  boys  and  girls.  Moreover,  in  England, 
the  majority  of  children  attend  the  public  elementary  schools,  the 
teachers  in  which  have  been  trained  for  their  functions,  are  under 
strict  and  competent  supervision,  and  know  how  to  make  lessons 
interesting.  It  is  quite  common  for  poor  children  to  prefer  the 
school-term  to  the  holidays. 

791.  A  principal  qualification  of  a  good  teacher  lies  in  his  power 
of  interesting  his  pupils,  a  thing  that  can  be  done  only  by  arousing 
their  emotions,  their  instincts,  or  the  imitation  instincts  which  the 
teacher  helps  to  create.     Rewards  and  punishments  may  be  made 
the   means,  but   a  much    better   way  is  to   appeal   to   curiosity, 
imitativeness,  and,  above  all,  to  that  strongest  of  instincts  which 
impels   us   to  play  with   the   contents   of  our  memory,   and   so, 
by   ascertaining   the   relations,    particularly  the   causal   relations, 
between  the  objects  of  thought,  to  unify  the  world  our  minds  con- 
struct.    If  the  teacher  is  dexterous,  curiosity  will  cause  his  pupils 
to  ascertain  and  store  facts,  imitativeness  will  cause  them  to  copy 
his  own  processes  of  thought,  and  the  instinct  to  play  with  the 
contents  of  memory  will  impel  them  to  become  skilful  in  thinking. 
The  best  of  all  teachers  is  one  who  does  not  merely  state,  nor 
even  explain,  the  relations  between  facts,  thereby  doing  little  more 
than  add  new  facts  to  the  rest,  but  who  so  guides  his  pupils  that 
they  are  led  to  do  their  own  thinking  and  make  their  own  dis- 
coveries.    Both  facts  and  thinking  then  acquire  enhanced  value. 
Not  every  subject  affords  full  scope  to  his  talents.     But  usually  he 
has  some  power  of  choice,  if  only  between  the  parts  of  a  subject, 
and  something  may  be  done  even  with  facts  the  relations  of  which 
are  so  simple  and  obvious  that  they  are  perceived  without  effort 
even  by  children.     Unhappily,  skill  in  teaching  is  rarely  one  of  the 
qualifications  by  means  of  which  the  tutors  who  train  the  children 
of  the   governing  classes   secure  their  appointments.     Doubtless 
many   tutors,  through  private   study   or  because   they   are   of  a 
thoughtful   cast   of  mind,  learn  to  teach  well ;   but   this  ability 
is  not,  as  in  the  case  of  teachers  in  public  elementary  schools 
systematically  fostered  by  compulsory  training. 

792.  Probably,  as  a  body,  the  least  skilful  teachers  are  those 
who  complete  the  training  of  young  men  of  the  professional  classes. 
As  a   rule  they   are   people  who   have   achieved   success   in  the 

31 


482  EDUCATION 

practice  of  some  lucrative  profession,  for  example,  medicine. 
They  have  knowledge,  but  they  are  seldom  young,  and,  consequently, 
in  many  cases  they  are  not  very  capable  of  learning  such  a  new 
thing  as  how  to  teach.  Indeed  they  rarely  have  any  notion  that 
there  is  anything  to  learn.  Doubtless  there  are  amongst  them 
many  'natural'  teachers  whose  processes  of  thought,  through 
constant,  if  unconscious,  self-training,  combined  perhaps  with 
superior  capacity  to  learn  to  think  well,  have  become  so  clear  and 
logical  that  they  are  able  to  present  the  objects  of  study  interest- 
ingly and  suggestively  to  their  pupils.  But  probably  every 
student  of  a  profession  hears  lectures,  attendance  at  which,  though 
compulsory,  is  not  only  a  waste  of  time  but  is  also  positively 
harmful  to  a  developing  and  imitative  mind.  The  method  too 
often  adopted  is,  not  the  Socratic  plan  of  teaching  the  student, 
whenever  possible,  how  to  think  in  order  that  he  may  discover 
what  to  think,  but  that  of  the  Catechism  which  asks  only  stereo- 
typed answers  to  stereotyped  questions.  Among  the  pupils  are 
future  teachers,  and  in  science,  as  in  religion  and  other  human 
affairs,  evil  as  well  as  good  traditions  tend  to  be  perpetuated. 

793.  Except  as  regards   a   supply  of  facts,  some  professional 
courses,  for   example   the  medical,   hardly   attempt   to   continue 
intellectual  development.     It  is  not  reasonable  to  suppose,  however, 
that  the  preparatory  schools  have  already  accomplished  all  that  is 
possible  to  stimulate  the  reflective  powers,  or  that  mere  accumula- 
tion of  knowledge  will  do  it.     Men    who   have  continued  their 
formal   education    for   some   years   after   leaving   school,   usually 
possess  much  greater  knowledge  than  their  less  fortunate  fellows  ; 
but  it  is   not   equally   obvious   that   their  skill    in   thinking   has 
developed  a  corresponding  superiority.     In  brief,  the  teachers  who 
direct  the  concluding  stages  of  professional  education,  having  been 
trained  by  an  imperfect  method,  are  usually  unable  to  do  other 
than  train  their  pupils  by  it.     They  are  compelled  thereto,  not  only 
by  the  requirements  of  examinations  which  have  been  framed  by 
men  like  themselves,  but  by  their  own  attitudes  of  mind.     When, 
as  is  not  unusual,  they  exclaim  that  they  are  able  to  supply  their 
pupils  with  knowledge  but  not  with  brains,  they  condemn  their  own 
methods.     On  the  average  they  deal  with  normal  human  beings  ; 
and  since  '  brains '  grow  under  the  stimulus  of  use,  it  should  be  a 
main  part  of  their  business  to  develop  them. 

794.  It  is,  of  course,  out  of  the  question  to  select  as  teachers 
to   young   men   about   to   enter   a   profession    any   but    its  most 
eminent  practitioners.     It  is  equally  out  of  the  question  to  expect 


MENTAL  HABITS  483 

men  who  have  achieved  distinction  in  any  important  branch  of 
study,  and  who  have,  as  is  often  the  case,  made  considerable 
additions  to  knowledge,  to  acquire  in  middle  or  old  age  the  sort 
of  skill  that  is  considered  essential  in  good  pupil  teachers.  More- 
over, students  who  adopt  a  professional  career  must  acquire  the  data 
on  which  practice  is  founded ;  and  the  array  of  facts  which  have  to 
be  committed  to  memory  is  often  so  vast  that  little  time  is  left  for 
thinking  about  them.  Many  of  the  subjects  in  the  curricula  are 
such  that  the  best  of  tutors  are  forced  to  restrict  themselves  to 
teaching  facts  and  habits  of  close  observation.  Nevertheless,  a  good 
deal  might  be  done  to  awaken  science  teachers  to  a  conviction  that 
the  function  of  higher  education  is  to  impart  more  than  knowledge 
and  habits  of  observation.  Some  of  the  facts  and  subjects  on  which 
students  must  pass  examinations  have  no  bearing  on  practice  and 
might  be  exchanged  for  others  which  place  a  greater  strain  on  the 
reflective  faculties ;  or,  at  least,  the  teaching  of  them  might  be  so 
modified  that  the  reflective  faculties  are  more  exercised  than  at 
present. 

795.  If  we  train  a  man  well  in  any  department  of '  physical' 
activity,  such  as  penmanship  or  cycling,  he  tends  to  become 
particularly  dexterous  in  it.  But  the  influence  of  special  training 
does  not  altogether  end  with  the  acquisition  of  special  dexterity. 
Thus  an  individual  who  has  learned  to  co-ordinate  his  muscles  for 
walking  has  made  a  step  towards  learning  to  co-ordinate  them  for 
cycling.  So,  also,  if  we  train  an  individual  to  think  well  in  any 
sphere  of  c  mental '  activity,  for  example,  chess,  mathematics,  or 
physics,  he  will  not  only  become  especially  skilful  in  it,  but  his 
acquirement  will  tend  to  colour  his  whole  mental  state  by  exerting 
a  greater  or  lesser  influence  in  other  departments  of  thought — a 
greater  influence  in  kindred  departments,  a  lesser  influence  in 
departments  that  are  psychologically  more  remote.  By  themselves 
facts  are  isolated  things  ;  each  fact  must  be  acquired  separately,  and, 
unless  linked  by  thoughts  to  others,  held  separately.  But  mental 
dexterities,  habits,  attitudes,  link  together  inevitably  ;  one  furnishes 
a  stepping-stone  to  another.  Nevertheless,  just  as  we  cannot 
make  a  man  a  good  cyclist  by  teaching  him  to  walk,  nor  even  by 
providing  him  with  plenty  of  bicycles,  so  we  cannot  insure  that  he 
will  be  a  good  thinker  in  any  department  (e.g.  the  ordinary  affairs 
of  life)  by  training  him  in  another  department  (e.g.  mathematics), 
nor  even  by  providing  him  with  the  materials  of  thought,  the  facts, 
in  the  chosen  department.  To  insure  the  best  results  our  teaching 
must  be  direct ;  that  is,  we  must  not  only  provide  the  right  facts, 


484  EDUCATION 

but  we  must  also  train  our  pupils  to  think  about  them  in  the  right 
way. 

796.  To  sum  up :  skill  in  thinking,  like  other  dexterities, 
depends  partly  on  innate  capacity  to  learn,  partly  on  the  amount  of 
practice,  and  partly  on  the  kind  of  practice.  Innate  capacity,  though 
it  varies  with  individuals,  is  a  fixed  quantity  in  each  individual.  But 
the  amount  and  kind  of  practice  is  within  our  control.  We  deliber- 
ately train  young  children  to  think  skilfully,  and  the  younger  they 
are  the  more  direct  is  our  teaching,  the  more  closely  adapted  to  the 
end  in  view  and  the  needs  of  the  subsequent  career.  But  as  they 
grow  older  and  ripe  for  the  attainment  of  higher  grades  of  skill,  we 
tend  to  slacken  our  efforts,  or  to  seek  our  ends  in  a  very  indirect  and 
ineffectual  way.  The  human  being  tends  to  remember  only  impres- 
sive things,  or  those  which  are  hammered  into  his  mind  by  repeated 
experiences,  and  he  tends  to  think  only  of  that  which  interests  him. 
Often,  by  way  of  mental  gymnastics,  in  the  vague  hope  that  the 
youth  will  remember  and  think,  we  supply  him  with  facts  which, 
rightly  used,  might  furnish  excellent  materials  for  thought,  but 
which  we  do  not  impel  him  to  use,  and  which  he  does  not  use  of 
his  own  initiative,  because  by  themselves  they  are  uninteresting  and 
of  such  a  kind  that  his  subsequent  experiences  do  not  keep  them 
in  mind.  We  put  him  on  the  tread-mill  and  expect  him  to  become 
speedy  in  the  race.1 

1 1  remember  a  professor  of  zoology  telling  me  some  years  ago,  that  though 
he  did  his  best  to  convince  his  pupils,  principally  medical  students,  that  acquire- 
ments were  not  transmissible,  his  teachings  were  '  spoilt '  by  the  physicians  and 
surgeons  through  whose  hands  the  young  men  subsequently  passed.  He  quite 
recognized  the  importance  of  the  matter,  and  alluded  sorrowfully  to  the  medical 
evidence  given  before  various  Royal  Commissions  by  former  members  of  his 
class.  His  lectures  consisted  in  more  or  less  detailed  anatomical  descriptions  of 
certain  types — starfish,  sea-urchin,  earthworm,  leech,  cockchafer,  lobster,  dogfish, 
cod,  snake,  rabbit,  and  so  forth — animals  which,  by  way  of  practical  work,  the 
pupils  were  required  to  dissect.  His  examinations  were  designed  to  discover  the 
extent  to  which  these  teachings  had  been  committed  to  memory.  Once  or  twice 
during  a  session  he  mentioned  the  theory  of  evolution  and  expressed  his  agreement 
with  it.  Once  or  twice,  also,  he  told  his  pupils  that,  though  the  matter  was  still 
subjudice,  he  was  convinced  that  acquirements  were  not  transmissible,  and  added 
an  account  of  various  experiments,  such  as  the  amputation  of  rats'  tails.  The 
anatomical  studies  of  his  pupils  were  so  conducted  that  nothing  was  learned  but 
facts,  their  co- existences  and  resemblances — that  one  species  was  related  to  another 
because  such  and  such  structures  were  possessed  by  both,  that  the  lobster  had 
certain  organs  and  the  rabbit  certain  others,  that  the  dogfish  had  no  bones  but 
only  cartilages  in  such  and  such  numbers  and  shapes,  but  that  the  cod  had  bones 
of  which  there  were  just  so  many  in  his  head,  and  that  the  precise  shape  and 
spatial  relations  of  these  bones  were  this  and  that — facts  that  had  no  bearing, 
or  none  at  least  that  he  made  clear,  on  the  problems  of  heredity  which  he 
recognized  as  so  important ;  and,  indeed,  so  little  bearing  on  anything  else  in 


A  NEGLECTED  PROBLEM  485 

797.  The  extent  to  which  thinking  power  may  be  influence!  by 
the  formal  training  received  during  early  manhood  cannot  easily 
be  observed  in  the  individual.    When  trying  to  analyse  the  degree  of 
intelligence  displayed  by  him,  we  do  not  know  what  part  to  attribute 
to  innate  capacity,  what  to  formal  training,  and  what  to  various 
other  influences,  such  as  those  exercised  by  his  companions,  all  of 
which  contribute  to  his  intellectual  development  and  status.     If 
we  meet  a  clever  man  and  approve  the  system  by  which  he  was 
trained,  we  are  apt  to  attribute  his  efficiency  mainly  to  training ; 
if  we  disapprove  of  the  system,  we   tend  to  assign  it  to  innate 
capacity.     Owing  to  lack  of  systematic  inquiry,  this  question  of 
what  is  '  innate  '  and  what  is  '  acquired  '  in  the  human  mind,  though 
the  most  important  of  all  practically,  is  yet  the  most  neglected 
problem  of  psychology.     The  consequent  uncertainty,  combined 
with  the  difficulty  of  ascertaining  the  precise  results  of  this  or  that 
system  of  mental  training  and  then  comparing  them  with  the  results 
obtained  by  other  systems,  has  led  to  a  vast  diversity  of  opinion  as 
to  which  system  is  the  best,  some  authorities  advocating  one,  some 
another,  and  some  holding,  apparently,  that  so  much  is  innate  that 
all  systems  produce  nearly  the   same  results  in  the  end.1     It  is 
possible,  however,  to  overcome  the  difficulty  in  some  measure. 

798.  We  found  that  the  solution  of  the  problem  of  the  causation 

the  medical  curriculum  or  the  affairs  of  everyday  life  that,  when  the  examination 
on  them  was  over,  they  were  promptly  forgotten  by  all  except  the  few  students 
who  adopted  zoology  as  a  profession  or  as  a  hobby.  The  professor's  convictions 
were  countered  by  the  convictions  of  other  professors — of  physiology,  patho- 
logy, medicine,  surgery,  and  the  like.  His  experiments  were  met  by  accounts 
of  other  experiments  (extraordinarily  misinterpreted),  by  details  about  cats, 
almost  as  legendary  as  Bo-Peep's  sheep,  that  had  left  their  tails  behind  them  in 
traps  and  doorways  and  had  borne  tailless  offspring  ever  afterwards,  by  stories 
about  human  mothers  who  had  seen  moving  sights  and  borne  marked  children, 
and  about  consumptives,  alcoholics,  syphilitics,  and  imbeciles  whose  children 
were  similarly  affected.  Their  reasoning  was  founded  on  credulity  and  confusion 
of  thought,  but  'the  students  had  been  so  trained  that  they  were  unable  to  per- 
ceive its  weakness.  But,  if  the  zoologist,  instead  of  stating  his  convictions  or 
appealing  to  evidence  which  his  pupils  could  not  verify,  had  carefully  explained 
the  distinction  between  variations  and  modifications,  pointed  out  the  difficulty 
of  believing  that  the  latter  could  affect  the  germ-plasm  in  such  precise  ways  as  to 
be  reproduced  in  the  child  as  '  innate '  characters,  and  had  then  appealed  to  the 
facts  of  ordinary  experience  and  of  human  evolution  against  disease,  he  would 
have  supplied  his  audience  with  data  and  thoughts  pregnant  and  unforgettable 
because  they  would  have  linked  up  with  subsequent  experiences,  and  with  a 
mental  training  which  would  have  enabled  them  to  appraise  at  their  true  worth 
the  puerilities  of  professors  who  argued,  for  example,  that  "  acquirements  must 
be  transmissible,  for  every  character  must  have  had  a  beginning,  and  therefore 
must  have  been  acquired  by  some  one  who  handed  it  on  to  his  descendants." 
1  See  §  708. 


486  EDUCATION 

of  variations  is  impossible  as  long  as  we  observe  only  individuals, 
but  that  we  are  able  to  arrive  at  definite  and  almost  certainly  true 
conclusions  when  we  compare  races  that  have  evolved  under 
known  but  unlike  conditions,  and  more  particularly  when  we  are 
able  to  compare  the  present  of  a  race  with  its  known  past.  The 
same  method  will  serve  in  the  endeavour  to  ascertain  the  effects 
of  mental  training  in  early  manhood.  We  shall  thus,  if  only  we 
think  carefully  enough,  be  able  to  compare  different  systems  of 
mental  training  and  separate  the  effects  produced  by  them  from 
those  produced  by  the  other  influences  to  which  the  individual  is 
exposed.  All  systems  profess  to  teach,  on  the  one  hand,  know- 
ledge, and,  on  the  other,  right  and  efficient  ways  of  thinking.  The 
amount  and  kind  of  knowledge  imparted  by  any  system  is  easily 
observable.  Our  object,  then,  is  to  ascertain  the  intellectual  effects 
other  than  mere  knowledge — the  kinds  and  qualities  of  the  thinking 
resulting  from  the  principal  methods  of  teaching.  We  shall  see  more 
clearly  than  ever  that,  while  knowledge,  as  is  very  obvious,  results 
from  the  things  that  are  taught,  the  quality  of  the  thinking  depends  in 
a  degree  that  is  rarely  realized  on  the  way  in  which  they  are  taught. 

799.  The  effects  of  religious  teaching   offer   very   favourable 
materials  for  study.     All  sorts  of  religions  have  been  taught,  in 
every  variety  of  way,  to  races  all  over  the  world  and  in  every  stage 
of  culture  and  civilization.     Some  religions  have  been  held  by  the 
same   races   for  many   consecutive  centuries.     Other  races  have 
rapidly  and  repeatedly  changed  their  religions.     Some  religions 
have  been  held  by  many  diverse  races,  while  in  other  cases  sections 
of  the  same  race  have  followed  two  or  more  diverse  religions.     In 
some  countries  the  inhabitants  are  all  of  one  religion,  which  is 
taught  to  every  one  in  much  the  same  way  ;  in  others,  systems, 
strongly  contrasted  in  the  things  they  teach  and  in  the  way  they 
teach,  divide  the  inhabitants.     In  different  times  and  places  the 
same  religion  has  been  taught  by  different  methods.     As  in  the 
case  of  diseases,  the  range  and  diversity  of  the  phenomena  thus 
presented  enable  us,  through  processes  of  analysis  and  comparison, 
to  reach  conclusions  otherwise  unattainable. 

800.  At  this  stage  I  must  beg  the  reader  to   bear  in  mind 
constantly  the  fact  that  we  are  discussing,  not  the  truth  or  untruth 
of  religious  doctrines,  but  only  the  mental  effects  resulting  from 
methods  of  teaching.      If  we  strictly  limit  the  discussion  to  this 
question,  and  if  our  reasoning  be  right,  we  may,  however  much 
we  may  disagree  as  to  religious  doctrine,  be  able  to  reach  an 
agreement   as    regards    method.      At    any   rate,   we   shall   have 


RELIGIOUS  TRAINING  487 

gathered  materials  which  may  help  us  to  agree  ultimately.  Even 
if  doctrines  be  regarded  as  Divine  revelations,  yet  the  ways  in 
which  priests,  parents,  and  schoolmasters  teach  them  are  neces- 
sarily human  devices,  and  therefore  legitimate  subjects  of  criticism. 
It  is  admitted  that  good  teaching  tends  more  than  bad  teaching 
to  create  intelligence  ;  and  a  religion  like  any  other  subject  may 
be  well  or  ill  taught.  Again,  since  few  people  are  able  to  think 
without  bias  of  their  own  faith,  and  since  it  is  probable  that  the 
reader  is  an  average  individual,  may  I  beg  him,  if  I  happen  to 
mention  his  religion,  to  try  to  think  in  terms  of  some  other. 
Thus,  if  I  make  mention  of  the  Christian  sect  to  which  he 
belongs,  let  him  try  to  conceive  some  corresponding  Mohammedan 
sect  and  suppose  we  are  discussing  that. 

801.  All   religious   knowledge  is,  of  course,   acquired,   as   are 
also  the  kinds  of  thinking  and  the  attitudes  of  mind  that  result 
from  religious  teaching.     It  is  because  they  are  universally  recog- 
nized   as   highly  important   acquirements   that   so  much  care  is 
taken  in  teaching  them.     Since  religion  offers  immense  rewards 
and  punishments,  covers  the  whole  field  of  morals,  inculcates  par- 
ticular views  concerning  the  universe,  influences  the  individual  in 
all  his  public  and  private  relations,  and  tends,  therefore,  to  be 
revived  in  his  thoughts  more  often  than  any  other  subject  that  is 
formally  taught,  probably  none  other  so  profoundly  affects  his 
intellectual  status.     But  children,   though  they  may  be   coerced  to 
religious  thoughts  and  observances,  are  comparatively  little  affected  by 
them.     They  are  too  completely  under  the  sway  of  strong  instincts 
which  impel  them  to  thinking  which  is,  at  least,  non-religious  ; 
their   minds   are  very   ductile  and    therefore   incapable  of  those 
passionate  convictions  and  unalterable  mental  attitudes  which  so 
often   characterize    the   adult,  and  which  we  term  perverse  and 
fanactical  in  people  who  differ  from  us ;  their  stage  of  develop- 
ment is  such  that  they  are  but  little  capable  of  appreciating  the 
surpassing  importance  of 'religious  truth/  or  of  being  influenced  by 
religious  motives  in  the  way  that  the  adult  is  influenced.     To  them 
religion  is  but  one  of  the  many  wonderful  things  that  they  learn 
from  the  adult — the  occasion  of  a  story  or  a  lesson,  of  a  game  or 
of  a  labour.     The  fervour  of  the  saint  or  the  dervish,  the  stern 
conviction  of  the  puritan,  and  even  the  hysteria  of  some  sects  is 
not  for  children.     Only  after  adolescence  is  reached  does  religion 
exercise  its  typical  influence. 

802.  Speaking  generally,  in  proportion  as  the  mental  influence 
of  a  religion  is  wide,  the  intellectual  status  with  which  it  is  asso- 


488  EDUCATION 

dated  is  low.  This,  of  course,  does  not  necessarily  imply  that  the 
doctrines  of  all  religions  are  untrue  and  degrading.  If  the  religion 
is  true,  it  may  imply  merely  that  many  of  the  doctrines  taught  by 
it  have,  through  the  advance  of  science,  been  established  on 
verifiable  evidence,  and,  therefore,  have  passed  from  the  category 
of  things  believed  to  be  true  into  that  of  things  proved  to 
be  true — into  that  category  which  it  is  the  hope  of  all  religious 
people  that  their  articles  of  faith  will  be  found  at  the  awakening 
after  death.  They  then  become  a  part,  not  of  *  religious '  truth,  but 
of  that  ordinary  secular  knowledge  which,  when  systematized,  is 
termed  science.  For  their  acceptance  an  "act  of  faith"  is  no 
longer  needed.  Thus,  if  all  the  doctrines  of  Mohammedanism 
were  verified,  they  would  be  distributed  amongst  the  various 
sciences,  and,  since  no  indisputably  verified  fact  is  ever  regarded 
as  a  religious  truth,  the  religion,  as  such,  would  cease  to  exist. 
It  would  be  rejected,  not  by  the  irreligious,  but  only  by  the 
ignorant,  who,  as  a  rule,  would  be  prejudiced  adherents  of  some 
other  faith.  Probably,  too,  the  emotional  tone  of  true  believers 
would  undergo  change.  Verified  truth  is  not  regarded  with 
that  peculiar  devotion  to  which  the  adherents  of  religions  are 
trained.  There  is  no  need  for  it.  Thus,  in  science  heated  con- 
troversies occur  only  about  matters  that  are  doubtful.  No  one 
was  ever  fanatical  about  a  mathematical  demonstration.  It  follows, 
that  as  verified  truth  accumulates,  the  area  covered  and  emotionally 
coloured  by  religion  tends  to  shrink.  For  example,  our  ancestors 
held  as  religious  truth  an  immense  body  of  belief  concerning  the 
visible  universe,  but  nobody  claims  any  part  of  our  present  verified 
knowledge  as  an  item  of  faith,  and,  if  any  of  our  fellows  now  held 
that  the  earth  is  flat,  we  should  think  them  foolish,  not  wicked. 
But  "  when  we  examine  the  general  culture  of  the  savage  we  find 
that  it  is  entirely  religious.  The  savage  not  only  has  religion,  but 
apparently  has  nothing  else." l  The  heavens  and  the  earth,  every 
echo,  rainbow,  and  lightning ^flash,  every  disease  and  accident,  even 
the  things  he  eats,  and  the  rocks  and  trees  he  dwells  under,  are 
interpreted  by  him  in  religious  terms.  Compare  the  area  covered 
by  his  religious  convictions  with  the  shrunken  area  covered  by  the 
modern  Christianity  of  the  more  enlightened  peoples.  In  one 
sense,  then,  science  is  always  antagonistic  to  religion.  Whatever 
is  true  it  tends  to  render  non-religious ;  whatever  is  false  it  tends 
to  overthrow ;  and  invariably  it  tends  to  alter  the  emotional  tone, 

1  The  Rev.  A.  E.  Crawley,  "  The  Origin  and  Function  of  Religion,"  Sociological 
Papers,  vol.  iii.  p.  245,  Macmillan  &  Co.,  1907. 


METHODS  OF  TEACHING  489 

the  mental  attitude.  If  the  reader  doubts  this  statement,  it  would 
be  well  if  he  tried  to  think  of  a  truth  which  has  remained  religious 
after  having  been  verified,  or  of  a  verified  truth  which  he  regards 
with  emotional  devotion. 

803.  Most  religions  have,  or  had,  doctrines  about  the  shape  of 
the  world.     The  ancient  Christian  belief  that  the  world  is  flat  has 
been  abandoned,  and,  therefore,  may  furnish  a  text,  the  discussion 
of  which,  while  permitting  a  measure  of  freedom,  will  arouse  a 
minimum  of  prejudice.     This  'fact,'  that  the  earth  is  flat,  may  be 
taught  in  three  distinct  ways.     First,  it  may  be  stated  to  the  pupil, 
after  the  manner  of  much  science  teaching,  as  an  obvious  truth, 
which  he  may  observe  for  himself  by  looking  at  the  horizon  all 
around   him  ;    so   that,  though  he   is   supplied  with  material  for 
thought  and  not  forbidden  to  think,  no  further  attempt  is  made  to 
awaken  thought  or  to  influence  its  direction  or  quality.      Or,  to 
speak   more  accurately,  while  the  pupil    is   supplied   with   facts 
which  he  usually  learns  to  arrange  according  to  their  co-existences 
and  resemblances,  he  is  not  taught  to  classify  them  according  to 
their   invariable   or    necessary   sequences.      Therefore,   since   his 
notions  as  to  what  constitutes  evidence  and  what  proof  are  not 
derived  from  his  teacher,  and  since  much  of  the  thinking,  indeed, 
nearly  all  the  difficult  thinking,  of  human  beings  is  in  terms  of 
cause  and  effect,  the  main  part  of  his  intellectual  development  is 
neglected.     Examples  of  this  kind  of  instruction,  which  is  little 
more  than  a  storing  of  information,  and  which  is  regarded   by 
modern    educationalists    as    a    necessary    evil    that    should    be 
reduced   to   a   minimum,   are   seen   when   the   lengths   of  rivers, 
the   dates    of  history,   or   the   facts   of    systematic   zoology   and 
botany  are  committed  to  memory.     Facts  concerning  the  shape 
of  the  world   are  so  impressive  and  suggestive  and  tend  so  to 
link  up  with  subsequent  experiences  that,  unlike  many  'scientific' 
facts,  they  are  sure  to  be  remembered   and  thought  about ;  but 
the  use  that  is   made  of  them  by  a  pupil  taught  according  to 
this    system    is    left    more    or    less    to    chance.       The     mental 
attitude  created  is  such  that,  though  the  pupil  is  left  free  to  learn  the 
actual  truth  from  other  people,  he  is  not  very  likely  to  correct  the 
initial  error  himself. 

804.  Second,  not  only  may  the  pupil  be  told  that  the  world  is 
flat,  but,  as  an  essential  part   of  the   teaching,  he  may   also   be 
made   to    proceed    to    a    rigorous    deductive    inference   of    con- 
sequences and  a  comparison  of  these  consequences  with  reality. 
In  other  words,  he  is  taught  to  classify  his  facts  not  only  accord- 


490  EDUCATION 

ing  to  their  co-existences  and  resemblances,  but  more  especially, 
as  in  the  ordinary  teaching  of  mathematics  and  physics,  he  is 
trained  how  to  arrange  them  according  to  their  sequences. 
Acquiring  definite  ideas  as  to  what  constitutes  evidence  and 
what  proof,  he  values  his  facts  and  hypotheses  in  proportion 
as  they  are  capable  of  verification  and  of  being  linked  with 
other  facts  and  hypotheses.  Thus,  given  the  flatness  of  the 
world  as  an  initial  fact,  he  may  be  told  that  it  follows 
necessarily  that,  if  armed  with  a  powerful  telescope  he  stands 
in  clear  weather  on  the  seashore,  a  ship  will  never  sink  below 
the  horizon  but  will  be  visible  from  truck  to  waterline  all 
the  way  to  America,  that  a  ship  that  sails  continually  to  the 
West  will  never  come  back  by  the  East,  that  the  sun  and 
stars  must  revolve  round  the  earth,  and  that,  since  they  are  so 
many,  since  they  rise  and  set  in  slightly  different  places  every  day 
of  the  year,  and  since  their  apparent  positions  in  relation  to  one 
another  are  more  or  less  fixed,  it  is  likely  that  they  must  pass 
beyond  the  edge  of  the  flat  earth  and  not  through  holes  in  its 
surface  ;  and  so  forth.  The  initial  statement  made  to  the  pupil  is 
untrue.  He  will  start  his  reasoning  from  false  premises.  But,  at 
least,  he  will  reason  and  will  treat  his  apparently  established  fact  as 
material  for  thought  and  as  the  starting-point  for  the  acquisition, 
examination,  and  systematization  of  more  facts  and  thoughts. 
Moreover,  facts  and  the  thinking  founded  on  them  are  distinct 
things.  As  was  often  the  case  in  Pagan  Greece,  very  good  thinking 
may  be  founded  on  false  premisses — thinking  so  good  that  presently 
the  premisses  are  likely  to  be  discerned  as  false,  as  not  in  accord 
with  reality.  But,  whether  the  premisses  be  true  or  false,  the  main 
feature  of  this  kind  of  teaching  is  that  it  tends  to  endow  the  pupil 
with  an  acquisitive^  an  open>  a  reflective  habit  of  mind.  Not  only 
is  he  left  free  to  learn  the  real  truth  about  the  shape  of  the  world 
from  others,  but,  because  he  will  try  to  link  up  his  belief  with  so 
many  phenomena,  he  is  apt  to  discover  it  for  himself.  Not  only 
does  he  tend  to  think  freely  and  carefully  about  his  past  experiences, 
but  he  remains  alive  also  to  fresh  experiences,  which,  again,  he  tends 
to  think  about,  and  link  up  with,  and  use  as  a  test  for  that  which 
he  has  already  stored — a  mental  attitude  which  tends  continually 
to  increase  his  store  of  material  for  thought  and  his  skill  in  using 
it.  He  learns  to  remain  a  learner  and  become  a  thinker.  He 
takes  every  possible  means  to  avoid  error.  The  universe  his  mind 
constructs  tends  continually  towards  that  organized  whole  which 
is  the  goal  of  all  good  thinking  and  all  good  science. 


METHODS  OF  TEACHING  491 

805.  We  have  seen  that  a  vast  capacity  and  tendency  to  profit 
by  experience  is  the  distinctive  attribute  of  the  human  being,  and 
particularly    of    the   child.     Through    this    arises    what    we   call 
intelligence.     In  one  sense  the  adult  is  more  intelligent  than  the 
child ;  for,  having  had  greater  opportunities,  he  has  profited  more 
from  experience ;  but  in  another  and  a  very  real  sense,  the  child 
is  the  more  intelligent ;  for,  as  a  rule,  he  is  more  receptive,  more 
capable  of  assimilating  fresh  experience  to  that  already  stored. 
As  may  be  seen  by   comparing  a   Darwin  with  a  Mohammedan 
ecclesiastic,  or  average  men  trained  in  modern  Europe  with  those 
trained  in  mediaeval  Europe  or  in  Thibet,  the  degree  in  which  the 
adult  preserves  the  youthful  tendency  to  reach  out  the  tentacles  of 
the  mind  and  knit  together  the  materials  thus  gathered  depends  on 
the  formation  of  a  HABIT,  which,  in  turn,  depends,  in  great  measurey 
on  the  kind  of  formal  training  he  receives.     The  kind  of  teaching 
we  are  now  discussing,  though  not  especially  employed  for  science 
subjects,  is  usually  termed   scientific    by  modern  educationalists. 
It  was  practised  in  its  highest  perfection  by  the  Pagan  Greeks,  and 
was,  as  it  seems  to  me,  the  source  of  their  greatness.     We  have 
only  to  read,  for  instance,  the  dialogues  of  Socrates,  to  perceive 
how  strenuously  they  strove  to  create  not  only  skill  in  thinking, 
but  also  that  open,  receptive  mind  which  is  its  necessary  accom- 
paniment.    At  any  rate,  every  nation  on  earth  is,  and  has  been, 
great  in  proportion  as  it  has  practised  it.     At  the  present  day, 
owing  to  the  freedom  of  thought  permitted  by  modern  civilization, 
we  all  tend  to  receive,  in  greater  or  lesser  measure,  this  kind  of 
training  from  our  general  surroundings  ;  but  in  our  formal  education 
it  is  used  comparatively  little  except,  as  we  have  already  noted,  in 
teaching  young  children. 

806.  It  has  been  used  only  very  rarely  for  religious  teaching, 
and  can  be  used  for  it  only  when  the  religion  is  in  no  way  opposed 
to  known  truth,  or  when  the  teachers  have  no  dread  that  newly  dis- 
covered truths — deceptions  of  the  devil — will  oppose  it.     If  the 
religion  is  in  any  way  false,  if  it  covers  and  colours  a  wide  area 
of  the  mental  field,  and  if  the  contemporary  science  is  rapidly 
advancing,  the  two  are  apt  to  come  into  sharp  conflict ;  and  then  the 
scientific  method  is  liable  to  be  abhorred  by  some,  at  least,  of  the 
exponents  of  religion.    On  the  other  hand,  when  science  has  made 
but  small  advances,  the  current  religion,  even  if  false,  may  offer  as 
good   an   interpretation  of  observed    phenomena  as  can  be  con- 
ceived, and  therefore  may  be  very  tolerant.     This,  to  an  exceptional 
degree,  was  the  case  in  Pagan  Greece.     The  excellence  of  Greek 


492  EDUCATION 

training  in  habits  of  thought  was  due,  apparently,  to  an  unusual 
combination  of  accidents.  There  existed  an  enthusiasm  for  mental 
development,  the  religion  offered  little  or  no  opposition,  the  supply 
of  verified  and  systematized  knowledge  was  small ;  therefore  the 
teachers  could  train,  and  did  train  their  pupils  in  little  besides 
methods  of  thought.  In  modern  times  the  supply  of  facts  is  so 
enormous  that  the  tendency  is  to  teach  nothing  else — facts  of 
language,  history,  geography,  zoology,  and  the  like. 

807.  Third,  the  *  fact '  that  the  world  is  flat  may  be  conveyed 
to  the  pupil  in  such  a  way  that  he  holds  it,  as  an  article  of  faith, 
with  a  sentimental  devotion  that  has  for  its  correlate  an  active 
dislike  or  blank  disregard  of  all  evidence  that  tends  to  controvert 
it.  Of  course,  all  men  do  not  hold  their  faiths  in  this  way. 
Faith,  even  religious  faith,  may  be  associated  with  an  open  mind. 
But  there  is  evidence  all  around  us  that  men  may  be  taught  to 
hold  it  thus.  This  kind  of  thinking  is  essentially  sectarian,  and 
is  very  different  from  that  which  we  have  just  considered.  It,  also, 
deals  with  the  relation  of  cause  and  effect;  but  the  criteria  for 
evidence  and  proof  are  not  the  same.  The  learner  is  taught  to 
appeal  not  to  reality,  but  to  authority,  and  to  value  his  facts  and 
hypotheses  not  in  proportion  as  they  are  capable  of  verification 
and  of  being  linked  together  by  chains  of  reasoning,  but  in  pro- 
portion as  the  facts  have  been  gathered  in  a  particular  field  (e.g. 
Christian,  Mohammedan,  Hindoo,  experimental)  and  the  hypo- 
theses have  been  formulated  by  particular  persons.  Under 
the  influence  of  such  teaching,  not  only  is  a  given  *  fact ' 
accepted  by  the  pupil,  but  an  attitude  of  mind  is  created  which 
co-religionists  (e.g.  modern  Mohammedans)  describe  as  one  of 
simple  or  steadfast  faith,  but  which  opponents  (e.g.  modern 
Christians)  term  superstitious  or  fanatical.  Both  descriptions  are 
correct.  A  superstition  is  a  religious  prejudice  which  is  fanatical 
when  the  emotional  bias  is  very  strong.  It  is  not  necessarily 
an  untrue,  but  only  an  unverified  belief  held  in  a  certain 
obstinate,  unreasoning  way,  which  renders  the  mind  more  or 
less  incapable  of  profiting  from  fresh  experience.  A  faith  that 
will  be  maintained  in  spite  of  evidence  that  it  is  untrue,  is  both 
simple  and  steadfast,  and  superstitious  and  prejudiced.  Obviously ', 
then,  as  regards  mental  habits,  it  is  not  the  truth  or  untruth  of 
a  doctrine  that  matters,  but  the  attitude  of  mind.  Doubtless,  all 
of  us  hold  many  untrue  beliefs.  They  are  not  prejudices  if  founded 
on  ignorance  or  on  mere  bad  judgment.  On  the  other  hand,  a 
truth,  which  its  pioneers  discovered  because  they  had  open  minds, 


THE  EFFECTS  OF  TEACHING  493 

may  be  held  as  a  prejudice  by  followers  whose  minds  are  closed. 
Thus,  if  evidence  were  now  produced  which  conclusively  proved 
the  flatness  of  the  earth,  it  is  very  certain  that  many  minds,  even 
minds  of  scientific  men,  are  so  trained  that  they  would  cling  to  the 
notion  that  it  is  round  with  unalterable  devotion.  I  think  I  have 
met  people  who  held  the  theory  of  natural  selection  in  this  way. 
The  kind  of  teaching  which  most  commonly  produces  a  faith, 
that  turns  from  opposing  evidence  with  abhorrence  or  contempt, 
is  what  is  usually  termed  dogmatic.  It  is  generally  practised  by 
sects  which  take  a  pride  in  being  *  orthodox ' — in  holding  opinions 
which  are  quite  identical  for  all  the  members  and  every  generation 
of  the  communion. 

808.  It  is  interesting  to  note  how  readily  we  are  able  to 
recognize  as  such  superstitions  and  prejudices  to  which  we 
have  not  been  trained  and  which  conflict  with  our  own  beliefs. 
Thus,  every  Mohammedan  is  able  to  perceive,  not  only  how 
slight  is  the  foundation  of  fact,  or  how  great  the  misinter- 
pretation of  fact,  on  which  Hindoos  have  reared  the  monstrous 
edifice  of  their  faith,  but  also  to  perceive  that  nothing  but 
intense  prejudice  prevents,  if  not  a  recognition  of  the  truth  (the 
doctrines  of  Mohammedanism),  at  least  a  recognition  of  false- 
hood (the  doctrines  of  Hindooism).  If  we  place  irrefutable 
evidence  before  the  ardent  adult  Mohammedan  or  Hindoo,  and 
preach  it  for  half  a  century,  we  shall  not  shake  his  faith  in  the 
least.  Moreover,  and  this  is  the  important  point ',  his  mental  inertia, 
his  habit  of  thought,  extends  beyond  the  articles  of  his  faith.  It 
determines  his  whole  attitude.  It  is  hard  to  interest  him  in  new 
ideas  or  set  him  thinking  on  new  lines.  Thus,  though  he  may  be 
forced  to  perceive  the  advantages  of  a  new  gun  or  some  other 
mechanical  device,  he  will  seldom  invent  or  improve  one.  He  is 
capable  of  patient  labour  on  traditional  lines,  and  even  of  prolonged 
and  passionate  outbursts  of  energy  when  under  the  influence  of 
strong  emotion  ;  but  he  is  quite  incapable  of  that  other  sort  of 
patient  thought  and  sustained  effort,  that  wide  appeal  to  ex- 
perience, that  rigorous  deductive  inference  of  consequences,  and 
that  receptivity,  which  make  individual  men,  or  those  collections 
of  men  we  call  nations,  pre-eminently  human,  thinkers  of  new 
thoughts,  learners  and  discoverers  of  new  truth,  and  therefore 
progressive  and  successful  over  competitors  who  are  worse 
equipped  mentally.  Very  rarely  does  his  race  produce  a  man 
distinguished  in  any  field  of  human  thought  and  endeavour  except 
religion.  Examples  of  his  great  men  are  Peter  the  Hermit  and 


494  EDUCATION 

the  Mahdi.  Great  men  in  fields  of  labour  other  than  religion  are 
invariably  thinkers  of  new  thoughts  ;  and  if,  by  chance,  such  a  one 
appears  in  an  orthodox  environment,  he  is  apt  to  be  treated  with 
derision  or  dislike  as  insane  or  wicked,  and  so  to  perish  unrecognized, 
ineffective,  and  inglorious.  The  children  of  the  orthodox,  on  the 
other  hand,  are  quick  and  receptive,  for,  given  the  opportunity, 
they  are  easily  trained  to  recognize  new  truth.  Plainly,  then,  the 
adult  has  been  made  incapable  of  learning.  He  has  acquired  a 
stupidity  which  is  inborn  in  the  lower  animal  and  the  congenital 
imbecile.  Contemporary  Mohammedanism  and  Hindooism  afford 
examples  of  religions  that  cover  and,  since  they  are  taught  dog- 
matically, colour  so  large  a  portion  of  the  intellectual  field,  that 
a  habit  of  mind  is  created  which  is  carried  into  every  relation  of 
life.  Hence  the  stagnation  of  their  adherents. 

809.  As  compared  to  the  lower  animal  and  the  imbecile,  the 
normal  human  being  is  distinguished  by  his  control  over  his 
instincts  and  passions,  which  prompt  him  as  strongly  and  less 
imperiously.  What  is  true  of  the  normal  man  as  compared  to  lower 
types  is  true  of  the  more  reflective  as  compared  to  the  less  reflective 
man.  If  only  because  the  former  is  more  far  seeing,  he  tends,  on 
the  average,  to  be  more  *  reasonable,'  more  orderly  and  law-abiding. 
Therefore,  open-minded  and  progressive  communities  not  only 
tend  to  secure  improved  governments,  but  they  are  also  more  easy 
to  govern.  Among  them  individual  freedom,  mild  laws,  and  a 
civil  unarmed  police  tend  to  replace  tyranny,  savage  laws,  and  a 
military  government.  Compare  the  social  states  and  the  govern- 
ments of  Morocco,  Turkey,  Persia,  Thibet  and  China,  with  the 
domestic  peace  of  many  Christian  communities,  and  of  Japan 
since  its  type  of  mental  training  changed.  Compare  modern 
*  orthodox  '  Christian  communities  with  those  in  which  a  greater  play 
of  the  reflective  faculties  is  permitted  by  the  religious  teaching. 
Note  the  comparative  statistics  of  murder  and  other  crimes  of 
violence,  the  acts  of  brigandage  and  dacoity,  the  rebellions,  civil 
wars,  and  conspiracies  against  the  established  government,  and  the 
acts  of  tyranny  committed  by  the  government.1  Note,  also,  the 

1  All  sorts  of  hypotheses  have  been  formulated  to  account  for  the  relative 
prevalence  of  crime.  Here  is  a  curious  example  from  a  particularly  sane  book 
(Recollections,  by  David  Christie  Murray,  p.  247).  "  My  sympathies  are  with 
the  old  exploded  prize-ring.  Rightly  or  wrongly  I  trace  the  growth  of  crimes 
of  violence  to  the  abolition  of  that  glorious  institution.  I  want  to  see  it  back 
again,  with  its  rules  of  fair-play,  and  its  contempt  for  pain,  and  its  excellent 
tuition  in  temper  and  forbearance."  Students  of  the  question  should  study 
statistics.  But  they  should  not,  as  is  so  very  common  when  it  is  desired  to 


THE  OUTPUT  OF  GREAT  MEN        495 

output  of  great  men  whose  labours  have  rendered  their  nations 
illustrious.  It  will  be  found,  no  matter  how  fervently  the  priest- 
hood inculcate  a  reverence  for  thrift,  law  and  authority,  that,  of 
any  two  communities,  the  more  orthodox  is  almost  invariably  the 
more  poverty-stricken,  the  more  turbulent,  and  the  more  savagely 
governed.  All  orthodox  communities  are  flourishing  in  proportion 
to  the  number  of  heretics  they  include.  Wherever  the  heretical 
(e.g.  Protestants)  and  the  orthodox  (e.g.  Greek  Churchmen)  mingle 
on  equal  terms,  the  former  tend  to  be  the  more  law-abiding  and  to 
occupy  the  more  responsible  and  lucrative  posts,  whereas  the  latter 
tend  to  become  hewers  of  wood  and  drawers  of  water.  The  great 
men  produced  by  orthodox  communities  are  relatively  very  few, 

demonstrate,  for  example,  the  injurious  effects  of  secular  education,  compare 
material  derived  from  localities  (e.g.  new  colonies)  that  are  undergoing  rapid 
change  with  data  gathered  from  places  where  an  old  order  standeth.  Nor  should 
the  statistics  of  the  country  be  compared  without  reservation  with  those  of  the 
town.  Rural  populations  always  tend  to  be  the  more  law-abiding  (see  §  523). 
Here  are  some  statistics  of  murder  from  an  author  (see  Crime  and  its  Causes,  by 
the  Rev.  W.  D.  Morrison)  who  attributes  crime  to  climate,  but  who  has  neglected 
to  compare  the  relative  amount  of  crime  in  Australasia  and  South  America,  both  of 
which  have  warm  climates : — 


Tried. 

Convicted. 

Countries. 

Population  over 
ten  years  of  age. 

Years. 

Annual 

Per 

Annual 

Per 

100,000  in- 

100,000 in- 

average. 

habitants. 

average. 

habitants. 

Italy      . 

23,408,277 

1887 

3,606 

15.40 

2,805 

11.98 

Austria  . 

17,199,237 

1883-6 

689 

4-01 

499 

2.90 

France   . 

31,044,370 

1882-6 

847 

2-73 

580 

3-87 

Belgium 
England 

4,377,813 
19,898,053 

1881-5 

1882-6 

132 
381 

3.02 
1.  60 

101 
151 

2.3I 
0.76 

Ireland  . 

3,854,588 

1882-6 

129 

3-35 

54 

1.40 

Scotland 

2,841,941 

1882-6 

60 

2.  II 

21 

0.74 

Spain      . 

13,300,889 

1883-6 

1,584 

11.91 

1,085 

8.16 

Hungary 

10,821,558 

1882-6 

625 

5-78 

Holland 

3,172,464 

1882-6 

35 

I.IO 

28 

0.88 

Germany 

35,278,742 

1882-6 

567 

1.61 

476 

1-35 

The  population  of  England  and  Wales  is  now  in  the  neighbourhood  of  thirty-five 
millions.  Probably  the  Anglicans  number  about  fifteen  millions,  the  Noncon- 
formists about  the  same,  while  the  Roman  Church  claims'about  a  million  and  a  half. 
The  prison  population,  March  28,  1906,  was  21,580.  Of, this  total  the  Anglicans 
are  returned  as  contributing  16,089,  the  Nonconformists  1,094,  and  tne  Catholics 
4,397  (Parliamentary  Return  on  Prisons,  Religious  Creeds  of  Prisoners,  April 
1906).  Doubtless,  the  numbers  assigned  to  the  Anglicans  are  too  high  and  those 
to  the  Nonconformists  too  low.  Prisoners,  like  soldiers,  tend  to  "  follow  the  band." 
In  Scotland,  at  the  same  date,  Catholics,  a  small^minority,  contributed  971  to  a 
prison  population  of  2,812. 


496  EDUCATION 

and,  with  scarcely  an  exception,  rebels  against  clerical  authority  or 
actual  defaulters  from  the  faith.  Such,  for  example,  were  Voltaire 
and  the  men  of  the  French  Revolution,  Garibaldi,  Mazzini,  Cavour, 
de  Lesseps,  Renan,  Victor  Hugo,  Jaurez  the  great  President  of 
Mexico,  and  Tolstoi.  If  the  reader  will  consider  the  matter  he 
will  be  able  to  recollect  hardly  a  man,  not  a  cleric,  who  was  both 
orthodox  and  great.  I  can  call  to  mind  only  Pasteur. 

810.  I  feel  sure  that  many  people  will  dissent  from  the  opinion 
that   such  great  social  and  intellectual  differences  as   exist,  for 
example,   between    England   and    Morocco    are   due    mainly   to 
differences  in  the  way  religion  is  taught ;  or  rather,  since  religious 
instruction  tends  everywhere  to  be  of  the  same  dogmatic  type,  to 
differences  in  the  extent  to  which   this   method   of  teaching   is 
influential  in  moulding  the  minds  of  young  adults  and  thus  deter- 
mining their  final  mental  attitudes.     I  can  only  ask  the  reader — 
while  bearing  in  mind  (i)  that  dogmatic  teaching  obviously  tends 
to  close  the  mind  and  to  create  an  unchanging  outlook  on  life,  (2) 
that  teaching  of  this  kind  is  much  more  influential  in  such  places 
as  Morocco  where  nearly  all  the  formal  and  much  of  the  informal 
mental  training  is  religious  than  in  England  where  it  preponderates 
much  less,  where  the  many  divergent  sects  adopt  a  tolerant  atti- 
tude towards  one  another,  where  much  of  the  formal  teaching  of 
other  subjects  is  deliberately  designed  to  create  a  receptive  tone 
of  mind,  and  where  indeed  the  whole  surroundings  are  such  that 
they  tend  to  a  far  greater  degree  to  encourage  independence  of 
thought,  (3)  that  in  proportion  as  dogmatic  teaching  has  been 
influential  the  adherents  of  each  of  the  religions  of  the  world  have 
tended   to   have   much   the  same  social    and    intellectual   status, 
though  in  other  respects  (e.g.  climate)  the  environment  has  often 
been  very  different,  and  (4)  that  in  proportion  as  religious  teaching 
has  excluded  other  subjects,  races  have  been  stagnant  and  bar- 
barous— to  try  to  conceive  interpretations  unlike  the  one  I  have 
suggested.     If  the  facts  be  granted,  only  two  other  suppositions 
are  conceivable,  or,  at  any  rate,  have  been   conceived  with  any 
degree  of  clearness. 

8 1 1.  First,  there  is  the  hypothesis  that  racial  mental  differences 
are  mainly  innate,  and,  therefore,  that  the  social  state  of  Morocco 
differs  from  that  of  England  because  Moors  and  Englishmen  are 
"naturally"  as  much  unlike  mentally  as   physically.     We   have 
already  discussed  this  hypothesis  rather  fully,  but  consider  again 
what  it  implies.     It  implies  that  Englishmen  and  Moors  are  incap- 
able of  becoming  alike  mentally,  and,  therefore,  that  there  is  no 


DOGMATIC  TRAINING  497 

hope  that  Moors  will  form  a  civilized  community  except  after  ages 
of  selective  elimination  ;  in  other  words,  it  implies  that  they  are 
now  as  a  nation  so  incapable  of  learning  as  to  be  extremely 
feeble-minded  in  the  technical  sense.  All  orthodox  Mohammedan 
communities,  in  proportion  to  their  orthodoxy,  in  proportion  as 
their  faith  is  steadfast  and  fanatical,  exhibit  much  the  same  social 
phenomena.  Amongst  them  are  descendants  of  the  Pagan  Greeks, 
who,  also,  as  well  as  most  Hindoos  and  Buddhists,  must  be  feeble- 
minded. How,  in  that  case,  shall  we  explain  the  fact  that  a  few 
generations  back,  during  the  middle  ages,  the  ancestors  and  co- 
religionists of  these  same  Moors  were,  in  Spain,  far  more 
enlightened,  progressive,  and  orderly  than  our  own  contemporary 
ancestors  ?  We  derive  the  beginnings  of  modern  science  from  them. 
During  our  own  Dark  Ages  Europe  was  in  a  state  of  social  and 
intellectual  stagnation,  perpetual  foreign  war,  and  domestic  disorder 
identical  with  that  of  Morocco  of  to-day.  If,  then,  the  social  state 
depends  on  innate  racial  characteristics,  what  caused  the  rapid  and 
tremendous  change  that  occurred  at  the  Reformation  in  some  of  the 
countries  of  Western  Europe  ?  At  that  time  the  various  peoples 
turned  from  the  teachings  of  an  infallible  church  to  that  of  a  book 
which,  it  is  true,  they  believed  infallible,  but  on  which  each  man 
exercised  his  wits  and  which  he  interpreted  in  his  own  way. 
Hence  the  diverging  heresies,  the  clashing  sects,  which  in  them- 
selves were  indications  of,  and  conduced  to,  divergent  and 
independent  thought.  Was  the  greatness  of  the  Greeks  and 
Romans  at  a  time  when  the  teaching  tended  to  develop  the 
reflective  faculties  due  to  race,  and  their  decline  when  the  teaching 
tended  to  crush  independent  thought  due  to  race  also  ?  How  did 
it  happen  that  the  tiny  community  of  Athens,  which  in  the  former 
period  produced  more  really  great  thinkers,  poets,  historians, 
philosophers,  and  the  like,  and  more  great  men  of  action — who  of 
necessity  were  men  of  great  thought  also — than  all  Europe  during 
its  Dark  Ages,  never  again  produced  any  ?  Did  the  Chinese  achieve 
civilization  because  they  were  less  feeble-minded  than  their  con- 
temporaries ?  Have  they  stagnated  for  centuries  because  they  are 
more  feeble-minded  ?  Were  the  Japanese  feeble-minded  half  a 
century  ago  ?  Are  they  no  longer  so  ?  How  is  it  that,  except 
when  the  teaching  is  more  liberal  or  less  liberal  than  the  ordinary, 
the  adherents  of  each  religion,  who  may  be  of  many  diverse  races, 
are  so  much  alike  mentally,  but  so  dissimilar  from  the  adherents 
of  other  religions  even  when  of  the  same  race  ? 

812.  Whether,  or  not,  connected  as  cause  and  effect,  there  can  be 
32 


498  EDUCATION 

no  doubt  that,  in  proportion  as  the  prevailing  religious  teaching 
tends  to  create  a  habit  of  prejudiced  thinking,  races  are  stagnant 
and  turbulent.  Must  we  suppose,  then,  that  inferior  races  tend 
'  naturally '  to  follow  *  orthodox '  religions  ?  But,  if  that  is  so,  then, 
once  again,  what  was  the  origin  of  the  astonishing  germinal  change 
which  caused  the  Pagan  Greeks  and  Romans  to  embrace  orthodox 
Christianity  and  the  progressive  Protestant  nations  to  abandon  it  ? 
No  one,  not  a  fanatic,  denies  the  sincerity  of  the  great  majority  of 
the  ecclesiastics  of  every  religion.  How  does  it  happen  that 
ecclesiastics,  especially  those  of  the  more  '  orthodox '  religions  and 
sects,  have  ever  as  a  body  resisted  new  truth  more  strenuously  than 
the  laity  ?  They  are  of  the  same  race,  but  they  have  been  much 
more  carefully  trained  dogmatically.1  Most  people  place  a  high 
value  on  religious  teaching  and  education  generally,  but  of  what 
value  is  any  sort  of  teaching  if  '  nature '  be  so  powerful  as  to  be 
the  main  source  of  racial  and  social  differences  ?  Moreover,  if  the 
human  being  is  so  mentally  blocked  out  by  '  nature,'  in  what  par- 
ticular does  he  differ  from  the  lower  animal  mentally  ?  It  cannot 
be  by  reason  of  superior  educability. 

813.  Second,  there  is  the  hypothesis  that  the  actual  doctrines, 
the  actual  '  facts/  taught  by  religions  are  the  source  of  the  mental 
peculiarities  of  their  adherents.  Within  limits,  this  is  true,  no 
doubt.  If  a  child  be  taught,  for  example,  that  the  world  is  flat,  he 
will  have,  no  matter  how  well  trained,  some  difficulty,  especially  in 
adult  life  when  his  receptive  powers  are  beginning  to  wane,  in 
changing  to  a  conviction  that  it  is  round.  A  man,  who  believes  all 
the  fiction  taught  by  Fetishism,  cannot  well  be  other  than  a 

1  The  whole  atmosphere  of  modern  civilization,  like  that  of  Pagan  Greece 
and  Rome,  is  antagonistic  to  rigid  orthodoxy.  The  various  sects  now  mingle 
freely,  almost  every  one  can  read,  and  to  every  one  who  is  able  to  read  is  accessible 
a  voluminous  literature  crowded  with  diverse  opinions.  Some  freedom  of  thought 
is  inevitable.  Religion  may  nourish  in  this  atmosphere,  as  witness  the  continual 
growth  in  England  and  America  of  ardent  Nonconformist  sects  which,  notwith- 
standing their  fervour,  permit  considerable  latitude  of  belief.  But  orthodoxy 
perishes,  as  witness  the  enormous  secessions  from  the  Roman  church  amongst 
the  more  enlightened  peoples  of  the  Continent,  and  the  fact  that,  in  spite  of  a 
stream  of  immigration  which  has  been  flowing  for  many  years,  the  Catholic 
population  of  Great  Britain  and  the  United  States  does  not  increase  proportionately. 
The  doctrines  of  Catholicism  are  not  demonstrp.bly  less  true  than  those  of  Pro- 
testant sects.  It  seems  evident,  then,  that  the  mental  atmosphere  created  by 
the  method  of  teaching  is  the  cause  of  the  decay  of  the  former  ;  and  the  fact  that 
the  ecclesiastics  of  the  more  rigid  churches  persist  in  maintaining  a  mental  environ- 
ment which  renders  the  prevalence  of  their  own  doctrines  difficult,  is  a  conspicuous 
instance  of  incapacity  to  profit  from  experience.  The  Greek  church,  also,  is 
beginning  to  suffer.  Christianity  loses  fewer  adherents  through  Anglican  teaching. 
Nevertheless,  Nonconformity  has'gained  largely  from  this  comparatively  rigid  sect. 


HABITS  OF  MIND  499 

savage.  Therefore  religions,  in  so  far  as  they  are  false,  are  bars  to 
the  discovery  of  truth.  Nevertheless,  false  beliefs  owe  their 
stability  mainly  to  the  way  in  which  they  are  taught  to  the  pupil. 
For  instance,  it  is  possible  to  teach  Mohammedanism  and 
Buddhism,  as  in  the  case  of  the  Spanish  Moors  and  the  Japanese, 
in  such  a  way  as  to  leave  the  mind  open  to  fresh  evidence.  More- 
over, it  is  not  credible  that  the  Pagan  Greeks  and  Romans  were 
intellectually  greater  than  their  Christian  descendants  of  the  Dark 
Ages  merely  because  their  religious  beliefs  were  more  true,  or  at 
any  rate  less  false.  Nor  is  it  credible  that  the  comparatively 
trifling  doctrinal  differences  which  separate  Protestant  races  from 
their  mediaeval  ancestors,  and,  in  a  lesser  degree,  from  modern 
Catholics  and  Greek  Churchmen,  are  the  causes  of  their  considerable 
social  superiority. 

814.  As  in   the  case  of  susceptibility  to  alcohol,  racial  intel- 
lectual peculiarities  have  been   attributed  to  all  sorts  of  causes. 
For  example,   climate  has  been   alleged   as   a  cause.     But   both 
stagnant  and  progressive  races  have  existed  in  all  the  zones  of 
the   earth,  and  while   climates  change   only    in   geological  time, 
races  may  change  their  characteristics  in  a  generation.     Moreover, 
the  effect  produced  by  climate  is  either  germinal,  or  one  which 
is  *  acquired '  by  every  generation  in  turn.     If  germinal,  it  comes 
under  the  heading  of  innate  ;  if  acquired,  under  that  of  mental 
training.      However,    all    thinking    that    has    connected    mental 
peculiarities  with  climate  has  been   excessively  vague.     Because 
individuals,   whose    race    has   evolved    in    fitness    to   a   cold    or 
temperate  climate,  have  found   a  warm  climate   enervating,  the 
latter,  in  spite  of  natural  selection,  has  been  supposed  to  enervate 
the  race  that  has  evolved  in  it.     On  the  other  hand,  hot  climates 
and   fiery  suns   have   been    thought    to   conduce    to    'hot'    and 
'fiery'    natures.      Equally   absurd    is    the    notion    that    'young' 
races  tend  to  be  vigorous  and  '  old '  races  decrepit,  or  that  there 
is  a  law  of  nature  that  causes  races  to  swing  continually  between 
states  of  high  and   low  efficiency.     Every  human   race  is  of  the 
same  age.     Indeed,  if  it  be  true  that  living  beings  are  genetically 
related,    all    species    known   to   us   are   derived    from    an   equal 
antiquity. 

815.  To   sum    up: — the  method  by  which  religion  is  taught 
profoundly  affects   mental  development.     If  it  be  such  that  the 
pupil,  as  in  the  case  of  fanatical  Mohammedans,  is  made  to  hold 
his  beliefs  as  a  mass  of  obstructive  prejudices,   then,  no  matter 
what  the   truth   of  the    religion,   it   becomes   a   cause  of   social 


500  EDUCATION 

stagnation  and  intellectual  inefficiency.  The  results  of  such 
teaching,  observable  as  they  are  in  every  age  and  country,  and 
in  connexion  with  almost  every  religion,  are  so  universal  and 
manifest  that  the  relation  of  cause  and  effect  is  certain.  Precisely 
in  proportion  as  the  prevailing  religion  is  used  to  render  the 
mind  incapable  of  estimating  the  value  of  conflicting  evidence  and 
of  assimilating  new  truth,  the  individual  is  rendered  unintelligent 
and  the  race  stagnant  and  lawless.  Such  teaching,  which  every 
trained  teacher  would  condemn  as  abominable  if  used  for  a 
secular  subject,  tends  to  produce  a  condition  of  feeble-mindedness 
which  differs  from  the  congenital  kind  only  in  that  it  has  a 
different  origin  and  is  less  profound  inasmuch  as  it  affects  only 
the  reflective  faculties — the  unconscious,  not  the  conscious,  memory  ; 
skill  in  thinking,  not  ability  in  storing  facts.  Now,  since  children 
are  at  that  stage  of  mental  development  in  which  the  individual 
acquires  the  main  part  of  his  knowledge  and  mental  habits,  it  is 
impossible  to  close  their  minds  permanently.  Thus,  while  it  is 
easy  to  convince  them  of  the  truth  of  any  set  of  religious  doctrines 
'  and  prejudice  them  against  any  other  set,  it  is  almost  as  easy  to 
obliterate  the  impression.  Habits  of  thought  become  permanent 
only  later  when  the  youth  develops  into  the  man,  when  the 
instinctive  open-mindedness  and  receptivity  of  the  child  wanes, 
and  is  replaced  by  a  habit  of  being  open-minded  or  the  reverse. 
Consider  how  small,  speaking  relatively,  would  be  the  intel- 
lectual ill-effects  of  Mohammedanism,  Hindooism,  or  any  other 
religion  which  we  believe  to  be  false,  if  the  method  of  instruction, 
even  if  faulty  for  children,  were  good  when  adults  were  taught. 

816.  I  have  discussed  religious  teaching  only  in  order  to 
demonstrate  the  truth  that  it  is  as  necessary  to  bestow  attention 
on  the  thinking  faculties  of  young  adults  as  on  the  increase  of 
their  knowledge.  The  years  during  which  the  youth  changes 
into  the  man  are,  from  the  standpoint  of  mental  development, 
the  most  important  of  all ;  for  at  that  period  the  mental  habits, 
like  the  physical  parts,  tend  to  settle  into  relative  stability. 
To  achieve  the  best  results  we  must  not  only  train  little 
children  to  think  well,  but  we  must  continue  the  process  to  the 
latest  stage  possible.  As  we  use  the  child's  knowledge  for  a 
foundation  on  which  to  build  the  larger  knowledge  of  the  adult, 
so  we  should  use  his  mental  skill  as  a  stepping-stone  towards  the 
acquirement  of  greater  powers  of  thinking.  It  is  agreed  on  all 
hands  that  a  good  educational  system  must  teach  knowledge  and 
mental  skill  which  will  be  useful  in  the  widest  sense  to  the  pupil — 


SCIENTIFIC  TEACHING  501 

useful  not  merely  in  this  or  that  occupation,  but  in  bestowing 
general  intellectual  power.  Knowledge,  and  skill  in  using  it,  are 
useful  only  when  they  link  up  with  the  experiences  of  the  sub- 
sequent career ;  that  is,  when  they  are  actually  useful  in  themselves, 
or  when  they  serve  as  a  ladder  towards  the  acquirement  of  a  more 
extended  and  directly  useful  knowledge  and  skill.  It  would  be 
folly,  for  example,  to  teach  even  elementary  mathematics  to  one 
who,  were  it  possible,  could  never  be  helped  by  it  in  any  way. 
Therefore,  since  environments  vary,  the  same  instruction  is  not 
always  equally  valuable.  Thus  an  acquaintance  with  Latin  and 
Greek  is  not  as  useful  to-day  as  it  was  four  centuries  ago,  when  the 
former  was  a  '  bread-and-butter '  subject  and  the  only  path  to  know- 
ledge, and  the  latter  the  sole  means  of  reaching  the  higher  planes 
of  thought.  At  present  three  principal  systems  of  mental  training 
are  advocated,  the  so-called  classical,  the  so-called  scientific,  and 
the  scientific. 

817.  The  first  is  classical  in  name  only.  It  consists  mainly  in 
a  formal  teaching  of  the  words  and  the  relations  between  the  words 
of  two  foreign  languages  which  are  no  longer  spoken  ;  a  method  of 
acquiring  a  language  so  unnatural,  and  therefore  uninteresting  and 
ineffective,  that  a  decade  of  toil  confers  on  the  pupil  less  than  was 
acquired  without  labour  by  a  Greek  or  Roman  infant  of  two.  The 
Greek  children  and  young  adults  studied  no  foreign  language,  and 
the  Romans  only  Greek,  and  that  only  when  their  greatness  was 
beginning  to  wane.  It  may  be  doubted  whether  the  classical 
system  of  verbal  signs  contributed  appreciably  to  the  quality  of 
the  thoughts  of  which  they  were  the  means  of  expression.  On  the 
contrary,  it  is  probable  that  good  thinking  needed,  and  therefore 
invented,  good  means  of  verbal  expression.  Classical  literature  can 
teach  modern  man  nothing  about  the  universe  his  mind  constructs 
except  some  valuable  human  history.  Its  beauty  is  very  great,  and, 
considering  the  limited  knowledge  of  the  ancients,  the  thinking  it 
reveals  quite  the  most  skilful  known  to  us.  But,  judging  from 
results,  such  instruction  in  Greek  and  Latin  as  is  given  to  boys,  and 
even  to  older  pupils,  does  not  very  commonly  awaken  a  very  keen 
appreciation  of  the  beauty  or  bestow  great  skill  in  thinking.  More- 
over, the  thoughts  have  all  been  expressed  in  English  by  scholars 
with  at  least  as  much  precision  as  is  possible  to  the  learner.  Doubt- 
less, since  English  is  in  part  derived  from  Latin,  a  knowledge  of  the 
latter  helps  us  somewhat  to  an  understanding  of  the  former ;  but 
the  benefit  is  hardly  so  marked  as  to  justify  years  of  labour ;  and 
just  as  it  was  anciently  possible  to  speak  and  write  good  Greek 


502  EDUCATION 

and  Latin  without  a  profound  knowledge  of  the  derivations  of  the 
words,  so,  in  the  case  of  English,  it  is  still  possible.  While  con- 
structing Greek  and  Latin  sentences  or  translating  them  into 
English,  the  student  is  forced  to  think  strenuously.  Doubtless,  he 
derives  benefit  from  this  mental  gymnastic  ;  but  the  skill  achieved 
is  of  a  very  special  kind.  It  does  not  link  up  very  obviously  with 
anything  in  the  subsequent  career  of  most  students.  That  is  to 
say,  the  teaching  is  extremely  indirect.  In  any  case  classical 
teaching  is  as  the  poles  apart  from  that  which  was  practised  when 
Greece  and  Rome  furnished  examples  of  mental  training  for  all 
time.  Modern  classical  scholars  are  often  remarkably  indif- 
ferent to  science ;  but  it  is  certain  that  the  Pagans,  active- 
minded  and  filled  with  intense  curiosity,  would  have  hailed  our 
science  with  rapture,  would  have  taught  it  to  their  young  men, 
and,  above  all,  would  have  taught  them  how  to  think  about  it 
in  such  a  way  as  to  turn  it  to  the  best  intellectual  and  practical 
account. 

8 1 8.  The  expression  'scientific  teaching'  is  used  with  two  very 
different  meanings.     On  the  one  hand  it  implies  tuition  so  given 
that  the  pupil  is  stored  with  knowledge  and  skill  that  develop  his 
intellectual  powers  to  the  utmost.     This  kind  of  teaching,  which 
is  scientific  in  the  sense  that  means  are  consciously  and  effectively 
adapted  to  achieve  clearly  recognized  ends,  need  not  deal  with  the 
data  of  any  of  the  sciences.     But,  since  science  is  nothing  other 
than  verified  and  classified  truth,  since  it  deals  with  reality,  since 
many  of  its  problems  are  sufficiently  abstruse  to  afford  exercise  in 
strenuous  thinking,  and  since  the  pupil  who  learns  to  think  well 
will  be  able  to  link  up  much  of  his  scientific  knowledge  with  the 
experiences  of  his  subsequent  career,  it  probably  affords  the  best 
materials  for  the  general  culture  of  young  adults.     On  the  other 
hand,  the  expression  is  often  used  to  imply  nothing  more  than 
instruction  in  the  data  of  one  or  more  of  the  sciences  of  such  a 
kind  that  little  is  required  from  the  pupil  save  recollection  and 
observation.     This  kind  of  tuition  is  sometimes  termed  'science 
teaching,'  a  description  which  is  valuable  as  marking  a  distinction 
of  real  importance. 

819.  We  saw  that  some  sciences,  for  example  systematic  zoo- 
logy and  botany,  are  based  on  facts  that  are  patent  to  observation, 
whereas  nearly  all  the  facts  on  which  others,  for  example  chemistry, 
are  founded  are  so  obscured  by  the  conditions  in  which  they  occur 
that  special  devices  must  be  adopted  before  they  can  be  observed. 
No  one  will  maintain  formally  that  this  difference  in  the  way  in 


DESCRIPTION  AND  INTERPRETATION  503 

which  facts  are  gathered  ought  to  make  a  difference  in  the  kind  of 
thinking  by  means  of  which  they  are  welded  into  sciences.  There 
is,  however,  a  difference  between  sciences  which  is  more  important 
in  that  to  it  is  due  a  vast  difference  in  the  thinking  by  which  they 
are  created.  Some  sciences  are  founded  on  a  multitude  of  facts, 
and  some  on  a  very  few.  The  mathematical  sciences  are  examples 
of  the  latter  class.  Thus,  "  All  the  inductions  involved  in  all 
geometry  are  comprised  in  those  simple  ones,  the  formulae  of 
which  are  the  Axioms,  and  a  few  of  the  so-called  Definitions. 
The  remainder  of  the  science  is  made  up  of  the  processes  em- 
ployed for  bringing  unforeseen  cases  within  these  inductions  ;  or 
(in  syllogistic  language)  for  proving  the  minors  necessary  to 
complete  the  syllogisms ;  the  majors  being  the  definitions  and 
the  axioms.  In  those  definitions  and  axioms  are  laid  down  the 
whole  of  the  marks,  by  an  artful  combination  of  which  it  has  been 
found  possible  to  discover  and  prove  all  that  is  proved  in  geometry. 
The  marks  being  so  few,  and  the  inductions  which  furnish  them 
being  so  obvious  and  familiar;  the  connecting  of  several  of  them 
together,  which  constitutes  Deductions  or  Trains  of  Reasoning, 
forms  the  whole  difficulty  of  the  science,  and,  with  a  trifling  excep- 
tion, its  whole  bulk;  and  hence  Geometry  is  a  Deductive  Science."1 
The  definitions  are  precise  descriptions.  The  axioms  are  laws. 
We  have  defined  a  law  as  a  description  of  a  uniformity  in  the 
sequence  of  phenomena,  and  we  saw  that  it  is  usually  possible 
to  deduce  necessary  consequences  from  it  about  sequences  of 
phenomena, 

820.  Physics  in  all  its  branches  and  throughout  its  whole  vast 
extent  is  another  science  that  has  been  developed  from  a  few 
essential  facts  which  have  been  welded  into  laws  from  which  the 
rest  of  the  science  has  been  deduced.     Relatively  speaking,  very 
little  mere  recollection  is  needed  by  the  mathematician  or  the 
physicist.      His  *  knowledge,'   however   toilsomely  acquired,   con- 
sists mainly  in  a  special  skill  in  thinking  about  sequences. 

821.  Astronomy  is  a  science  which  is  founded  on  an  immense 
number  of  facts.     Thus  there  are  millions  of  stars,  only  a  few  of 
which  the  astronomer  has  named  and  attempts  to  recollect.     If 
he  merely  classified  his  facts  according  to  co-existences  and  re- 
semblances, for  example  if  he  classified  the  heavenly  bodies  accord- 
ing to  their  apparent  magnitudes,  luminosities,  and  positions  relative 
to  one  another,  astronomy  would  be  a  very  incomplete  science,  and 
the  best  astronomer  would  be  a  powerful  photographic  camera. 

1  J.  S.  Mill,  Logic,  ii.  iv.  4. 


504  EDUCATION 

But  every  astronomer  is  also  a  mathematician  and  physicist,  and  it 
is  the  application  of  mathematical  and  physical  laws  to  astronomy 
that  has  given  to  this  science  all  its  intellectual  splendour — that 
has  converted  the  astrologer  into  the  astronomer,  that  has  linked 
together  the  facts  of  astronomy  in  chains  of  causation,  that 
has  made  it  in  great  measure  a  deductive  science  founded  on 
laws. 

822.  Chemistry  is  based  on  an  enormous  number  of  facts,  but, 
as  far  as  I  am  aware,  has  only  one  law  of  considerable  importance, 
Dalton's  Atomic  Theory,  which  is  usually  regarded  by  chemists 
as  their  most  valuable  possession. 

823.  Systematic    zoology,    botany,   anatomy,    and    the    other 
systematic  sciences  that  relate  to  living  beings  are  also  founded 
on   a  great  number  of  facts,  probably   on    a  greater  number  of 
recorded  and  described  facts  than  any  of  the  other  sciences.     But 
they  have  no  laws.     They  are  descriptive  not  interpretative ;  their 
facts  are  classified  according  to  co-existences  and  resemblances, 
not  in   chains  of  causation.     In  effect,  they  consist  of  a  multi- 
tude of  definitions.     Thus  a  systematic  zoologist  will  tell  us  no 
more  about  a  man  than  that  he  possesses  certain  characters,  and 
that  therefore  he  is  an   animal    belonging   to   the   sub-kingdom 
Vertebrata,  class  Mammalia,  order  Bimana,  and  so  forth.      The 
faculties   required    by  the   young   learner   in    these   sciences   are 
mainly  observation  and  recollection.      No  doubt,  a  great  deal  of 
thought — comparison,  discrimination,  association,  and  the  like — 
is  needed  also ;    but,   as   compared    to   the   amount   required    in 
physics  and  mathematics,  it  is  very  small   in  proportion  to  the 
number  of  facts.     Moreover,  it  is  not  the  same  kind  of  thought — 
not  deductive,  not  interpretative  thought,  not  thought  about  the 
sequences  of  phenomena,  not  a  linking  together  of  facts  in  the 
relation  of  cause  and  effect,  not  a  process  of  inferring  the  pre- 
viously unknown  as  a  necessary  consequence  from  the  previously 
known,  not  ratiocination. 

824.  If  a  student  has  exceptional  powers  of  recollection  and 
observation  he  may  become  an   exceptionally  good   systematist. 
But  no  such  powers  by  themselves  will  enable  him  to  become 
a  great  mathematician  or  astronomer.      The  difference  between 
the  interpretative  and  descriptive  sciences  is  vividly  illustrated 
by  the  circumstance  that  I  am  able  in  a  short  time  to  ascertain 
all  that  I  want  to  know,  indeed  all  that  is  known  to  the  average 
systematist,  about  any  animal  or  plant,  by  turning  to  the  books 
on  my  shelves;  whereas  no  number  of  books  will  enable  me  to 


THE  SYSTEMATISTS  505 

understand  the  reasoning  of  the  mathematician  or  astronomer 
without  a  prolonged  preliminary  training  in  thinking.  The  mental 
attitudes  of  the  followers  of  the  two  kinds  of  sciences  are  markedly 
different.  Thus,  I  believe  every  student  of  the  interpretative 
sciences  would  regard  it  as  better  science  if  the  theory  that 
the  individual  recapitulates  the  life-history  of  the  race  were  first 
inferred  as  a  necessary  consequence  from  the  familiar  truth  that 
offspring  recapitulate  with  variations  the  development  of  their 
parents,  and  then  proved  by  an  appeal  to  the  less  familiar  facts 
of  embryology;  whereas  I  think  some  biologists  would  regard 
such  a  proceeding  as  unscientific,  and  would  prefer  to  begin  at 
the  other  end  and  found  an  untested  hypothesis  on  the  evidence 
furnished  by  embryology  alone.  Biology  is  remarkable  for  the 
number  of  untested  and  often  untestable  hypotheses  which  its 
followers  have  formulated.  Witness  the  numerous  hypotheses 
concerning  inheritance,  sex,  immunity,  and  cancer.  On  the  other 
hand,  if  a  physicist  formulates  a  hypothesis  he  is  almost  sure  to 
endeavour  to  furnish  not  only  the  evidence  on  which  it  is  founded, 
but  also  that  by  which  he  thinks  it  is  proved.  Witness  Kepler's 
rejection  of  nineteen  of  his  own  hypotheses,  which  he  disproved 
by  a  deductive  appeal  to  reality,  before  he  arrived  at  the  true 
statement  of  planetary  motion,  and  Newton's  suppression  for 
fifteen  years  of  a  true  theory  of  the  moon's  motion,  because  it 
did  not  accord  with  data  which  were  subsequently  found  to 
be  wrong.1 

825.  Obviously,  since  the  mathematician  has  only  a  few  data 
on  which  to  found  his  thinking,  his  science  must  be  deductive 
from  its  very  beginnings.     On  the  other  hand,  the  biologist,  like 
the  astronomer,  must  begin  by  classifying  his  facts  according  to 
co-existences  and  resemblances,  and  only  afterwards,  when  they 
have  thus  been  rendered  manageable,  proceed  to  construct  chains 
of  causation.     At  any  rate,  every  science,  the  facts  of  which  are 
very   numerous   and    which   has   passed    beyond    the   descriptive 
stage,  has  grown  in  this  way.2 

826.  Darwin  attempted  to  make  this  second  step.     In  his  theory 
of  Natural  Selection   he  formulated  that  which,  if  true,  is  a  real 
law.     He  described  a  uniformity  in  the  sequence  of  events  from 
which   necessary  consequences  could  be  deduced.     He  strove  to 
interpret  facts  about  living  beings,  and  so  to  link  them  together 
in  chains  of  causation.     Consciously  or  unconsciously  he  sought 
to  do  for  biology  what  Newton  had  already  done  for  physics  and 

1  See  §  72.  z  See  §  69  (footnote). 


506  EDUCATION 

astronomy.1  If  mathematics  and  physics  are  sciences,  his  work 
also  was  scientific,  for  he  formulated  a  hypothesis  which  was 
capable  of  being  tested.  But  this  arranging  of  facts  in  sequence 
was  a  kind  of  science  to  which  systematists,  as  such,  were 
not  accustomed,  and  which,  therefore,  some  of  them  put  aside 
austerely  as  that  which  was  not  science  but  *  speculation.' 
"  Parenthetically  we  may  notice  that  though  scientific  opinion  in 
general  became  rapidly  converted  to  the  doctrine  of  pure  selection, 
there  was  one  remarkable  exception.  Systematists,  for  the  most 
part,  kept  aloof.  Every  one  was  convinced  that  Natural  Selection, 
operating  in  a  continuously  varying  population,  was  a  sufficient 
account  of  the  origin  of  species,  except  the  one  class  of  scientific 
workers  whose  labours  familiarized  them  with  the  phenomenon  of 
specific  difference.  From  that  time  the  systematists  became,  as  they 
still  in  great  measure  remain,  a  class  apart.  A  separation  has  been 
effected  between  those  who  lead  theoretical  opinion  and  those  who  by 
taste  or  necessity  have  retained  an  acquaintance  with  the  facts.2  The 
consequences  of  that  separation  have  been  many  and  grievous.  To  it 
are  to  be  traced  the  extraordinary  misapprehensions  as  to  the  funda- 
mental phenomena  of  specific  difference  which  are  now  prevalent"  3 

1  "  We  claim  for  Darwin  that  he  is  the  Newton  of  natural  history,  and  that, 
just  so  surely  as  that  the  discovery  and  demonstration  by  Newton  of  the  law 
of  gravitation  established  order  in  place  of  chaos,  and  laid  a  sure  foundation  for 
all  future  study  of  the  starry  heavens,  so  surely  has  Darwin,  by  his  discovery  of 
the  law  of  natural  selection  and  his  demonstration  of  the  great  principle  of  the 
preservation  of  useful  variations  in  the  struggle  for  life,  not  only  thrown  a  flood 
of  light  on  the  process  of  development  of  the  whole  organic  world,  but  also  estab- 
lished a  firm  foundation  for  all  future  study  of  nature  "  (A.  R.  Wallace,  Darwinism, 
p.  9).     Nothing  in  the  histories  of  scientific  men  is  more  remarkable  than  Dr 
Wallace's  attitude.     No  one  would  suspect  from  his  own  writings  that  he  was 
Darwin's  co-discoverer  of  the  theory  of  natural  selection.     He  assigns  the  whole 
credit  to  the  elder  thinker.     I  imagine  that  posterity  will  be  more  just. 

2  Among   those  who   '  lead    theoretical  opinion,'  but  who,  to    judge    from 
Bateson's  language,  have  not  '  retained  an  acquaintance  with  the  facts,'  are 
Wallace,  Hooker,  Thiselton-Dyer,  Lankester,  Weismann,  Osborn,  and  Poulton. 

3  Bateson,  Mendel's  Principles  of  Heredity,  p.   3.     Bateson  continues,   "  If 
species  had  really  arisen  by  the  Natural  Selection  for  impalpable  differences, 
intermediate  forms  should  abound,  and  the  limits  between  species  should  be 
on  the  whole  indefinite.     As  this  conclusion  follows  necessarily  from  the  premises, 
the  selectionists  believe  and  declare  that  it  represents  the  facts  of  nature." 
Bateson  is  mistaken.     Selectionists  believe  that  evolution  has  resulted,  not  from 
the  selection  of  impalpable,  but  from  the  selection  of  fluctuating  differences. 
The  distinction  is  important.     Natural  selection  amongst  human  beings  is  the 
only  instance  of  this  process  observable  by  us,  and  the  reader  is  now  in  a  position 
to  judge  whether,  for  instance,  the  difference  between  a  man  who  perishes  of 
consumption  and  one  who  survives  in  the  same  environment  is  '  impalpable.'     If 
selection  amongst  men  were  such  that  short  and  weak  individuals  were  eliminated, 
while  tall  and  strong  individuals  survived,  if  men,  for  example,  fought  for  their 


BIOLOGICAL  TRAINING  507 

827.  The  question  arises  whether  the  attitude  of  those  syste- 
matists  who  have  'kept  aloof  from  speculation  can  be  justified. 
Here  speculation  means  nothing  other  than  an  attempt  to  link 
together  facts  concerning  animals  and  plants  in  chains  of  causation. 
Of  course,  speculation  may  be  what  even  students  of  other  sciences 
consider  illegitimate ;  that  is,  it  may  be  founded  on  data  which 
have  not  been  verified,  or  it  may  be  conducted  by  thinking  which 
is  not  tested.  But  no  such  considerations  seem  to  have  guided 
the  systematists  that  '  kept  aloof;  for,  as  their  aloofness  implies, 
they  did  not  attempt  to  impugn  either  the  facts  or  the  thinking, 
and  they  preserved  the  aloofness  even  after  the  actual  occurrence 
of  Natural  Selection  and  of  evolution  consequent  on  it  was 
demonstrated  amongst  men,  the  only  living  beings  with  whose 
lives  they  were  at  all  intimately  acquainted.  It  is  not  alleged  that 
their  attitude  was  due  to  lack  of  time,  or  of  interest,  or  of  knowledge 
of  the  facts.  Apparently  they  have  been  guided  by  the  more  or 
less  clearly  formulated  notion  that  science  is  created,  not  by  ascer- 
taining chains  of  causation,  but  solely  by  classifying  facts  according 
to  co-existences  and  resemblances.  Whether  they  are  right  or 
wrong  is,  in  the  absence  of  any  attempt  at  demonstration  by  them, 
a  matter  of  opinion  ;  but  it  is  worthy  of  notice  that  that  which  is 
condemned  by  them  is,  in  effect,  not  merely  the  science  of  Darwin, 
but  also  that  of  Bacon  and  Newton,  not  merely  the  theory  of 
Natural  Selection,  but  also  mathematics  in  its  entirety,  physics 
almost  in  its  entirety,  and  astronomy  in  the  best  part  of  its  extent. 
It  is  worthy  of  notice  also,  that  unless  human  beings  linked  together 
in  chains  of  causation  the  facts  they  learn  during  the  ordinary 
course  of  their  lives  they  would  not  be  rational  beings,  and  could 
not  maintain  existence.  The  circumstance  that  they  are  able 

mates,  the  differences  selected  would  not  be  impalpable.  It  is  true  that,  if  we 
arranged  all  the  members  of  a  variety  in  a  row  in  the  order  of  their  heights  or 
strengths  we  should,  as  a  rule,  find  the  differences  between  each  individual  and 
his  next  neighbours  very  small.  But  nature  would  do  nothing  of  the  kind.  On 
the  contrary,  she  would  simply  select  for  survival,  as  a  general  rule,  the  especially 
tall  and  strong,  and  for  elimination  the  especially  short  and  weak.  Forms  inter- 
mediate between  living  types  actually  abound  —  forms  that  are  intermediate 
between  one  kingdom  and  another,  one  class  and  another,  one  order  and  another, 
one  species  and  another,  or  one  variety  and  another.  No  selectionist  believes  that 
all  the  links  have  survived  or  are  known.  The  complete  chain  could  be  recon- 
structed only  if  every  generation  were  known  to  us.  Mutationists  do  not  doubt 
that  the  organic  world  has  arisen  by  evolution.  But  their  links  are  missing 
equally  with  those  of  the  selectionists  ;  for  none  will  maintain  that  the  vast  gaps 
which  exist  between  many  living  types  and  their  nearest  known  relations,  gaps 
which  involve  thousands  of  co-ordinated  changes,  can  ever  have  been  crossed  by 
a  single  leap. 


508  EDUCATION 

usefully  to  employ  this  mode  of  thinking  in  ordinary  life  is,  at 
least,  presumptive  evidence  that  it  can  be  usefully  employed 
in  science  where  especial  care  is  exercised. 

828.  My  object,  however,  is  not  to  assail  the  attitude  of  the 
systematists.      "  The  isolation   of  the  systematists  is  one  of  the 
most  melancholy  sequela  of  Darwinism." l     They  are  doomed  to 
extinction ;  for  facts  arranged  in  chains  of  causation  are  so  very 
much  more  interesting  to  normal  human  beings  than  facts  arranged 
in  any  other  way,  and  normal  people  are  so  driven  to  think,  are  so 
trained  to  think,  in  chains   of  causation,  by   the   ordinary   con- 
ditions of  their  lives,  that  even  the  severest  systematic  training 
can  hardly  repress,  and  rarely  quite  represses,  the  tendency,  the 
instinct,  to  think  in  that  way.     Pure  systematists  are  now  a  small 
minority,  even  among  biologists,  and  as  a  type  are  unknown,  and 
have   always  been  unknown,  amongst  the  students  of  all  other 
sciences.     The  great  weight  of  scientific  practice  and  opinion  has 
ever  been  strongly  against  them.     They  are  a  peculiar  product  of 
biological  training  which  still  remains  almost  purely  systematic ; 
for,  though  Darwin  greatly  altered  the  course  of  biological  thought, 
his  influence  has  not  yet  affected  the  method  by  which  students 
are  instructed  to  nearly  the  same  extent.     Like  monks  and  nuns, 
systematists  afford  a  remarkable  example  of  the  importance  of 
acquirement  in  human  mental  development,  and  of  its  power  to 
nullify  even  an  instinct. 

829.  My  object  is  to  draw  attention  to  the  circumstance  that, 
while  the  majority  of  biologists,  impelled  by  instinct  and  informal 
training,  think  about  biological  facts  in  terms  of  causation,  yet, 
unlike  mathematicians,  physicists,  and  astronomers,  they  receive 
little  or  no  formal  education  which  especially  fits  them  to  deal  with 
their  data  in  that  way.      Here  they  are,  in  fact,  untrained  thinkers. 
I   make  this  statement  with  no  offensive  intention.     It  may  be 
verified  in  any  centre  of  biological  teaching.     All  biological  cur- 
ricula  are   designed    to    impart    only   "  systematic "    knowledge. 
If  it  is  unscientific  to  think  in   terms  of  causation,  it  is   never 
explained  to  learners  why  it  is  unscientific.      The  result  is  that 
numbers  of  students  are  left  with  what  can  only  be  very  misty 
or  wrong  notions  as  to  what  constitutes  science.      The  circum- 
stance that  biologists  are  divided  by  real  sectarian  differences — 
that  is,  differences  founded  on  an  improper  acceptance  or  rejection 
of  evidence  or  modes  of  thinking  2 — is,  alone,  sufficient  proof  that 

1  Bateson,  Darwin  and  Modern  Science,  p.  89  (footnote). 
*  See  §  45- 


THE  RESULTS  OF  BIOLOGICAL  TEACHING         509 

their  training  is  defective.  Systematists  tacitly  repudiate  science 
which  is  created  by  linking  facts  in  chains  of  causation  ;  most 
scientific  men  regard  it  as  the  most  perfect  form  of  science. 
Experimentalists  seek  to  secure  accuracy  in  thinking  by,  in  effect, 
limiting  the  materials  of  thought  to  facts  furnished  by  experiment ; 
most  men  of  science  believe  that  one  of  the  essential  conditions  of 
accuracy  is  the  careful  taking  of  all  authentic  and  relevant  facts 
into  account.  Medical  men,  whose  professional  thinking  is  entirely 
in  terms  of  causation,  frequently  denounce  deduction  ;  most  men 
of  science  suppose  that  the  truth  of  hypotheses  can  be  tested  only 
by  means  of  it.  Even  biometricians,  who  are  mathematicians, 
rarely  test  their  thinking  deductively.  In  biology  they  follow  the 
prevailing  fashion,  using  mathematical  formulae,  but  not  mathe- 
matical methods  of  securing  accuracy  in  thinking.  The  science 
they  create  is  purely  empirical.  Judging  by  their  work,  they 
appear  to  suppose  that  thinking  which  is  founded  on  simple 
enumeration  and  which,  therefore,  is  isolated  and  untested,  is 
superior  to  thinking  which  is  founded  on  a  discovery  of  causes, 
and  which,  therefore,  is  linked  with  other  truth  and  can  be  tested 
by  it.  Most  scientific  men  believe  the  contrary. 

830.  Not  only  does  the  mathematician  always  endeavour  to 
test  his  thinking,  but  he  invariably  prefers  a  deductive  to  an 
enumerative  test.  Thus,  if  he  has  multiplied  one  number  by 
another,  he  has  a  greater  sense  of  certainty  that  he  has  thought 
correctly  when  he  has  divided  the  product  by  one  of  the  factors  and 
found  that  the  quotient  agrees  with  the  other  than  when  he  has 
repeated  his  multiplication  a  dozen  times.  In  the  former  case  he 
thinks  that  he  has  proved  the  correctness  of  his  thinking ;  in  the 
latter  he  supposes  that  he  has  merely  raised  an  expectation  that 
it  is  correct.  Yet,  since  the  conditions  of  thought  are  usually 
relatively  simple  in  the  mathematics,  it  is  here,  if  ever,  that  testing 
by  simple  enumeration  should  be  useful ;  for  the  simpler  the  con- 
ditions the  less  likely  it  is  that  any  essential  factor  has  been 
omitted  or  wrongly  thought  about,  or  that  any  non-essential  factor 
has  been  included.  On  the  other  hand,  the  conditions  are  usually 
very  complex  in  biology.  We  are  constantly  liable  to  confuse  the 
essential  with  the  non-essential.  Here,  if  ever,  simple  enumeration 
should  be  dangerous  and  deduction  comparatively  safe  and  useful. 
Nevertheless,  many  biologists,  though  professing  admiration  for 
the  mathematics  as  the  type  of  all  that  is  accurate,  express  or 
imply  the  utmost  contempt  for  testing  (i.e.  deduction)  when  used 
in  their  own  science.  Thus,  the  fact  that  long  lost  ancestral  traits 


5io  EDUCATION 

sometimes  appear  in  pure-bred  individuals  seems,  according  to  the 
mathematical  conception  of  science,  to  furnish  conclusive  proof 
that  the  Mendelian  doctrine  of  segregation  is  erroneous.  If, 
however,  we  mention  this  test  to  a  member  of  the  experimental 
school,  we  are  sure  to  find  that  it  carries  no  conviction.  He  will  not 
attempt  to  demonstrate  that  the  supposed  test  is  no  test.  He  will 
merely  declare  that  the  problems  of  heredity  are  not  to  be  solved 
in  the  arm-chair  by  essayists,  logicians,  or  dialecticians,  but  only 
by  real  men  of  science  labouring  in  the  laboratory  or  the 
breeding  pen.  If  we  insist  that  the  "dialectician"  is  utilizing 
all  the  experimental  facts  and  more  besides,  that  it  is  needful 
that  even  "real"  men  of  science  shall  test  their  thinking,  that 
thinking  can  be  carried  on  as  well  in  an  armchair  as  a  breeding 
pen,  and  that  the  experiments  on  which  he  relies  prove,  not 
alternative  inheritance,  but  only  alternative  reproduction,  he  will, 
by  way  of  retort,  adduce  similar  experiments  on  rabbits.  If 
we  raise  the  same  objections  to  these,  he  will  adduce  like 
experiments  on  fowls.  And  so  on,  and  so  on.  Ultimately  we 
are  left  to  wonder  helplessly  whether  he  is  unaware  of  the  true 
nature  of  science,  or  whether  every  one  who  has  both  thought  and 
expressed  himself  clearly  about  it  is  unaware ;  whether  biology, 
which,  from  the  scientific  standpoint  of  the  mathematician  and 
physicist,  seems  so  pregnant  with  great  possibilities,  so  laden  with 
tremendous  issues,  is  in  truth  so  mean  and  narrow  a  thing,  a 
mere  guessing  about  the  abnormalities  of  sexual  reproduction,  or 
at  most  no  more  than  a  study  of  the  function  of  sex ;  whether  a 
new  and  more  accurate  science  is  really  being  created  by  exclusive 
devotion  to  experiments  and  abnormalities,  or  whether  we  are 
spectators  in  a  kind  of  confidence  trick  in  which  a  display  of 
experiment  is  used  to  obtain  a  fictitious  appearance  of  accuracy. 

831.  Whoever  is  right  some  one  must  be  wrong ;  and  a  teach- 
ing which  results  in  such  a  babble  of  opinions  must  be  wrong  aiso. 
A  mathematician  will  seldom  affirm  contradictories,  and  any 
statement  by  him  is  usually  accepted  or  rejected  by  his  fellows 
on  grounds  of  pure  fact  and  reason.  The  same  is  true  of 
physicists,  chemists,  and  astronomers.  But  a  biologist — as  when 
he  upholds  both  the  theory  of  recapitulation  and  the  Law  of 
Ancestral  Inheritance,  both  the  theory  of  Natural  Selection  and 
the  notion  that  variations  are  caused  by  the  direct  action  of  the 
environment,  both  the  hypothesis  that  harmful  conditions  cause 
races  to  decline  and  the  hypothesis  that  such  conditions  cause 
races  to  progress  in  the  same  characters  at  the  same  time — often 


SUMMARY  511 

displays  a  power  of  affirming  contradictories  which  is  not  exceeded 
by,  and  is  much  less  excusable  than  that  displayed  by  the 
adherents  of  any  of  the  creeds.  The  latter  do  not  profess  to  be 
guided  solely  by  verified  truth  and  pure  reason.  Moreover,  in 
many  instances  the  statements  of  the  biologist  are  judged  on 
grounds  of  pure  prejudice  by  many  of  his  fellows. 

832.  Biologists  often  insist  that  'the  time  has  come'  when  the 
traditional  education  of  young  adults  shall  be  replaced  by  a  training 
in  science.    But  of  all  modern  sciences  the  most  fundamentally  im- 
portant is  the  science  of  education  ;  and  the  training  accorded  to 
young  biological  students  is  precisely  that  kind  which  is  most  con- 
demned by  modern  educationalists  who  denounce,  for  example,  tradi- 
tional, classical,  historical,  and  geographical  teaching  as  consisting 
too  much  in  a  mere  learning  and  comparison  of  words,  dates,  lengths 
of  rivers,  and  the  like.     They  insist  that  it  is  not  enough  to  store 
the  memory  with  facts ;  intelligence  must  also  be  developed  ;  and  by 
intelligence  they  always  mean  skill  in  thinking  in  terms  of  causation. 

833.  Systematic  knowledge  is  necessary  to  biologists,  but,  to 
judge  by  what  the  students  of  other  sciences  consider  essential, 
it  is  not  all  that  is  necessary.     If  it  be  right  that  scientific  men 
shall   have   their    powers    of   precise    thinking    about    sequences 
developed  to  the  utmost  by  formal  training ;  if  the  most  complete 
science  is  created  not  merely  by  classifying  facts  according  to  their 
co-existences  and  resmblances,  but  also  by  classifying  them  accord- 
ing to  their  causal  relations  ;  if  the  former  method  of  classification 
is  the  warp  and  the  latter  the  woof  of  perfected  science ;  if  facts 
should  be  arranged  not  only  according  to  one  relation,  but  accord- 
ing to  every  relation  ; — then  there  ought  to  be  a  considerable  change 
in  biological  education,  and  learners  should  receive  a  formal  training 
in  the  method  of  classification  which  Darwin  has  done  so  much  to 
introduce  as  well  as  in  the  method  of  which  Linnaeus  was  so  great 
an  exponent. 

834.  It  is  not  merely  the  education  of  biologists  that  is  in  question. 
All  education  is  in  question.    And  very  much  more  than  education  ; 
for  on  its  mental  training  depends  almost  absolutely,  both  in  war 
and  in  peace,  the  weal  and  woe  of  every  human  race.     Whoever 
has  attempted  to  bring  about  any  sort  of  reform — from  that  of  a 
slaughter-house  to  that  of  a  state,  from  that  of  a  nursery  to  that 
of  a  religion — knows   well   that   his  chief  difficulties   lie,  not  in 
the   ignorance   of  those   he  would    influence,   for  facts   however 
laboriously  gathered   are  readily  imparted,  but  rather   in  mental 
states  engendered  by  an  education  which  does  little  to  create  a 


512  EDUCATION 

habit  of  open-mindedness  to  new  ideas.  Only  biologists  are  in  a 
position  to  know  the  fundamental  facts — to  ascertain  what  is 
"  inborn "  and  what  "  acquired "  in  the  human  mind,  and  to 
discover  how  any  desired  quality  may  best  be  evolved  or 
developed,  and  any  defect  eliminated.  When  we  think  about 
what  is  good  or  bad  in  education,  we  think  in  terms  of  causation. 
Not  until  biologists  have  trained  their  students  by  direct  methods 
to  become  skilful  in  the  interpretation  of  evidence,  and  thus  have 
raised  a  body  of  workers  capable  of  becoming  effective  thinkers 
about  education,  not  until  their  science  teaching  has  become 
scientific  in  method,  will  they  be  in  a  postion  to  speak  with  the 
authority  that  is  their  right.  And  not  until  then  will  the  mental 
training  of  the  general  public  receive  a  reform  of  which  there 
is  urgent  need,  and  the  practical  utility  and  intellectual  splendour 
of  biology  be  recognized  by  all  men. 

835.  In  this  book,  now  finished,  I  have  tried,  however  un- 
successfully, to  follow  the  only  method  by  which  all  thinkers 
who  have  expressed  themselves  on  the  subject  have  supposed  it 
possible  to  trace  sequences  of  cause  and  effect  with  any  degree 
of  certainty — the  method  of  using  some  (as  many  as  possible) 
of  the  available,  authentic,  and  relevant  facts  for  the  foundations 
of  hypotheses,  and  the  remainder  (which  of  necessity  are  usually 
by  far  the  greater  number)  to  test  the  correctness  of  the  thinking 
— the  method  of  fitting  each  inference  to  all  the  facts, -no  matter 
how  numerous  or  how  gathered,  and  so  of  never  resting  content 
until  every  devisable  test  had  been  satisfied.  "An  hypothesis 
is  any  supposition  which  we  make  (either  without  evidence,  or  on 
evidence  avowedly  insufficient)  in  order  to  endeavour  to  deduce  from 
it  conclusions  in  accordance  with  facts  which  are  known  to  be  eal ; 
under  the  idea  that  if  the  conclusions  to  which  the  hypoth  sis 
leads  are  known  truths,  the  hypothesis  itself  must  be,  or  at  least 
is  likely  to  be,  true."  l  The  reader  has  perhaps  noted  that,  while  I 
have  rarely,  if  ever,  contradicted  alleged  facts,  many  of  which  in 
common  with  all  other  people  I  have  been  obliged  to  accept  at 
second  hand  on  what  appeared  good  authority,  I  have  often  con- 
troverted inferences,  none  of  which  we  are  obliged  to  accept  at 
second  hand,  which  seemed  to  me,  when  tested,  to  conflict  with 
well-known  and  undisputed  truths.  "  An  opinion  which  stands  in 
need  of  much  illustration  can  often  receive  it  most  effectually, 
and  least  tediously,  in  the  form  of  a  defence  against  objections. 
And  on  subjects  concerning  which  speculative  minds  are  still 
1  J.  S.  Mill,  Logic,  iii.  xiv.  4. 


SUMMARY  513 

divided,  a  writer  does  but  half  his  duty  by  stating  his  doctrine, 
if  he  does  not  also  examine,  and  to  the  best  of  his  ability  judge, 
those  of  other  thinkers."1  However  completely  I  may  have 
failed  in  all  else,  I  am  not  without  hope  that  I  have  demonstrated 
at  least  that  much  evidence,  hitherto  neglected,  particularly  that 
furnished  by  human  diseases,  is,  if  used  in  accordance  with  the 
methods  employed  in  the  other  sciences,  valuable  to  the  student 
of  heredity  and  evolution  in  his  strivings  to  create  a  coherent 
body  of  thought  and  knowledge,  the  various  parts  of  which  shall 
interlock  as  smoothly  and  consistently  as  those  of  any  other 
deductive  science. 

836.  We  have  journeyed  in  a  wide  and  in  parts  untravelled 
region  of  thought,   and  have  ambitiously  endeavoured  to   solve 
the  greater  problems  of  heredity.      If  in  any  instance  we  have 
succeeded,  then  in  each  such  case  a  law  of  nature  has  been  formu- 
lated which,  as  far  as  I  am  able  to  judge,  is  as  nearly  fundamental 
as  can  be  discovered  in  the  present  state  of  our  knowledge.     Of 
these  laws,  if  any  of  them  are  real  laws,  the  most  important  from 
the  scientific  standpoint,  because  the  most  basic,  is  the  generaliza- 
tion that  the  vast  majority  of  variations  are  under  the  immediate 
control  of  natural  selection,  and  therefore  are  spontaneous  in  the 
sense  that  they  arise  independently  of  the  direct  action  of  the 
environment,   and  that  on  these  spontaneous  variations  only  is 
evolution  built ;  for  they  only  are  products  of  the  normal  growth 
and  change  of  the  germ-plasm,  all  others  being  results  of  injury 
to  it.     If  this  be  a  truth,  the  close  and  continuous  adaptation  of 
persisting  species  to  their  environments  necessarily  follows.     On 
the  other  hand,  the  conclusion  that  the  "  acquirements "  of  the 
individual  are  as  much  a  part  of  his  inheritance  as  his  "  inborn  " 
traits  is,  from  the  practical  standpoint,  the  most  important  of  all. 
If  this  be  a  truth,  we  have  a  valid  explanation 'of  the  principal 
line  of  evolution  of  the  higher  animals,  and  a  potent  means  of 
influencing  our  own  species  for  good  and  evil. 

837.  The  matters  we  have  dealt  with  have  been  complex  and 
difficult,  and  I  fear  it  is  more  than  probable  that  the  reader  has 
detected  numerous  errors  and  inadequacies  of  fact  and  reasoning. 
For   them    I    ask   no   sort  of  indulgence — more   especially  as    I 
have   often  challenged   him   to   indicate   material   misstatements 
and  omissions,  or,  given  the  facts  as  true  and  comprehensive,  to 
indicate  how  any  conclusions  other  than  those  reached  are  con- 
ceivable.     But  I  have  the  right  to  claim,  either  that  I  shall  be 

1  Op.  cit.,  ii.  vii.  i. 
33 


514  EDUCATION 

judged  accordingly  as  I  have,  or  have  not,  followed  the  established 
rules  under  which  all  science  has  been  created  hitherto,  or  that 
the  reader  shall  plainly  think  out  his  reasons  for  rejecting  them. 
Conceivably  these  established  rules  are  wrong.  But  in  that  case 
they  should  be  shown  to  be  wrong.  To  imply,  as  is  so  often  done, 
that  they  are  wrong  merely  by  setting  up  private,  unexplained, 
and  apparently  indefensible  standards  for  evidence  and  proof  is  to 
destroy  the  distinction  between  scientific  and  sectarian  thinking — 
is  to  render  scientific  discussion  as  futile  and  scientific  dissension 
as  unappeasable  as  the  discussions  and  dissensions  of  religious 
factions. 

838.  "  Principles  of  Evidence  and  Theories  of  Method  are  not 
to  be  constructed  a  priori.  The  laws  of  our  rational  faculty,  like 
those  of  every  other  natural  agency,  are  only  learnt  by  seeing 
the  agent  at  work.  The  earlier  achievements  of  science  were  made 
without  the  conscious  observance  of  any  Scientific  Method ;  and 
we  should  never  have  known  by  what  process  truth  is  to  be 
ascertained  if  we  had  not  previously  ascertained  many  truths. 
But  it  was  only  the  easier  problems  that  could  be  thus  resolved  : 
natural  sagacity,  when  it  tried  its  strength  against  the  more  difficult 
ones,  either  failed  altogether,  or  if  it  succeeded  here  and  there  in 
obtaining  a  solution,  had  no  sure  means  of  convincing  others  that 
its  solution  was  correct.  In  scientific  investigation,  as  in  all  other 
works  of  human  skill,  the  way  of  obtaining  the  end  is  seen,  as  it 
were,  instinctively  by  superior  minds  in  some  comparatively  simple 
case,  and  is  then,  by  judicious  generalization,  adapted  to  the 
variety  of  complex  cases.  We  learn  to  do  a  thing  in  difficult 
circumstances  by  attending  to  the  manner  in  which  we  have 
spontaneously  done  the  same  thing  in  easier  ones. 

839.  "  This  truth  is  exemplified  by  the  history  of  the  various 
branches  of  knowledge  which  have  successively,  in  the  ascending 
order  of  their  complication,  assumed  the  character  of  sciences  ;  and 
will  doubtless  receive  fresh  confirmation  from  those  of  which  the  final 
scientific  constitution  is  yet  to  come,  and  which  are  still  abandoned 
to  the  uncertainties  of  vague  and  popular  discussion.  Although 
several  other  sciences  have  emerged  from  this  state  at  a  compara- 
tively recent  date,  none  now  remain  in  it  except  those  which  relate 
to  man  himself,  the  most  complex  and  most  difficult  subject  of 
study  on  which  the  human  mind  can  be  engaged.1  .  .  . 

1  Mill  was  mistaken.  He  was  thinking  of  the  study  of  human  mind  and  society 
in  terms  of  causation.  But  already  Darwin  had  published  his  view  of  the  origin 
of  species,  and  Wallace  his  famous  companion  essay.  Stimulated  by  them. 


SCIENTIFIC   METHOD  515 

840.  "  If,  on  matters  so  much  the  most  important  with  which 
the  human  intellect  can  occupy  itself,  a  more  general  agreement 
is  ever  to  exist  among  thinkers  ;   if  what  has  been  pronounced 
( the  proper  study  of  mankind  '  is  not  destined  to  remain  the  only 
subject  which  Philosophy  cannot  succeed  in  rescuing  from  Empiri- 
cism ;   the  same  process  through  which  the  laws  of  many  simpler 
phenomena  have  by  general  acknowledgment  been  placed  beyond 
dispute   must   be   consciously  and    deliberately   applied  to  those 
more  difficult  inquiries.     If  there  are  some  subjects  on  which  the 
results  obtained  have  finally  received  the  unanimous  assent  of  all 
that  have  attended  to  the  proof,  and  others  on  which  mankind 
have  not  yet  been  equally  successful ;  on  which  the  most  sagacious 
minds  have  occupied  themselves  from  the  earliest  date,  and  have 
never  succeeded  in  establishing  any  considerable  body  of  truths, 
so  as  to  be  beyond   denial  or  doubt ;    it  is  by  generalizing  the 
methods  successfully  followed  in  the  former  inquiries,  and  adapting 
them  to  the  latter,  that  we  may  hope  to  remove  this  blot  on  the 
face  of  science."  1 

841.  To  sum  up:  whether  we  consider  the  histories  of  indi- 
viduals, or  peoples,  or  sciences,  or  religions,  or  peace,  or  war,  or 
education,   or   commerce,   or  invention,   or  legislation,  indeed  of 
almost  any  field  of  human  endeavour,  one  truth  is  seen  to  stand 
forth  vividly  and  unmistakably  the  moment  our  attention  is  drawn 
to  it — the  truth  that  human  progress  and  success  depend,  and  have 
ever  depended,  chiefly  on  a  power  acquired  through  antecedent 
training,  a   habit,   of  thinking  skilfully   about   causes   and   their 
effects.     Thus  only  have  men,  by  studying  the  present,  been  able 
with  any  degree  of  certainty,  to  realize  the  past  and  anticipate' 
the   future.      This  kind   of  thinking   is   skilful   only  when   it   is 
carefully  tested    and   comprehensive.      Beginning   with   general- 
izations   from    experience,    it    proceeds,    therefore,    to    establish 
these  generalizations  and  extend    the  area  covered  by  them  by 
a  thorough  and  relentless  appeal  to  reality.       Only  those  indi- 
viduals have  achieved  enduring  success  that  have  thought  in  this 
way.     Only  those  nations  have  been  great  and  progressive  that 

many  other  men  besides  were  at  work  to  discover  the  causal  relations  that  link 
together  the  different  kinds  of  plants  and  animals  that  have  appeared  on  earth. 
As  we  have  seen,  all  Mill  wrote  was  then,  and  is  now,  strictly  applicable  to  the 
whole  study  of  causation  in  relation  to  living  beings — that  is,  to  the  whole  study 
of  heredity  and  evolution,  and  all  that  it  implies.  To  this  day,  because  of  funda- 
mental differences  concerning  evidence  and  method,  biological  thinkers,  however 
right  they  may  be,  can,  as  a  rule,  convince  only  minorities  of  their  fellows. 
1  Op.  cit.,  vi.  i.  i. 


516  EDUCATION 

have  trained  their  youth  to  think  in  it.  Only  those  religions  that 
have  not  greatly  obstructed  this  method  of  reaching  truth  have 
been  associated  with  growing  civilizations.  Only  those  sciences 
have  become  interpretative  in  which  it  has  been  systematically 
recognized  and  followed.  The  races  that  have  been  barbarous,  the 
religions  that  have  caused  stagnation  and  disorder,  the  systems  of 
education  that  have  been  futile,  the  sciences  that  have  been  cock- 
pits of  factions  and  tumbling  grounds  of  whimsies,  the  armies  that 
have  been  defeated  in  war,  the  individuals  that  have  laboured  in 
vain — these  have  all  owed  their  misfortunes  to  lack  of  thorough- 
ness in  thinking ;  that  is,  to  an  insufficient  testing  of  suppositions, 
and,  therefore,  to  an  incomplete  survey  of  the  facts. 


APPENDIX 

AN  ATTEMPT  TO  REPRESENT  DIAGRAMMATICALLY  SOME  OF 
THE  IDEAS  CONNECTED  WITH  INHERITANCE 

BY 

HERBERT  HALL  TURNER,  D.Sc.,  LL.D.,  F.R.S. 

Savilian  Professor  of  Astronomy,  Oxford 

i.  ^NTRODUCTORY.— The  perusal  of  Dr  Archdall  Reid's  Prin- 
f  ciples  of  Heredity,  and  of  the  present  work,  suggest  that  there  is  a 
-^-  closer  resemblance  between  biological  and  geometrical  reasoning 
than  might  be  supposed.  Starting  from  certain  axioms  in  geo- 
metry, a  considerable  superstructure  is  erected  by  following  necessary  laws 
of  thought.  In  biology,  there  are  no  axioms  of  the  same  kind  ;  but  there 
are  some  fundamental  truths  which  may  to  some  extent  take  their  place ; 
as,  for  instance,  that  children  resemble  their  parents.  The  precision  of  an 
axiom  is  absent :  so  is  the  self-evidence  :  but  the  universality  of  the  truth 
and  its  universal  acceptance,  when  once  the  limits  of  application  are 
understood,  are  comparable  with  those  of  a  geometrical  axiom.  Every 
one  knows  that  the  offspring  of  an  elephant  will  be  an  elephant,  of  a  dog 
a  dog,  of  a  butterfly  a  butterfly  similarly  marked.  The  resemblance 
between  parent  and  child  only  extends  to  broad  features  and  breaks  down 
at  details,  and  hence  the  necessity  for  specifying  limits  of  application. 
But  there  is  no  difficulty  about  this  unless  we  try  to  be  too  precise.  We 
know  with  equal  confidence  that  children  differ  from  their  parents ; 
i.e.  that  no  two  beings  are  ever  precisely  alike ;  each  of  these  two  appar- 
ently contradictory  propositions  is  undeniably  true  within  its  own  limits 
of  application :  and  though  these  limits  cannot  be  precisely  defined,  they 
are  well  understood. 

2.  Now,  Dr  Archdall  Reid  has  shown  that  we  may  build  upon  such 
truths    as    these    in   a    manner   not  very  different   from  that  in   which 
geometers  build  upon  their  fundamental  truths.    For  instance,  he  deduces 
Recapitulation  from  the  two  principles  just  quoted,  and  little  more;  he 
insists  that  we  need  not  have  derived  it  from  independent  observation, 
but  could  have  deduced  it  (as  a  necessity  of  thought)  from  other  principles 
already  known  and  more  familiar. 

3.  To  a  mathematician  such  a  view  is  fascinating,  and  his  impulse  is 
immediately  to  seek  mathematical  analogies  or  diagrammatic  representa- 
tions, which  help  him  to  picture  the  process  of  thought.     Thus,  he  may 
think  of  the  resemblance  between  the  growth  of  a  child  and  that  of  its 
parent  as  represented  by  two  similar  tracks — let  us  say  the  tracks  of  the 
front  and  hind  wheel  of  a  bicycle.     They  are  nearly,  but  not  quite,  the 
same.     If  a  third,  fourth,  fifth  wheel  followed  in  similar  sequence,  we 

517 


5i8 


APPENDIX 


should  have  a  representation  of  ancestry  by  the  successive  tracks  which 
would  appeal  specially  to  a  mathematician,  who  is  accustomed  to  curves  and 
their  properties.  Given  this  tendency  of  one  wheel,  or  say  of  one  cyclist, 
to  follow  the  preceding,  it  is  suggested  at  once  that  the  general  path  will 
remain  much  the  same  unless  there  is  some  persistent  disturbing  cause — 
say  the  gradual  wearing  away  of  a  bad  patch  on  the  road.  Further,  it 
is  possible  that  each  cyclist,  though  following  the  path  of  his  predecessor, 
may  ride  just  a  little  quicker  and  farther ;  so  that  what  was  once  the 
whole  extent  of  the  ride  becomes  ultimately  only  an  early  stage  of  it  passed 
over  with  great  rapidity  :  and  we  thus  arrive  very  simply  at  a  conception 
nearly  related  to  that  of  Recapitulation  in  biology. 

4.  Nothing  is  proved  by  this :  but  when  Dr  Archdall  Reid  challenges 
his  readers  to  think  of  any  possible  alternative  to  Recapitulation,  such 
analogies  help  the  mathematician  by  presenting  the  corresponding  diffi- 
culty of  travelling  from  one  point  to  another  without  passing  through 
intermediate  positions.     One  may  "  go  round,"  but  this  is  to  lose  time  : 
and  for  living  beings,  natural  selection  makes  it  important  to  save  time — 
to  reach  strength  and  maturity  early.    The  cyclist  we  have  pictured  above 
can  save  time  in  two  ways  only :  by  going  quicker  or  by  shortening  the 
route.     If  their  predecessors   had  laid  down  a  circuitous  route,   those 
following   later    may   shorten    it    by    "  cutting   across " :    but   we    must 
remember  that  time  was  important  for  the  predecessors  also,  since  they 
too  were  naturally  selected :  and  hence  they  were  forced  into  the  most 
direct  route  they  could  find.     The  path   is   thus  constantly  tending  to 
become  straight,  and  to  be  ridden  quicker. 

5.  This  illustration  will  serve  to  show  the  kind  of  temptation  which 
besets  a  reader,  whose  training  has  been  mathematical,  to  think  in  his 
own  terms ;  and  to  feel  that  ideas  are  clearer,  to  him  at  any  rate,  when 
expressed  in  those  terms.     It  will  thus  explain  the  origin  of  the  following 
essay  in    diagrammatic    representation  of  biological    conceptions.     The 
crudity  and  imperfections  of  the  attempt  are  too  obvious  to  be  covered 
by  any  apology:    but  they  may  stimulate  some  abler  pen  to  a   more 
successful  endeavour. 

6.  Diagrammatic  representation. — Let  the  size  of  an  organ  or  feature 

(length  of  arm,  weight  of  brain, 
etc.)  or  its  degree  (clearness 
of  vision  measured  in  some 

—  selected  manner)  be  repre- 
sented in  the  familiar  way  by  a 

->  diagram,  in  which  one  ordinate 
is  the  time  scale  measured 
along  OX  in  any  convenient 
units,  i,  2,  3,  4,  5,  etc.,  which 

-£  may  be  years  for  a  man,  or 
days  for  an  insect;  the  other 
axis,  OY,  being  devoted  to  the 
size  or  degree  of  the  organ.  Then  the  growth  of  the  organ  will  be 
represented  by  a  path,  ORPQS,  of  some  kind,  which  has  the  follow- 


Time.  ScaJe, 
FIG.  i, 


GENERAL  FEATURES  OF  GROWTH 


519 


FIG.  2. 


ing  properties  :  (a)  It  starts  from  O,  since  all  organs  must  have  a  beginning. 
(b)  It  ends  at  some  point,  T,  when  the  animal  dies,  (c)  The  ordinates, 
RL,  PM,  QN,  SV,  etc.,  tend  generally 
to  increase.  There  is  nothing  im- 
possible in  a  decrease  such  as  PQ 
(Fig.  2),  much  less  in  a  stationary 
period  such  as  PR  in  Fig.  2  ;  but  the 
general  rule  in  Nature  is  growth,  and 
for  the  present  the  exceptions  may  be 
left  out  of  consideration. 

7.  Resemblance  to  parents. — Now 
let  the  path  for  a  certain  organ  in  a 
parent  be  OQP,  PD  being  the  size  at 
a  time  OD  selected  for  observation  or 
measurement.  At  a  corresponding  time 
in  the  life  of  one  of  the  offspring  let 
the  corresponding  organ  be  observed  or 
measured,  and  found  to  be  pD.  Then 
we  know  from  experience  that — chil- 
dren resemble  their  parents  —  (I.), 
and  hence  that  pD  will  not  be  very 
different  from  PD  on  the  average.  But 
also  we  know  that — children  are  not 
exactly  like  their  parents,  and  may 
differ  from  them  either  way  —  (II.), 


FIG.  3. 


and  hence  pD  will  usually  differ  from  PD  ;  and  the  difference  may  be  in 
either  direction. 

8.  But  the  two  elementary  principles  just  stated  tell  us  more  than 
this.  The  resemblance  and  the  difference  are  not  applicable  to  a  single 
moment  only  such  as  OD ;  they  extend  throughout  life,  and  consequently 
if  we  observe  the  corresponding  organs  at  any  previous  time  Od,  we  shall 
find  that  dq  is  not  very  different  from  dQ,  though,  as  a  rule,  not  exactly 
equal  to  it. 

It  is  easily  seen  that  the  path  Oqp  for  the  child  will  thus  lie  near  to 

that  OQP  for  the  parent  throughout 
its  whole  length ;  or  in  other  words — 
the  development  of  the  child  is  a 
recapitulation  of  the  parental  develop- 
ment—CHI.). 

9.  The  tendency  to  diverge. — Let 
us  now  suppose  that  the  path  OA  is 
followed  by  a  certain  individual.  (For 
convenience  it  and  other  paths  are 
drawn  straight,  but  this  in  no  way 
affects  the  argument  at  present.)  His 
children  may,  and  generally  will, 
follow  paths  near  this,  such  as  OB  and  Ob,  which  may  differ  from 
OA  in  opposite  directions.  The  children  of  OB  will  similarly,  in 


X 


FIG.  4. 


520  APPENDIX 

general,  follow  either  a  path  Oc,  which  is  a  return  towards  the 
ancestral  path  OA,  and  may  even  go  on  the  other  side  of  it,  or 
a  path  OC,  which  is  a  further  deviation  from  the  ancestral.  We  are 
not  yet  in  a  position  to  say  anything  of  the  relative  chances  of  these 
two  possibilities,  but  experience  of  a  wide  kind  tells  us  that  both  are 
possibilities ;  and  similarly  it  is  possible  for  the  children  OD,  Od  of  Ob 
either  to  return  towards  the  ancestral  type  (as  OD)  or  to  diverge  further 
from  it  as  Od.  Hence  there  is  a  continual  tendency  to  produce  descen- 
dants differing  more  and  more  from  the  original  type  in  both  directions, 
and  if  this  tendency  were  unchecked  we  should  get  animals  of  all  sorts 
of  miscellaneous  shapes.  There  are,  however,  three  important  checks  to 
this  tendency  which  may  not  be  entirely  independent,  but  which  we  will 
consider  separately  in  the  first  instance;  they  are  (a)  the  sexual,  (fr) 
the  ancestral,  (c)  the  retrogressive.  The  first  two  we  can  deal  with  at 
once :  the  third  is  more  conveniently  deferred  until  we  come  to  natural 
selection  (§  55). 

10.  Influence  of  Two  Sexes. — Most  living  forms  are  the  children  not 
of  one  individual  but  of  two.     Let  the  path  of  one  parent  be  OQ,  and 

of  the  other  OS.  What  will  be  the  path 
of  the  child?  We  know  from  wide  ex- 
perience that — as  a  rule  children  resemble 
both  parents — (IV.),  and  thus  the  child's 
path  will,  as  a  rule,  be  intermediate  between 
the  paths  OQ  and  OS;  not  necessarily 
half-way  between  them,  but  somewhere 
intermediate.  The  child's  path  may  be 
such  as  OC  nearer  to  OQ,  or  OD  nearer 
— ^  to  OS.  There  might,  for  instance,  be  a 
tendency  for  the  child  to  resemble  the 
father  rather  than  the  mother ;  and  if  OQ 

be  the  path  of  the  father,  the  child's  path  would  be  like  OC.  But  if 
for  every  pair  of  parents,  OQ  OS,  in  which  OQ  represents  the  father  there 
exists  another  pair  in  which  OQ  represents  the  mother  (V.),  then  for  every 
child  OC  above  the  half-way  path  we  shall  have  another  child  OD  equally 
below  the  half-way  path,  and  on  the  average  the  children  will  follow  the 
half-way  path. 

11.  The  condition  italicized  is  roughly  in  accordance  with  experience. 
There  are  tall  men  with  short  wives  and  short    men   with  tall   wives. 
Whether  there  are  more  of  the  former  than  the  latter  we  cannot  say 
without   statistical    inquiry:    but    it  is    easily    seen    that  the   condition 
must  be  roughly  fulfilled.     For  take  any  ten  married  couples  :    divide 
the  men  into  tall  and  short — five  of  each :  the  women  also  into  tall  and 
short — five  of  each.   Suppose  three  tall  men  marry  tall  women  :  then  two 
tall  men  marry  short  women.     There  are  thus  left  five  short  men  married 
to  three  short  and  two  tall  women. 

12.  The  argument  is  quite  general.     If  we  take  n  tall  men  and  n 
short  men :  n  tall  women  and  n  short  women  :  and  if  x  of  the  tall  men 
have  tall  wives  :  then  n  -  x  have  short  wives.    And  since  x  tall  women  are 


EFFECT  OF  SEX  ON  TYPE  521 

already  disposed  of,  the  remaining  n  -  x  tall  women  must  have  short 
husbands,  just  as  many  as  there  are  tall  men  with  short  wives.  Hence 
the  generality  of  the  proposition  is  only  limited  by  two  assumptions 
tacitly  made,  viz.  : — 

1 i )  That  there  are  equal  numbers  of  tall  and  short.     We  can  always 
secure  this  by  arranging  the  individuals  in  series  and  counting  to  the 
half-way.     But  the  separation  will  in  general  be  rather  arbitrary  since 
many  men  (and  women)  will  be  closely  of  medium  height,  and  there  will 
be   other  striking  features   of  distribution  which  are  neglected  in  this 
rough  assortment. 

(2)  We  have  assumed   quite   independent   standards   for   men   and 
women.     This    is    an    assumption   already   familiar   in    statistical   work. 
Sir  Francis    Galton   at   the  outset  of  his  essay  "Natural  Inheritance" 
adopts    the   artifice   of  "never  dealing  with    female    measures    as   they 
are  observed,  but  always  employing  the  male  equivalents  in  the  place  of 
them  " :  and  without  this  artifice  he  declares  that  he  "  hardly  knows  how 
we  should  have  succeeded  in  making  a  fair  start." 

13.  With  these  qualifications  the  condition  (V.)  is    seen    to   be  in 
accordance  with  general  experience :  and  hence  it  follows — that  on  the 
average   the   child's   path    will   fall  just  midway  between   those   of  its 
parents — (VI.). 

14.  But  we  must  remember  that  this  result  is  only  the  extension  to 
the  case  of  two  parents  of  the  law  assumed  for  one  parent — i.e.  that  a 
child  resembles  its  parent.     It  is  therefore  liable  to  modifications  due  to 
any  departure  from  this  law  such  as  we  shall  presently  consider. 

15.  Sexual  restriction  of  deviation  from  type. — Now  suppose  OP  is 
the   general  type  of  a  species,  and    some   individual   follows   the   path 
OQ  differing  from  OP.     The  path  of  the 

mate  may  be  on  either  side  of  OP,  but 
will  on  the  average  be  along  OP:  and 
hence  the  children  will  on  the  average 
follow  the  midway  path  OR,  which 
diverges  from  OP  only  half  as  much  as 
OQ.  Hence  we  see  how  the  deviations 
of  the  parents  are  reduced  in  their  off- 
spring, and  the  tendency  to  diverge 
indefinitely,  noticed  in  §  9,  is  checked. 
We  shall  presently  show  that  definite 
limits  are  assigned  to  the  divergence,  but 

first  there  is  a  special  point  calling  for  notice,  which  might  modify  the 
conclusion  just  reached. 

1 6.  Assortative  mating. — An  assumption  (italicized)  was  made  in  the 
last   paragraph,  namely,  that  the  mate  is  chosen  indifferently  from  the 
community   at   large:    and    that    there   is  no    systematic  tendency,    for 
instance,   for  the  parents  to  resemble  one  another.     This   is  in  rough 
accordance  with  our  experience :  a  tall  man  does  not  as  a  rule  choose  a 
tall  wife ;  indeed  there  are  often  ludicrous  exceptions,  which  strike  the 
attention  so  much  that  we  should  say  that  the  tendency  was  the  contrary. 


522  APPENDIX 

It  is  doubtful,  however,  whether  ordinary  impressions  are  sufficient  to 
decide  with  accuracy  what  is  the  general  rule.  We  should  probably  be 
equally  surprised  to  find  on  careful  inquiry,  that  tall  men  chose  tall 
wives  in  as  large  a  percentage  of  cases  as  they  chose  short  wives  :  though 
a  small  percentage  would  not  be  surprising.  We  should  probably  admit 
that  the  matter  was  essentially  suitable  for  statistical  inquiry,  though  we 
should  not  expect  any  very  startling  results.  If  "like  on  the  whole 
chooses  like,"  then  the  divergences  of  parents  are  not  reduced  by  so 
much  as  one  half :  if  "  like  chooses  unlike,"  then  the  reduction  is  greater. 
Now  each  parent  has  many  qualities,  and  the  deviations  are  not  all  in  the 
same  direction.  A  tall  man  may  have  long  arms  and  long  legs,  but  he 
may  be  short  in  temper :  and  his  choice  of  a  mate  may  depend  as  much 
on  his  short  temper  as  on  his  long  arms.  Hence,  on  the  whole,  though 
statistical  inquiries  may  give  interesting  results  in  special  cases,  we  should 
reasonably  expect  to  find  that  the  path  of  the  child  was  that  of  the  "  mid- 
parent,"  and  that  the  deviations  of  the  parents  from  the  type  were  halved 
in  each  generation. 

17.  Definite  limits  for  divergence. — Now  suppose  that  a  snail  were  to 
start  crawling  away  from  a  wall,  and  were  to  crawl  one  foot  per  hour.     If 
it  were  undisturbed  it  would  ultimately  reach  an  indefinite  distance  from 
the  wall.     But  suppose  at  the  end  of  each  hour  some  one  put  it  back 
just  half-way  to  the  wall.     Then  the  course  of  events  is  as  follows  : — 

After  i  hour  it  has  crawled  to  1 2  inches  :  put  back  to  6 
„     2  „  „  1 8  inches:  „  9 

„     3  »  »  2I  inches:         -  „  ioj 

„     4  „  „  2 2\  inches:         „  n£ 

„     5  „  „  23 \  inches:         „  n| 

and  so  on.  Those  who  have  mathematical  knowledge  will  see  at  once 
that  the  snail  never  gets  two  feet  away  from  the  wall,  although  it  gets 
continually  nearer  and  nearer  to  that  distance :  and  indeed  without 
mathematical  knowledge  the  facts  are  fairly  obvious  :  for  so  long  as  the 
snail  does  not  reach  the  two  foot  mark  he  must  be  put  back  behind  the  one 
foot  mark,  and  thus  has  more  than  a  foot  to  go.  This  proves  the  first 
part  of  the  proposition — that  he  never  reaches  the  two  foot  mark.  The 
second  part  (that  he  gets  continually  nearer)  follows  from  the  fact  that 
his  failure  is  halved  each  time.  At  the  end  of  the  first  hour  he  fails  by  a 
whole  foot :  at  the  end  of  the  second  by  six  inches  :  at  the  end  of 
the  third  by  three  inches :  and  so  on.  The  defect  is  halved  each 
hour. 

1 8.  The    application    of    this    illustration    is    also    tolerably   clear. 
Children  have  a  tendency  to  deviate  from  their  parents,  and  if  unchecked 
the  deviations  from  the  ancestral  type  might  accumulate  (like  the  distance 
of  the  snail  from  the  wall)  to  any  amount.     But  if  the  deviation  is  halved 
every  generation,  a  certain  limit  cannot  be  surpassed,  though  it  is  con 
tinually  approached.     If  the  case  were  as  simple  as  that  of  the  snail  this 
limit  would  be  twice  the  deviation  of  any  generation  from  the  preceding — 
(VII.) :  but  the  problem  is  really  much  more  complicated.     Nevertheless, 
we  may  reasonably  anticipate  a  result  of  about  the  kind  indicated. 


ALTERNATIVE  SEXUAL  INHERITANCE 


523 


FIG.  7. 


19.  Limits  of  deviation. — The  limits  thus  assigned  will  be  of  course 
on  both  sides  of  the  ancestral  type.     They  are  not  necessarily  at  equal 
distances  from  it,  for  (owing  to  natural  selection  or  other  causes)  there 
may  be  more  tendency  to  diverge  on  one  side  than  on  the  other  :  and 
the  limit  will  be  proportionately  greater.     But  it  will  be  seen  that  we  have 
arrived  at  an  important  conception  of 

the  path  followed  by  a  descendant.     If 

OP  be  the  ancestral  type,   then  the 

paths  of  the  descendants  are  confined 

between  certain  limits,  OQ,  OR,  on 

opposite  sides  of  the  ancestral  type. 

These  limits  are  not  actually  defined 

so  sharply  as  we  have  drawn  them  ; 

they  are    more  like  the   edges   of  a 

shadow ;  and  an  accurate  mathematical 

expression  for  them  would  express  a 

gradual   shading  off — a  fall  rapid  at 

first  and  very  gradual  afterwards.    But 

if  for  simplicity  we  think  of  actually  well  defined  limits,  we  shall  not  be 

far  from  the  truth,  and  the  results  arrived  at  will  have  corresponding  exact 

propositions,  differing  from  them  only  in  detail. 

20.  Transmission   of  sexual  characters. — The  general   law  of  trans- 
mission above  considered  has  however  a  class  of  important  exceptions, 
applying  to  cases  where  the  differences  between  parents  are  not  small, 
and  are  not  continuously  graded.     The  most  conspicuous  and  important 
of  these  is  presented  by  the  sexual  characteristics  themselves.     The  child 
of  male  and  female  parents  is  not  something  midway  between  (with 
possible  extremely  rare  exceptions),  but  either  the  one  or  the  other.     We 
are  clearly  in  the  presence  of  a  totally  different  law  of  transmission. 

21.  We  can  illustrate  the  difference  graphically  by  adopting  separate 
planes  for  the  representation  of  the  two  sets  of  characters.     Our  diagrams 

have  hitherto  been  drawn  in 
one  plane,  OXY  :  if  we  devote 
this  plane  to  paths  such  as  OP, 
representing  the  growth  of  a 
female  organ,  we  shall  not  in 
general  be  able  to  represent 
the  growth  of  the  correspond- 
X  ing  male  organ  on  the  same 
diagram,  as  the  definitions 
would  not  apply.  But  we 
could  take  another  plane,  OXZ, 
in  which  OX  still  represented 
the  time  scale,  and  OQ  the 
FIG.  8.  growth  of  the  male  organ.  In 

so  far  as  the  organ  in  one  sex 

is  rudimentary  in  the  other,  we  could  of  course  represent  it  by  a  line 
near  OX  in  the  other.       Thus  if  OP  represents  the  growth  of  breasts 


524  APPENDIX 

in  a  female,  the  corresponding  growth  for  a  male  might  be  a  path  Op, 
very  close  to  X,  since  the  growth  is  slight.  And  if  the  organ  of 
one  sex  were  actually  non-existent  in  the  other,  it  could  nevertheless 
be  represented  by  the  line  OX  itself,  which  represents  zero  growth 
throughout. 

22.  So  that  each  sex  would  be  represented  by  two  sets  of  sexual 
characters,  "patent"   and   "latent"   as   Dr  Archdall   Reid   calls   them. 
"  Patent "  female  characters  would  be  represented  by  paths  such  as  OP 
far  from  OX,  in  the  special  female  planes  :  and  "  latent "  female  characters 
would  be  represented  by  paths  near  OX  (or  coinciding  with  it)  in  the 
special  male  planes  such  as  XOZ. 

23.  Now  we  know  that  our  principle  (IV.)  no  longer  applies  in  this 
case.     From  wide   experience  we  know  that — in  sexual  characters  the 
children   represent  either  one  parent  or  the  other:    not  both — (VIII.). 
Let   us    see   how   this  principle  can   be  represented   diagrammatically. 
To  avoid  the  complexities  of  solid  geometry,  let  us  make  a  cross  section 
of   Fig.   8    through   the   lines    PTQ,    as    represented   in    Fig.    9.     The 

point  T  represents  rudimentary  or 
zero  characters,  P  well  developed 
female,  and  Q  well  developed  male. 
Now  the  child  has  two  sets  of 
qualities :  we  may  represent  him  by 
a  pair  of  points,  AB,  connected  to- 
gether, or  rather  kept  separate  by  a 
rigid  rod.  (The  notion  of  keeping 

""""  Q        separate    is  appropriate,    because  he 

has    one   set   patent  and    the    other 

t  latent :  not  both  patent  or  both  latent, 

A2  B2    i.e.    A    and    B    must    not    coincide.) 

FIG.  9.  Experience  then    tells    us   that    there 

are  two  possible  positions  of  AB,  as 

crudely  represented  in  Fig.  9  :  either  A  falling  on  P  and  B  on  T,  or 
A  on  T  and  B  on  Q. 

24.  This  result  would  follow  at  once  if  we  conceive  of  P,  T,  and  Q 
as  centres  of  attraction  for  the  ends,  A,B,  of  the  rod.     And  this  conception 
would  be  quite  in  keeping  with  what  has  gone  before:  thus  in  Fig.  7 
we  might  regard  the  type  path,  OP,  as  attractive,  so  that  other  paths  would 
be  attracted  near  it.     If  we  took  a  cross  section  of  the  path  as  we  did 
for  those  of  Fig.  8,  we  should  get  a  single  point,  P,  representing  the  parent, 
attracting  the  single  point,  R,  representing  the  child.     When  we  come  to 
sexual  characters  we  must  represent  the  child  by  two  points  as  above  : 
and  we  then  get  a  new  interpretation. 

25.  It  is   scarcely  necessary  to   say  that  the   diagrammatic  analogy 
proves  nothing  whatever.     It  is  merely  a  convenient  summary  of  facts 
which  we  learn  from  wide  experience.     But  it  may  help  us  to  realize 
the  connexion,  with  these  fundamental  and  well  known  facts,  of  others 
which  are  not  so  well  known. 

26.  For  instance,  it  may  help  us  to  realize  how  Mendelian  inheritance 


ANCESTRAL  INFLUENCE 


525 


is  analogous  to  sexual  inheritance,  as  Dr  Reid  has  argued.  Mendelian 
inheritance  deals  with  the  combination  of  two  characters,  one  of  which 
is  patent  and  the  other  latent  or  non-existent.  It  could  be  represented 
graphically  by  the  same  artifice  used  for  sex.  But  properly  to  develop 
the  consequences  requires  a  more  careful  study  of  the  phenomena  than 
the  present  writer  has  been  able  to  undertake. 

27.  Ancestral  resemblance. — Let  us  now  return  to  those  qualities 
which  are  transmitted  non-sexually.  We  have  hitherto  dealt  simply  with 
the  resemblance  of  children  to  their 
immediate  parents ;  but  we  know  that 
inheritance  is  not  from  parents  alone. 
From  wide  experience  we  know  that — 
a  child  has  a  tendency  to  resemble, 
not  only  its  immediate  parents,  but  its 
ancestors,  even  when  the  parents  differ 
from  them — (IX.). 

Hence  if  OP  be  the  ancestral  type, 


FIG.  10. 


and  OQ  the  path  of  a  parent,  the 
path  of  the  child,  Oq,  will  tend  to  lie 
between  OQ  and  OP :  but  there  is 
no  reason  why  it  should  be  midway  between  OQ  and  OP :  probably  it 
lies  nearer  OQ,  though  we  may  not  be  able  to  deduce  the  numerical  law 
from  theoretical  considerations.  Sir  Francis  Gal  ton  found  in  1889  that 
in  certain  cases  Pq=  2  Qq :  or  Pq  =  f  PQ  :  i.e.  the  deviation  of  a  child 
was  f  of  the  deviation  of  a  parent:  and  this  may  quite  possibly  be  a 
general  law  deducible  from  theoretical  considerations.  On  the  ocher 
hand,  the  numerical  factor  may  differ  in  every  case.  For  the  present,  we 
shall  merely  use  Sir  Francis  Galton's  result  for  the  purpose  of  illustration 
without  attempting  to  explain  it,  or  inquire  into  its  generality. 

28.  Corrected  statement  of  sexual 
effect. — Thus  if  one  parent  alone  (OQ) 
were  concerned,  the  child  would  tend  to 
follow  the  path  Oq,  where  Pq  =  f  PQ. 
If  the  other  parent  (OR)  were  alone 
concerned,  the  child's  path  would  tend 
to  be  Or,  where  Pr=f  PR.  When 
both  parents  are  concerned,  the  child's 
path  will  therefore  tend  to  lie  midway 
between  Oq  and  Or,  not  midway  be- 
— -  tween  OQ  and  OR  as  previously  stated. 
The  deviation  from  OP  will  consequently 
be  §  of  that  previously  stated,  which 
we  found  was,  on  the  average,  one  half  that  of  the  parents.  Hence  the 
deviation  will  be  reduced  every  generation,  not  in  the  ratio  \  which  is 
the  sexual  effect,  but  in  the  ratio  f  X  J  =  J,  which  is  the  combined  sexual 
and  ancestral  effect.  Returning  to  the  analogy  of  the  snail,  if  at  the  end  of 
each  hour  one  person  sets  him  back  to  half  his  distance,  and  another 
person  to  f  of  that  half,  he  will  always  be  set  back  to  J  of  his  total 


FIG.  ii. 


526 


APPENDIX 


distance  :  and  it  is  then  clear  that  his  limit  will  be  reduced  from  24  inches 
to  1 8  inches.  So  long  as  he  is  short  of  the  18  inch  mark  he  will  be 
set  back  behind  the  6  inch  mark,  and  will  thus  have  more  than  a 
foot  to  do  to  reach  18  inches.  He  will  thus  never  get  there,  though 
he  will  continually  approach  it.  The  effect  of  ancestral  inheritance 
is  to  reduce  the  limits  of  deviation  from  type  which  we  arrived  at 
in  §  10. 

29.  Stability  of  type. — We  have  thus  arrived  at  a  very  definite  notion 
of  the  stability  of  a  type  when  no  cause  such  as  natural  selection  interferes 
with   it.     Mating   alone    would   suffice   to    prescribe    certain   limits    of 
deviation  from  the  ancestral  type  which  could  not  be  exceeded. 

30.  These  limits  are  narrow — a  simple  analogy  suggests  as  average 
limit  twice  the  average  deviation  of  a  single  generation :  and  though  a 
more  suitable  but  more  complex  calculation  might  give  a  rather  different 
result,  the  limits   are    not  likely  to    be  many  times  greater   than   the 
deviations  from  one  generation  to  the  next. 

31.  Similarly  the  tendency  of  descendants  to  resemble  their  ancestors 
causes  a  reversion  to   the  type  in  each  generation,  which  narrows  the 
limits  still  further. 

32.  We  shall   presently  point  out  an  important  difference  between 

the  action  of  these  two  agencies,  the 
sexual  and  the  ancestral ;  but  at  present 
we  are  concerned  with  their  con- 
currence. Together  they  restrict  the 
deviation  within  narrow  limits  and 
render  the  type  stable. 

3  3 .  Paring  down  of  irregularities. — 
It  is  perhaps  worthy  of  note  that  the 
two  agencies  combine  to  destroy,  not 
only  deviations  of  the  whole  path  OV 
-jj  from  OP,  but  also  irregular  deviations 
such  as  OSQR,  which  may  cross  the 
type  path.  The  portion,  OSQ,  which 

lies  above  OP,  will  tend  to  be  replaced  in  the  next  generation  by  OsQ,  still 

above  but  less  above :  at  Q  there  is  no 

tendency  to  change,  and  in  the  portion, 

QTR,  the  influence  is  to  raise  the  path 

towards  OP.    Thus  the  path  of  the  child 

tends    to    straighten    out    irregularities 

in  those  of  the  parents.     Indeed  it  is    «. 

easily  seen   that    irregularities    of  this 

kind  have,  owing  to  the  sexual  effect, 

far  less  chance  of  surviving  than  have 

deviations    of   the    path    as    a  whole, 

either  above  or  below,  for  the  paths  of 

the    parents   may   easily  both    deviate 

in  one  direction  as  a  whole,  but  their 

irregularities  would  be  unlikely  to  coincide,  and  would  tend  to  annul  one 


FIG.  12. 


FIG.  13. 


PROGRESS  MEANS  EARLY  DEVELOPMENT        527 

another.  Hence  if  OP  be  the  type-path,  we  may  take  as  representative 
individual  paths  OKR  and  OMQ,  lying  near  OP,  but  not  as  a  rule 
crossing  it— -(X.). 

34.  Earlier  development. — Now  this  has  an  important  consequence. 
Instead  of  drawing,  as  hitherto,  ordinates  such  as  QPRT,  parallel  to  the 
OY  axis,  draw  one  NMLK  parallel  to  the  OT  axis.     Then  NM  or  OV 
represent  the  time  at  which  the  child,  OQ,  has  the  organ  under  consideration 
of  the  same  size  (MV  or  LX)  as  the  parent  at  the  time  OX.     The  child, 
OQ,  reaches  this  stage  earlier  than  the  parent ;  and  since  the  same  is  true 
throughout  the  curve  we  see  that  this  child  passes  through  all  the  successive 
stages   (in   regard   to    the   organ    in  question)    earlier   than   its    parent. 
Similarly  the  child,  OR,  develops  more  slowly  than  its  parent,  throughout. 
We  may  say  generally  that — individuals  strong  in  any  organ  develop  early ; 
those  weak  develop  late — (XI.). 

35.  Relation  of  organs. — But  we  have  so  far  considered  one  organ 
alone,  whereas  the  characteristics  of  any  animal  depend  on  the  relation  of 
its  parts — small  head  and  long  neck 

in  a  giraffe :  large  head  and  short 
neck  in  a  lion.  What  is  true  of  an 
isolated  organ  may  not  be  true  of  a 
combination,  and  we  must  consider 
how  the  relationship  of  one  to  another 
enters  into  the  questions  before  us. 
In  the  first  instance,  take  any  two 
organs  such  as  length  of  leg  and 
weight  of  brain  :  and,  dropping  any 
question  of  time  for  the  moment,  let 
us  make  a  diagram  to  represent  their 
relationship,  setting  off  the  length  of 
leg  along  OZ,  and  the  weight  of  brain  along  OV.  Thus  the  point  P  repre- 
sents the  fact  that  when  the  length  of  leg  is  4  feet,  the  weight  of  brain  is 
3  ounces  or  pounds,  or  any  other  suitable  unit.  Previously  (at  Q)  the 

length  of  leg  was  2  feet,  and  the  weight 
of  brain  was  i  oz.  or  Ib.  Since  the 
dimensions  are  all  zero  at  first,  the  path 
PQ  will  start  from  O,  just  as  that  repre- 
senting the  relation  bet  ween- any  organ 
(say  Y)  and  the  time. 

36.  Now  it  will  easily  be  seen  that 
most  of  the  considerations  already 
advanced  in  the  case  of  the  paths  for 
Z  the  growth  Y  of  an  organ,  with  the 
time  T,  will  apply  equally  well  to  the 
path  for  the  growth  of  one  organ 
relatively  to  another.  If  OQP  is  the  path  for  a  parent,  and  Oqp  that  of 
a  child,  the  facts  that  children  roughly  resemble  parents,  but  that  they 
may  differ  from  them  in  either  direction,  and  so  on,  still  apply  to  these 
new  paths.  Hence  we  get  the  same  rules  about  sexual  and  ancestral 


P 

y 

Q 

^X 

^ 

;>                             2342 

Length  cfLeg 

FIG.  14. 

FIG.  15. 


528 


APPENDIX 


FIG.  16. 


effect,  and  we  are  led  in  the  same  way  to  the  limits  of  deviation  from  the 
type. 

37.  If  OP  be  the  type-path  it  may  indeed  be  a  more  devious  curve 
than  those  we  have  considered.    But  the  descendants  will  have  paths  lying 

within  narrow  limits,  such  as  OQ 
and  OR.  And  the  same  will  be 
true  of  any  pair  of  organs  :  so  that 
the  infinite  complexities  of  growth 
and  structure  of  the  whole  animal 
will  all  be  reproduced  within 
narrow  limits  in  the  developments 
of  their  descendants. 

38.  Earlier  and  later  develop- 
ment.— But  now  let  us  reinsert  the 
time  element.  Of  the  individuals 
which  follow  any  given  path,  OQ, 
reaching  any  stage,  L,  on  the  average 
at  a  given  time,  some  will  have  developed  rather  more  rapidly  and 
reached  K ;  others  more  slowly  only  and  reached  M.  We  could 
represent  the  time  scale  in  the  same  diagram  by  marking  off  various 
epochs  on  the  curve.  But  we  should  always  have  to  remember  that  some 
individuals,  while  still  keeping  near  the  type,  arrived  at  any  given  stage 
early,  and  some  arrived  late.  It  is  not  difficult  to  see  that  the  rule  XII. 
specified  in  |  34  applies,  not  to  a 
single  organ  alone,  but  to  the  whole 
complexities  of  animal  structure.  We 
can  thus  return  to  our  curves  repre- 
senting the  variations  of  a  single  organ 
with  the  time,  knowing  that  the  results 
obtained  can  be  extended  in  this  way. 

39.  Order  of  the  quantities. — It  is 
perhaps  worth  while  to  consider  for 
a  moment  the  size  of  the  quantities 
involved — what  a  mathematician  calls 
their  "  order."  Thus  if  PT  represents 
the  height  of  a  parent,  say  6  feet,  then  the  average  deviation,  PQ,  is 

something  like  an  inch  or  two — say 
i  in  50  :  and  SP  will  be  nearly  the 
same  fraction  of  OT.  If  OT  be  the 
time  taken  to  grow  to  full  height,  say 
25  years,  then  SP  will  be  about 
6  months.  The  child  who  is  going  to 
be  taller  than  his  parent  by  -^th  part 
will,  on  this  computation,  reach  a 
similar  height  about  6  months  earlier. 
But  usually  growth  is  rapid  at  first 
and  slow  nearer  maturity,  so  that  the 
figure  should  be  like  Fig.  18  rather  than  Fig.  17.  It  is  easily  seen  that 


FIG.  17. 


FIG.  18. 


NATURAL  SELECTION 


529 


the  child  will  under  these  conditions  anticipate  the  parent  by  more 
still.  This  anticipation,  or  early  development,  is  of  importance  as  will 
be  seen  presently. 

40.  Natural  selection. — We  now  come  to  the  agency  that  modifies 
the  above  conclusions,  natural  selection,  which  works  by  the  destruction  of 
the  defective.     Let  us  represent  the 

growth  of  the  particular  character 
which,  by  defect,  renders  the  animal 
liable  to  destruction  by  paths  be- 
tween OQ  and  OR,  in  the  manner 
already  familiar.  Then  if  the  animal 
does  not  reach  a  certain  lower  limit, 
OD,  in  this  character,  it  is  liable 
to  destruction — for  simplicity  let  us 
say  it  is  actually  destroyed.  But 
this  liability  does  not  commence  at 
birth:  animals  are  usually  protected 
by  their  parents,  sometimes  for  long 

periods,  after  birth.  The  period  of  protection  may  be  represented  in 
the  time  scale  by  OM,  so  that  the  animal  is  not  liable  to  be  destroyed 
until  its  path  has  reached  the  ordinate  MV.  If  then  all  who  have 
not  reached  the  limit,  OD,  are  destroyed,  the  survivors  will  be  those 
following  paths  between  OVW  and  OLQ.  This  is  the  main  argument 
stated  in  its  most  elementary  form  :  but  in  this  form  it  is  scarcely 
applicable  to  real  life :  we  must  generalize  the  details. 

41.  Period  of  protection. — First  let  us  consider  the  period  of  parental 
protection,  which  is  often  evanescent.     If  the  argument  were  no  longer 
applicable   in    such  cases,    we  should   have   a   serious    difficulty.     But 
parental  protection  is  only  one  form  of  a  more  general  protection  in 
which  chance  plays  a  conspicuous  part.     Let  us  first  consider  a  number 
of  seeds  scattered  on  the  ground  and  liable  to  be  eaten  by  birds.     A  seed 
may  be  snapped  up  directly  it  is  scattered,  or  it  may  never  be  eaten  at 
all :  and  though  there  is  thus  no  definite  protection,  there  will,  according 
to  the  laws  of  probability,  be  an  "  expectation  of  life  "  of  a  seed — an 
average  period  for  which  it  may  expect  to  survive.     And  this  period  will 
not  be  determined  by  inherent  qualities  of  the  seed,  but  by  external 
circumstances,  such  as  the  number  of  depredating  birds,  the  nature  of 
the  soil,  and  the  skill  of  the  sower.     There  is  something  very  similar  in 
the  case  of  young  animals  too  feeble  to  depend  on  their  own  exertions  for 
escape  from  destruction.     In  later  life  an  animal  may    depend  on   its 
speed  for  escape,  and  the  speediest  will  have  advantages  over  those  less 
speedy :  but  the  speed  of  the  very  young  may  not  suffice  in  any  case  to 
protect  them :  slow  and  speedy  may  be  open  to  similar  risks,  like  two 
seeds  or  two  eggs  in  the  same  nest. 

42.  Hence  the  notion  of  the  period  of  protection  when  generalized 
will   be  somewhat  complex  :  it  will  include  not  only  the  period  before 
birth  (for  viviparous  animals),  or  the  period  in  the  egg  and  in  the  nest 
after  hatching :  but  also   an    additional    period  before   the   powers   are 

34 


530  APPENDIX 

sufficiently  developed  to  give  one  individual  sensible  advantages  over 
another :  the  protection  will  in  general  be  only  partial,  and  the  period 
will  vary  greatly  in  length  for  different  individuals.  It  will  be  definite 
only  in  the  sense  in  which  an  average  is  definite :  and  its  essential 
characteristic  is  that  it  is  not  determined  by  differences  between 
individuals,  but  by  external  causes :  so  that  it  is  properly  represented  by 
a  vertical  ordinate,  MKL  in  Fig,  19,  which  cuts  all  paths  at  an  equal 
distance  from  OY. 

43.  The  destructive  limit. — Let  us  now  consider  the  destructive  limit, 
represented  by  a  line,  DV,  cutting  all  the  paths  at  an  equal  distance  from 
the  other  axis.     One  criticism  which  may  be  made  is  that  this  representa- 
tion is  not  always  appropriate,  since  the  quantity  of  any  character  required 
for  escaping  destruction  may  vary  during  the  life-time  of  the  individual. 
Thus  if  an  animal  depended  for  escape  on  length  of  leg,  doubtless  shorter 
legs  would  suffice  in  its  youth  to  carry  it  into  safety  than  when  it  became 
older  and  heavier  :  hence  it  might  be  said  that  the  line,  DV,  ought  to 
slope  upwards.     But  we  can  make  a  horizontal  line  suit  such  cases  by 
changing  the  character  represented  in  the  diagram.     Instead  of  length  of 
leg,  let  us  take  actual  speed :  then  the  speed  required  in  all  cases  would 
be  the  same  (namely,  that  which  outstrips  the  enemy),  and  hence  the 
horizontal  line  would  be  appropriate.     By  choosing  the  right  variable,  we 
can  make  our  diagram  suit  other  cases. 

44.  Effect  on  next  generation. — We  may  now  consider  the  effect  of 
this  destruction  on  the  next  generation.     The  survivors  represented    by 
paths  between  OVW  and  OQ  in  Fig.  19,  are  stronger  in  the  particular 
quality  than  those  destroyed,  and  their  children  will  tend  to  be  like  them. 
We  shall  have  to  take  account,  in  this  connexion,  of  sexual  and  ancestral 
influences ;  but  let  us  omit  these  in  the  first  instance,  for  separate  con- 
sideration later.     We  thus  simplify  the  problem  to  the  case    in    which 
children  merely  tend  to  resemble  their  parents. 

45.  By  a  slight  extension  of  the  significance  of  the  diagram  we  can 
use  it  to  represent  the  members  of  one  generation  in  all  stages  of  growth. 
Thus  those  destroyed    in    a   generation  are  represented    by   the    figure 
VWRK,    the    survivors    by    LVWQ,   and    those    who    are    still    being 
protected  by  the  triangle  OKL.     These  last  may  in  general  be  dismissed 
from  consideration  when    we   are   discussing   the    next   generation :  for 
usually  breeding  does  not  commence  until  the  period  of  protection  is 
over,  and  the  animal  is  thrown  on  its  own  resources.     The  parents  of 
the  next  generation  will  thus  be  represented  simply  by  the  figure  LVWQ, 
and  their  children  will  thus  tend  to  follow  paths  between  OW  and  OQ. 

46.  Thus  the  primary  result  of  destroying  the  unfit  is  to  improve  the 
next  generation.     The  type-path  tends  to  rise,  and  will  continue  to  rise 
as  the  destruction  is  repeated  until  the  paths  all  clear  the  point  V  in  Fig. 
1 9  :  that  is  to  say  the  character  represented  will  gradually  improve.     It 
will  probably  go  on  improving  even  after  the  point  V  is  cleared :  for  V 
itself  will  tend  to  rise,  since  one  animal  is  often  the  prey  of  another,  and 
the  struggle  between  them  will  tend  to  improve  both. 

47.  The  point  V  may  also  move  to  the  left.     For  the  children  of  the 


MATURITY 


/ 


O, 


v 


survivors  run  through  the  stages  when  they  need  protection  more  quickly 

than   the  generation  before  them.      Now    .. 

the  protection  itself  is  a  product  of  natural 

selection,    and   will    not    be    maintained 

without  reason.    Hence  as  each  generation 

needs  it    for    a    shorter    period    (on    the 

average)    it    may   shorten    automatically. 

Hence  O  moves  to  the  left  and  upwards 

from    a  position  such  as  V1  to    another 

such  as  V2;    and  the   path    representing 

the  growth  of  the  character  which  deter- 

mines destruction  or   survival  will    move 


from    OPj  to  OP2  :    that  is,  its  gradient 


M2 

FIG.  20. 


M, 


will  become  steeper,  at  any  rate  until  it 

has    surmounted  the  point  V.     As  to  what  happens  after  this  we  will 

inquire  presently. 

48.  Now  in  §  15  it  was  pointed  out  that  this  means  earlier  develop- 
ment of  the  organ  or  character ;  and  thus  we  see  the  effect  of  natural 
selection  is  to  make  organs  on  which  it  acts  develop  early. 

49.  Other  organs. — Again  there  is  nothing  impossible  in  the  associa- 
tion of  an  early  development  of  organ  Y  with  retarded  development  of 
organ  Z.     But  if  Y  and  Z  are  both  acted  on  by  natural  selection  there 
will  be  a  tendency  for  both  to  develop  early  ;  and  the  relative  proportions 
of  the  animal,  so  far  as  these  two  organs  are  concerned,  will  tend  to  be 
preserved  while  at  the  same  time  its  development  is  accelerated.     But 
natural  selection  acts  on  an  immense  number  of  characters  in  a  complex 
animal,  and  the  same  argument  will  extend  to  them  all.     Hence  there  is 
a    continual  tendency  to  preserve  those  individuals  which  run  quickly 
through  the  copies  set  them  by  their  parents,  at  any  rate  until  they  reach 
the  destructive  limit. 

50.  Modification  of  curve. — But  now  what  happens  after  reaching  this 
We  return  to  the  case  of  a  single  organ  for  simplicity.     Once  the 

limit  is  attained,  and  the  individual  is 
secure  of  survival,  he  may,  so  to  speak, 
please  himself  whether  he  goes  further. 
Those  who  survive  at  V  may  go  on 
to  Q  or  only  to  R,  and  their  children 
will  be  equally  numerous.  Now  we 
have  hitherto  dealt  with  straight  paths 
and  regarded  such  a  path  as  OVR  as 
unusual:  but  this  was  before  the  idea 
—  of  natural  selection  was  introduced  ;  and 
X  we  shall  presently  see  reasons  for  modi- 
fying the  results  previously  arrived  at.  We 
shall  find  in  fact  that  influences  tending  to  depress  the  portion  VQ  to  VR ; 
so  that  after  a  certain  point  the  growth  is  slower  than  at  first.  This  is  a  well- 
known  feature  of  the  growth  of  all  animals  and  plants  :  after  a  certain  point 
they  reach  "  full  growth,"  and  further  development  is  comparatively  slow. 


limit  ? 
Y 


FIG.  21. 


532 


APPENDIX 


FIG.  22. 


51.  »S<?#w<2/  ^^5  combined  with  natural  selection. — We  now  turn  to 

the  modifications  introduced  by  mating.  Let  us  suppose  that  the  destruc- 
tion of  the  unfit  has  produced  a 
rise  from  the  ancestral  type  OP  to 
Op.  Then  the  reasoning  of  §  15 
shows  how  mating  sets  certain  limits 
OQ,  OR  for  deviation  from  the  type 
Op  :  but  suggests  no  general  tendency 
to  return  towards  OP. 

52.  But  there  is  a  particular 
tendency  of  this  kind  arising  from 
the  sexual  effect,  in  connexion  with 
the  paring  down  of  irregularities.  If 
OP  be  the  type,  then  we  have  re- 
marked that  such  irregular  paths  as 

OrKR  tend  to  disappear  because  in  effect  there  are  equally  likely  paths, 

OqKQ,    with    which    they    may    be 

mated.     But  under  natural  selection 

the    paths    are    not    equally    likely. 

The   path    OrKR    climbs    over  the 

V  and  indicates  survival :   the  paths 

OqKQ    does  not  surmount  V,    and 

means  destruction.    Thus  paths  such 

as    OrKR    get   the   advantage    and 

survive.     This  is  the  first  cause  for 

the  depression   of  path   noticed   in 

§  50- 

53.    Ancestral     inheritance     and 
natural  selection. — Let  us  now  consider  ancestral  inheritance.     As  before, 

let  OP  be  the  ancestral  type,  DV 
the  destructive  limit,  and  suppose 
the  type  has  risen,  under  the 
influence  of  natural  selection,  to 
OQ.  Then  by  virtue  of  ancestral 
inheritance  there  is  a  continual 
tendency  for  every  point  of  OQ 
to  return  to  OP;  and  this  acts 
in  the  contrary  direction  to 
natural  selection,  and,  at  any 
rate,  checks  indefinite  departure 
from  the  original  type. 

54.  But  is  it  sufficient  to  arrest 
it  ?  In  whatever  form  we  think  of 
ancestral  influence,  we  cannot  avoid  contemplating  it  as  becoming  weaker 
in  each  succeeding  generation.  Suppose  for  a  moment  that  for  a  particular 
generation  the  tendency  of  natural  selection  to  raise  the  type  were  just 
counterbalanced  by  the  tendency  of  ancestral  influence  to  depress  it. 
For  the  next  generation  the  depressing  influence  would  be  weaker,  and 


FIG. 


M 

23- 


FIG.  24. 


RETROGRESSION  533 

the  type  would  rise :  there  seems  no  escape  from  the  continual  rising  at 
any  rate  so  far  as  the  critical  limit  D  V.  But  beyond  this  limit,  natural 
selection  ceases  to  work,  and  ancestral  influences  act  unchecked.  Hence 
LQ  will  tend  to  move  nearer  OP,  i.e.  in  the  direction  LR.  This  is  the 
second  cause  for  the  depression  of  the  path  noticed  above. 

55.  Retrogressive  tendency. — But  as  yet  we  have  found  nothing  to 
arrest  continual  and  indefinite  departure  from  the    original  type  up  to 
the  point  V.     There  is  nothing  which  can  permanently  balance  natural 
selection,  so  that  the  type  may  remain  stable  in  the  presence  of  its  natural 
enemies.     And  yet  our  experience  is  that  such  stability  is  reached.     If 
we  admit  the  existence  of  such  stability,  then  we  may  put  the  inference 
as  follows  :  Let  any  generation  consist  of  A  individuals  who  are  destroyed 
before  breeding,  and  B  individuals  who  survive  and  have  offspring.     If  a 
condition  of  stability  is  reached  the  next  generation  will  be  the  same — 
A  unfit  and  B  fit.     But  all  these  are  by  hypotheses  the  offspring  of  the 
B  members  only  of  the  preceding  generation.     These  B  members  do  not, 
therefore,  produce  offspring  B,  fit  like  themselves  (on  the  average),  but 
partly  B  and  partly  A ;  the  average  of  the  offspring  is  lower  than  that  of 
the  parent :  and  this  goes  on  continually.     The  parents  are  of  a  constant 
type  B  :  the  children  are  of  a  constant  inferior  type  between  B  and  A. 
If  the  difference  remains  really  constant,  ancestral  resemblance  cannot 
explain  it,  for  this  is  all  the  time  growing  weaker.     We  seem  to  be  thrown 
back  on  some  innate  tendency  to  retrogression,  which  may  possibly  be  a 
universal  tendency.     We  assumed  at  the  outset  that  children  might  deviate 
from  their  parents  in  either  direction :  but   the  deviations  may  not  be 
equal.     We  should  have  a  vera  causa  of  the  kind  we  are  looking  for  if  the 
tendency  to  retrogression  were  the  stronger.     It  is  not  necessary  that  it 
should  be  always  stronger;  it  would  suffice  if  it  became  stronger  with  growth. 

56.  Dr   Archdall    Reid  has,   however,  no  hesitation  in   stating  the 
principle  in  a  universal  form.     He  wrote  to  me  on  July  16,  1909:  "In 
all  structures  retrogressive  variations  tend  to  predominate,  and  do  in  the 
long  run  predominate  over  progressive  variations.     Therefore  we  get — 

(a)  Retrogression  on  relaxation  of  selection,  and  more  especially  on 
cessation  of  selection. 

(ft)  Stability    of    type   when    selection    balances    the    tendency    to 
retrogression. 

(c)  Progression  when  the  strin- 
gency of  selection  is  sufficient  to 
overcome  the  tendency  to  retro- 
gression (reversion)." 

He  adds  that — 

"Retrogressive  variations  tend 
to  be  prepotent  in  a  blend,  i.e.  the 
retrogressive  parent  is  on  the  average 
better  represented  in  the  blend." 

57.  I  am  not  clear  whether  this  is  really  an  additional  effect. 
Suppose  OPt  and  OP2  to  represent  the  parents,  OP2  being  the  retro- 
gressive.    Then  according  to  the  law  of  individual  retrogression  the  child 


534  APPENDIX 

of  OPj  would  in  any  case  regress,  say  to  Op: :  and  the  child  of  OP2  to 
Op2.  Hence  without  any  additional  effect  due  to  blending  the  child  of 
both  parents  would  tend  to  be  midway  between  OPj  and  OP2,  which 
is  nearer  to  OP2  than  to  OPX :  so  that  the  retrogressive  parent  would  be 
better  represented  in  the  blend  in  any  case.  Is  the  prepotency  intensified 
by  the  blending  ?  It  is  clear  that  we  are  now  on  totally  different  ground, 
where  we  no  longer  depend  on  our  every  day  experience,  but  require  the 
guidance  of  specialists,  who  have  observed  the  phenomena  more  closely. 

58.  This  essay  then  comes  to  a  natural  termination.  But  if  the 
reasoning  is  correct,  we  have  been  able  to  show  that  we  can  deduce  from 
well  known  laws,  combined  with  the  principle  of  natural  selection. 

1 i )  The  value  of  sex  in  restricting  deviation  from  type. 

(2)  The  tendency  to  run  through  early  development  more  and  more 
quickly,  thus  compressing  the  past  history  and  leaving  time  for  adding 
to  it. 

(3)  The  cessation  of  growth,  or  comparative  slowness  of  growth,  on 
reaching  maturity. 

(4)  The  probable  existence  of  an  inherent  tendency  to  retrogression, 
other  than  the  ancestral. 

It  follows  then  that  such  facts  as  (2)  and  (3),  which  we  can  independ- 
ently verify  from  wide  experience,  are  independent  verifications  of  the 
wide  working  of  natural  selection. 


GLOSSARY 

ACQUIRED,  acquirement ;  terms  intended  by  biologists  to  indicate  alterations  in  the 
individual  caused  by  the  action  of  environment  on  his  mind  and  body.  Since,  however, 
all  characters  arise  as  a  reaction  to  the  environment  the  terms  are  misleading.  They 
really  designate  traits  that  arise  under  the  stimulus  of  use  and  injury. 

ALLELOMORPH  ;  an  '  alternative '  unit,  believed  by  the  followers  of  the  Mendelian 
hypothesis  to  exist  in  the  germ-plasm,  which  is  supposed  to  be  compounded  of  such 
units. 

BIOMETRY  ;  the  measurement  and  statistical  treatment  of  biological  phenomena. 
BI-PARENTAL  ;  see  cell. 

CELL  ;  a  living  entity,  usually  microscopical,  typically  possessing  a  cell-wall,  with  living 
protoplasmic  contents  (the  cytoplasm}  in  which  is  embedded  a  nucleus.  Within  the  nucleus 
is  a  substance  termed  chromatin,  which  is  differentiated  from  the  rest  of  the  nucleo-plasm. 
Cells  multiply  by  self-division,  the  mother-cell  constricting  itself  and  dividing  into  two 
daughter-cells.  Before  division  occurs  the  chromatin  of  the  nucleus  usually  gathers  itself 
into  masses  termed  chromosomes,  the  number  of  which  is  definite  for  each  species.  On  the 
nucleus  depends,  apparently,  the  nature  of  the  cell,  and  therefore  the  nature  of  the  in- 
dividual that  develops  from  the  germ-cell.  Consequently,  it  is  probable  that  the  nucleus 
contains  all  or  most  of  the  germ-plasm,  the  substance  which  is  the  '  bearer  of  heredity,' 
which  carries  the  hereditary  tendencies  or  developmental  potentialities.  The  germ-plasm 
has  been  identified  with  some  show  of  reason  with  the  chromatin.  Unicellular  animals 
and  plants  consist  each  of  a  single  cell,  the  daughter-cells  of  which  separate  and  become 
distinct  individuals.  Each  cell  therefore  performs  all  the  functions  of  life.  On  the  other 
hand,  a  multicellular  organism  is  compounded  of  two  or  more  cells.  It  takes  origin  in 
a  single  cell  (which  is  usually  a  fertilized  ovum).  The  daughter-cells  in  the  successive 
generations  do  not  separate.  Consequently  the  individual  may  consist  of  billions  of  cells, 
all  of  which  are  differentiated  to  perform  special  functions — e.g.  locomotion,  secretion, 
reproduction  of  new  individuals  (cell-communities).  The  cells  of  the  multicellular  organ- 
ism which  are  immediately  concerned  with  the  reproduction  of  new  individuals  are 
termed  germ-cells.  All  the  others  (e.g.  muscle,  skin,  and  nerve  cells)  are  termed  somatic 
cells,  and  together  constitute  the  soma,  the  main  mass  of  the  body  of  the  individual. 
Since  unicellular  organisms  are,  in  effect,  germ-cells,  they  have,  of  course,  no  soma.  The 
germ-cells  of  multicellular  organisms  are  termed  sperms  (spermatozoa)  and  ova.  In  the 
case  of  plants  they  are  termed  pollen-grains  and  ovules  respectively.  Sperms  are  derived 
from  the  male,  ova  from  the  female  reproductive  organs.  A.  fertilized  ovum  is  formed 
by  the  union  of  a  sperm  with  an  ovum.  Apparently  this  act  of  conjugation  consists 
essentially  in  a  union  of  nuclei  which  involves  a  more  or  less  intimate  union  of  the  contained 
chromatin.  In  some  species  each  individual  is  an  hermaphrodite  ;  that  is,  it  possesses 
both  male  and  female  organs  and  produces  both  sperms  and  ova.  In  the  great  majority 
of  species,  including  of  course  all  those  types  the  individuals  of  which  are  male  or  female 
and  produce  only  sperms  or  only  ova,  the  germ-cells  of  the  individual  conjugate  only 
with  germ-cells  from  another  individual.  The  reproduction  is  then  bi-parental.  In  some 
species,  however,  there  is  self-fertilization  ;  that  is  the  sperms  and  ova  of  the  same 
hermaphrodite  conjugate.  Some  species  produce  only  ova,  which,  without  being  fertilized, 
develop  into  individuals.  This  mode  of  reproduction  is  termed  parthenogenesis.  Between 
the  germ-cell,  fertilized  or  not,  whence  a  multicellular  individual  is  derived  and  the  germ- 
cells  contained  in  his  (or  her)  own  body,  lie  generations  of  cells,  the  ancestors  of  the  germ- 
cells,  which,  like  the  cells  of  the  soma,  do  not  conjugate  with  other  cells.  These  are  the 
generations  of  the  germ-tract.  When  reproduction  is  by  means  of  germ-cells  it  is 
termed  sexual;  when  it  is  by  means  of  slips,  buds,  suckers,  and  the  like,  it  is  a-sexual. 

CELL-COMMUNITY  ;  see  cell. 

CHARACTER  ;  any  trait  of  an  individual — e.g.  his  head,  a  hair,  the  colour  of  a  hair. 

CHROMATIN  ;  see  cell. 

CHROMOSOME;  see  cell. 

CONJUGATION  ;  see  cell. 

CYTOPLASM  ;  see  cell. 

535 


536  THE  LAWS  OF  HEREDITY 

DARWINIAN  ;  a  term  sometimes  used  to  designate  that  school  of  evolutionists  which  denies 
the  transmission  of  acquirements,  and  sometimes  to  designate  the  school  which  supposes 
that  evolution  is  founded,  not  on  mutations,  but  on  fluctuations. 

DAUGHTER-CELL  ;  see  cell. 

DEDUCTION  ;  the  chain  of  reasoning,  the  inverse  process  to  induction,  by  means  of  which  we 
pass  from  a  consideration  of  general  notions  to  a  consideration  of  particular  facts.  It  is 
most  useful  when  employed  to  test  the  correctness  of  inductions  and  bring  within  their 
range  facts  not  previously  included. 

DEVELOPMENT  ;  the  growth  or  unfolding  of  the  individual  from  the  germ. 

EMBRYO  ;  the  individual  in  his  earliest  stages  of  growth  after  development  from  the  ovum. 

ENDEMIC  disease ;  strictly  speaking  a  local  malady  which  has  no  tendency  to  spread. 
Usually,  however,  the  term  implies  the  continuous  presence  of  a  disease  in  a  locality. 

ENZYME  ;  a  ferment  secreted  by  living  cells. 

EPIDEMIC  ;  a  term  applied  to  a  considerable  outburst  or  increase  of  a  disease. 

EVOLUTION  ;  an  adaptive  change  undergone  by  a  race. 

EXCRETION  ;  a  term  applied  both  to  the  act  of  eliminating  waste  or  used  up  material  from 
the  organism  and  to  the  waste  material  itself. 

FERTILIZED  ovum;  see  cell. 
FLUCTUATION  ;  an  unstable  variation. 

FCETUS  ;  the  individual  in  that  stage  of  development  that  intervenes  between  the  embryonic 
condition  and  birth. 

GAMETE  ;  a  germ-cell  before  conjugation. 

GERM-CELL;  see  cell. 

GERM-PLASM  ;  see  cell. 

GERM-TRACT  ;  see  cell. 

GERMINAL  ;  pertaining  to  the  germ-cell,  or  having  origin  in  the  germ-plasm. 

HAEMOPHILIA  ;  a  disease  or  state  in  which  the  blood  lacks  coagulating  power. 
HEREDITY  ;  the  organic  relation  between  progenitors  and  descendants. 
HEREDITARY  tendencies  ;  see  cell. 
HERMAPHRODITE  ;  see  cell. 

HYBRID  ;  an  offspring  or  descendant  derived  from  the  union  of  individuals  belonging  to 
distant  species. 

HYPOTHESIS  ;  an  inference  not  yet  proved  to  be  true. 

INBORN  or  innate ;  a  term  employed  to  designate  characters  which  are  supposed  to  differ 
from  acquirements  in  that  they  are  especially  rooted  in  the  constitution  of  the  individual. 
Really  it  designates  traits  that  develop  under  stimuli  other  than  use  and  injury. 

INDIVIDUAL  ;  see  cell. 

INDUCTION  ;  the  process  of  thought  by  means  of  which  we  found  general  notions  on  a 
consideration  of  particular  facts.  Thus,  having  observed  that  offspring  recapitulate  the 
parental  development,  we  reach  through  induction  the  notion  that  they  recapitulate  the 
life-history  of  the  race. 

INHERITABLE  ;  a  term  used  to  designate  characters  that  arise  under  a  stimulus  other  than 
use  or  injury.  Really  no  characters  are  inheritable,  or  all  are  equally  inheritable. 

LAMARCKIAN  doctrine ;  the  doctrine  that  offspring  tend  to  reproduce  miraculously  under 
the  stimulus  of  nutriment  traits  which  evolution  fitted  progenitors  to  acquire  under  the 
stimulus  of  use  or  injury. 

LARVA  ;  an  insect  in  that  stage  of  development  which  precedes  the  final  stage. 

LAW,  natural ;  an  established  theory ;  a  description  of  a  uniformity  in  the  sequence  of  events 
the  actual  existence  of  which  has  been  proved. 

LIFE-HISTORY  ;  the  stages  of  the  evolution  of  the  race. 

MATERNAL  impression ;  a  term  having  origin  in  the  popular  belief  that  maternal  mental 
impressions  are  apt  to  produce  analogous  physical  peculiarities  in  the  child. 


GLOSSARY  537 

MENDELISM  ;  a  biological  doctrine  founded  by  Mendel. 

MICROBES  ;  unicellular  animals  and  plants  which  cause  infectious  disease  in  higher  tvpes. 

MODIFICATION  ;  a  term  commonly  used  to  designate  a  character  which  has  resulted  from  use 

or  injury  ;  an  acquirement. 

MONGREL  ;  the  offspring  or  descendant  of  parents  that  were  derived  from  distant  varieties. 
MONSTER  ;  an  individual  that  diverges  very  greatly  from  the  type  of  his  race. 
MOTHER-CELL  ;  see  cell. 
MULTICELLULAR  ;  see  cell. 

MUTATION  ;  according  to  de  Vries,  a  wide  departure  from  the  normal  type,  a  '  sport ' ; 
according  to  Punnett  and  others,  a  stable  variation. 

MUTATION  hypothesis ;  the  doctrine  that  evolution  is  founded  on  mutations. 

NUCLEUS  ;  see  cell. 
NUCLEO-PLASM  ;  see  cell. 

OVUM  ;  see  cell. 
OVULE  ;  see  cell. 

PANDEMIC  ;  a  very  wide-spread  epidemic. 

PARASITE  ;  an  organism  that  obtains  its  nutriment  from  the  tissues  of  living  beings. 

PARTHENOGENESIS  ;  see  cell. 

PATHOGENIC  ;  disease-producing. 

PLACENTA  ;  the  organ  which  connects  a  mother  with  her  unborn  child. 

POLLEN-GRAIN;  see  cell. 

PROGRESSION  ;  an  increase,  due  to  variation,  of  one  or  more  of  the  qualities  of  a  character 
— e.g.  size,  complexity,  power. 

PROTOPLASM  ;  the  physical  basis  of  life. 

RECAPITULATION;  the  recapitulation  (always  with  variations)  by  the  individual  of  the 
parental  development  and  the  racial  life-history. 

REGRESSION  ;  the  tendency  displayed  by  the  progenitors  or  descendants  of  exceptional 
individuals  to  be  nearer  the  racial  mean. 

RETROGRESSION  ;  a  decrease,  due  to  variation,  of  one  or  more  of  the  qualities  of  a  character. 
REVERSION  ;  a  return  to  the  ancestral  type. 

SAPROPHYTE  ;  an  organism  that  obtains  its  nutriment  from  non-living  matter. 

SELECTION  ;  is  of  several  kinds ;  artificial,  when  man  consciously  chooses  the  progenitors 
of  a  race :  natural,  when  unconscious  nature  exercises  the  choice ;  reversed,  when  the 
selection  "  affects  not  increase  of  an  organ,  but  decrease  of  it " ;  germinal,  when  (as 
has  been  supposed)  the  selection  occurs  among  the  units  of  the  germ-plasm. 

SELECTIONIST  ;  an  adherent  of  the  doctrine  that  evolution  is  founded  on  the  selection  of 
fluctuations. 

SELF-FERTILIZATION  ;  see  cell. 

SEXUAL  ;  see  cell 

SOMA ;  see  cell. 

SOMATIC  ;  pertaining  to  the  soma. 

SPERM  or  spermatozoa  ;  see  cell. 

SPONTANEOUS  ;  a  term  used  to  designate  alterations  in  the  germ-plasm  caused,  not  by 
external,  but  by  internal  conditions. 

TELEGONY  ;  a  term  having  origin  in  the  popular  belief  that  if  a  mother  has  offspring  by  two 
mates,  the  children  of  the  second  father  will  exhibit  the  influence  of  the  first. 

THEORY  ;  an  inference  or  hypothesis  which  has  been  proved  to  be  true. 
TOXIN  ;  a  poison,  offensive  or  defensive  in  function,  secreted  by  a  living  being. 


538  THE  LAWS  OF  HEREDITY 

UMBILICAL  cord  ;  the  structure  which  passes  from  the  navel  of  the  child  to  the  placenta. 
UNICELLULAR  ;  see  cell. 
UTERUS  ;  the  womb. 

VARIABILITY  ;  the  tendency  to  vary. 

VARIATION  ;  a  filial  departure,  founded  on  a  germinal  change,  from  the  parental  type. 

WASTE-PRODUCTS  ;  the  final  products  of  tissue  metabolism.  They  are  excreted  by  living 
beings,  and  are  comparable  to  the  ash,  carbonic  acid,  water,  etc.,  which  result  from  the 
combustion  of  coal. 

ZYGOTE  ;  the  fertilized  ovum. 


INDEX 


ABILITY,  biometric  investigation  of,  136-7, 
428  et  seq.  ;  nature  of,  421-2 

Abnormalities,  22 

Aborigines,  decay  of,  279 

Abrin,  toleration  of,  247 

Abstinence  from  Alcohol,  ancient,  459 

Acclimatization,  meaning  of  term,  263 

Acquired,  right  use  of  term,  20 

Acquirements,  real  nature  of,  14  et  seq.  ; 
importance  of,  n  et  seq.,  245,  424,  485; 
superiority  to  inborn  traits,  69  et  seq.,  401, 
424 ;  mental,  379,  401 

Actions,  protoplasmic,  371 ;  reflex,  371 ;  instinc- 
tive, 373;  rational,  373  etseq.\  voluntary,  373 
et  seq.  ;  deliberate,  376  ;  automatic,  400 

Adaptation,  universality  of,  21,  56-7,  106, 
182,  187,  206,  219,  236,  324-5,  373,  390-2, 
396 ;  of  microbes,  238  ;  of  the  individual, 
57  ;  test  of,  222  ;  mental,  324,  388  et  seq. 

Adaptability  of  man,  381,  428 

Africa,  West,  malaria  in,  234-5;  alcohol  in, 
299,  302  et  seq. 

Alcohol,  a  waste  product,  243 ;  effect  on 
health,  286-7,  3*7  et  seQ-  '•>  immediate  and 
remote  effects,  306-7;  craving  for,  288  et 
Se1">  457;  variations  in  craving  for,  289 
et  seq.  ;  influence  of  environment  on  con- 
sumption, 292-3  ;  as  agent  of  natural  selec- 
tion, 294  et  seq.  \  artificial  selection  for, 
457-8  ;  evolution  caused  by,  297,  308  et 
seq.,  458 ;  compared  to  tuberculosis,  308  ; 
civilization,  313 ;  climate,  311-2 ;  occupa- 
tion, 314  et  seq.  ;  strength  of  beverages,  313  ; 
ancient  use  of,  299  et  seq. ;  laws  prohibit- 
ing use  of,  300,  306,  458  et  seq.  ;  average 
racial  consumption  of,  311 ;  convivial  and 
industrial  drinking,  314  et  seq.  ;  suscepti- 
bility to  charm  of,  289,  293-4 ;  susceptibility 
not  a  disease,  457 ;  alleged  cause  of  racial 
deterioration,  322 ;  antiquity  of  drinking. 
299  ;  drinking  of  Jews,  299,  301-2  ;  Greeks, 
300 ;  Italians,  301 ;  West  Africans,  302-3 ; 
Germans,  304-5 ;  British,  305 ;  Chinese, 
305-6  ;  savages,  306  ;  Mohammedans,  460 

Alcoholism,  and  disease,  457 ;  chronic,  318 ; 
altruistic,  318  et  seq. ;  impossibility  of  pre- 
venting, 457,  465 

Alison,  on  drinking  of  savages,  306 

Allelomorphs,  155 ;  compound,  161 ;  non- 
existence  of,  1 88 

Alternation,  of  generations,  23  ;  of  progres- 
sion and  retrogression,  25  ;  of  sexual  traits, 
190 

Alternative  reproduction,  conditions  of,  178 

Anatomy,  systematic,  33,  504 

Ancestral  Inheritance,  Law  of,  126  et  seq. 

resemblances,  523 


Andalusian  Fowls,  155 

Ani,  maxims  of,  300 

Animals,  lower,  minds  of,  380,  398,  415,  425  ; 

dreams  of,  418  ;  social,  382 
Ant,  mental  operations  of,  382-3;  brains  of, 

405 

Anthrax,  lethal  dose  of  for  rabbit,  86 ;  attenua- 
tion of,  240 
Antitoxin,  preparation  of,  240;  mixed  with 

toxin,  241,  243-4 
Aphides,   latency  of  male  characters,   113 ; 

variability    of,    148 ;    cause    of  disease    in 

vines,  276 

Aptitudes,  mental,  422 
Areopagus,  laws  against  drinking,  300 
Aristophanes,  on  drinking,  300 
Arsenic,  toleration  of,  247 
Astronomy,  scientific  method  in,  503 
Athens,  great  men  in,  496 
Attention,  area  of,  412-3 ;  concentration  and 

diffusion  of,  413-4 ;    association  with  the 

will,  414 

Attractions,  sexual,  145,  189 
Australia,  temperancealegislation  in,  462,  464 
Automatic  actions,  400  et  seq.  ;  compared  to 

reflexes,  410-1 ;  characteristics  of,  411-12 
Automaton  hypothesis,  356  et  se.q 
Axioms,  mathematical,  346 


BACON,    Francis,   on  the  power  of  words, 
19-20 ;    service  to  science,   50 ;    on  know- 
ledge by  causes,  343 
Bacot,  Mr  A.,  on  repertoire  patterns,  60 
Baldwin,  Prof.  Mark,  on  use-acquirements, 

72  ;  on  plasticity,  408 
Bantam,  Sebright,  146,  165,  189 
Baring,  Mr  Maurice,  on  drinking  in  Russia, 

320 

Bateson,  Mr  W.,  on  dandelions  and  hawk- 
weeds,  148 ;  on  segregation,  153,  154 ;  on 
central  doctrine  of   Mendelism,    154 ;   on 
imperfect  dominance,    155 ;  on  compound 
allelomorphs,  161 ;  on  discontinuous  origin 
of  Mendelian  characters,  162  ;  on  ferments, 
164;  on  limitations  experimentation,  172; 
on   scientific  method,    184-5 ;    on  fertility 
and  Mendelian  inheritance,  190 ;  on  Men- 
delian inheritance  of  sexual  characters,  191 ; 
on  inheritance  of  stature,  193 ;  on  systema- 
tists,  506  ;  on  origin  of  species,  506 
•  Bathmic  hypothesis,  60 
I  Beauty,  appreciation  of,  423-4 
j  Bees,  latency  of  male  characters,  113  ;  diseases 

of,  275 

Berberis  vulgaris,  repertoire  patterns  of,  60 
i  Berkeley,  on  Idealism,  334 
'  Bible,  exhortations  against  intemperance,  299 

539 


540 


THE  LAWS  OF  HEREDITY 


Biologists,  as  essayists,  184-5 ;  contrasted 
with  students  of  other  sciences,  509-10 ; 
education  of,  510  et  seq. 

Biometry,  36,  133  et  seq.,  226,  261,  409,  428 
et  seq.,  443,  447,  509;  wasted  labours  of, 
136  et  seq. 

Black  Death,  the,  271-2 

Blending,  abnormal,  of  sexual  traits,  146 ; 
normal,  195;  of  Mendelian  traits  1 60- 1,  196; 
of  crossed  human  races,  173-4 ;  of  fluctua- 
tions, 189 ;  meaning  of  term,  194-5 ;  the 
only  exception  to,  195;  of  mutations,  196  ; 
effects  of,  197 

Bosanquet,  Dr  W.  C. ,  on  immunity,  238  ;  on 
virulence,  238 

Botany,    systematic,    33,    504;    method    of, 

39.  5°4 

Brain,  relation  to  mind,  362  et  seq.  ;  evolu- 
tion of,  396-7 ;  relation  of  size  to  intelli- 
gence, 434-5 

Branthwaite,  Dr,  on  alcoholism  and  feeble- 
mindedness, 316 

British,  the,  intemperance  of,  305 ;  alleged 
mental  deterioration  of,  430 

British  Medical  Association,  investigation  on 
alcoholism,  295-6 

Brown-Se"quard,  on  transmission  of  acquire- 
ments, 73 

Bum  pus,  on  Natural  Selection,  136 

Bushmen  of  New  Zealand,  drinking  habits 
of,  288 


CANADA,  temperance  legislation  in,  462 
Canaries,  varietal  crossings  of,  156 
Cancer,  103 
Capacity,  for  growth,  6  ;  mental,  421  et  seq.  \ 

variations  in,  425  ;  definition  of,  438 
Carnivora,  immunity  to  septic  poisoning,  89 
Casas,  las,  Bishop,  philanthropic  efforts,  280 
Castle,  Prof.  W.  E. ,  on  dominance,  157 ;  on 
gametic  purity,    161  ;  on   mutation  hypo- 
thesis,  170;  on  Mendelian  inheritance  of 
sexual  traits,  191 

Caterpillar,  development  of,  120;  instincts 
°fi  3?6-7i  379 ;  lack  of  memory,  379,  422  ; 
mental  growth  of,  421 

Catholics,  Roman,  mental  traits  of,  427,  495 
Causation,  chain  of,  47-8,  349 ;  circle  of,  350 
Cause  and  effect,  343,  350 
Cells,    in  uni-  and  multicellular  organisms, 
i  ;     multiplication    of,  i ;     daughter-,     i  ; 
specialization  of,  i ;   contractility  of,   and 
mind,  368-70 
Cell-community,  i 
Cephalic  index,  429 

Cerebrum,  association  with  memory,  396 
Chapters  in  development,  missing,  27 
Characters,  relation  to  germ-plasm,  8  ;  inborn 
and  acquired,  15-16  ;  changes  during  evolu- 
tion, 118  ;  non-adaptive,  219,  391-2 
Chauveau,  Prof.,  on  immunity,  243 
Chemistry,  study  of  compared  with   that   ot 

biology,  31,  34,  5°4 
Chicken-pox,  deaths  due  to,  260 ;  compared 

to  tobacco,  308 

Child,  mental  peculiarities  of,  394  ;  education 
of,  480 ;  effects  of  religious  training  on, 
487 


Chinese,  drunkenness  among,  306  ;  brains  of, 

Chloroform,  craving  for,  289 
Chromatin,  as  bearer  of  heredity,  3 
Chromosomes,  numbers  of,  131 
Civilization,    effects    of,    222     et   seq.;     and 

disease,  269  et  seq. ,  278  ;  and  alcohol,  298  ; 

and  prohibition,  459  et  seq. 
Civilized  man,  distinction  from  savage,  397 
Classical,  teaching,  501 
Classification  of  facts,  36  et  seq.;  of  feelings, 

Clayton,  experiments  on  beans,  84,  97 
Clifford,  on  science,  37  ;    on    idealism,  335 ; 

on  relation  of  mind  to  body,  357 
Climates,  healthy  and  unhealthy,  263  ;    and 

intemperance,  311 

Cocaine,  use  as  substitute  for  alcohol,  463 
Cochin  fowl,  155 
Cockburn,  Sir  J.,  on  intelligence  of  Australian 

Blacks,  469 

Coherence  of  thought,  329  et  seq.,  340 
Colour-blindness,  inheritance  of,  189 
Columbus,  voyage  of,  278 
Committee  of  Fifty,  investigation  by,  463 
Common  sense,  definition  of,  324 
Conception,  mental,  326 
Confidence  trick  in  science,  510 
Conjugation,  not  a  necessary  antecedent   of 

reproduction,  2,  142  ;  effects  of,  144,  188 ; 

function  of,  202 

Contributions,  ancestral,  126  et  seq. 
Controversy,  utility  of,  45 
Cope,  Prof.,  on  evolution,  n 
Correlation,  70-1,  182,  261 ;  between  size  of 

brain  and  mental  capacity,  434 
Cowpox,  238 
Crabs,  changes  of  sex,  114;  blind,  123 ;  lack 

of  memory  in,  407 
Crawley,  Rev.  A.  G. ,  on  religion  of  savages, 

488 
Crichton-Browne,  Sir  J.,  on  mental  defects, 

468 

Crime,  causation  of,  494 
Criteria,  for  facts  and  thinking,  32,  505-6,  512 
Crucial  instances,  165 
Cuba,  imported  disease,  280 
Cue"not,  Prof.,  theory  of  factors  and   deter- 
miners, 164,  166 

Curiosity,  instinct  of,  385  ;  in  education,  478-9 
Cypris  reptans,  stability  of,  201 

D 

DANDELIONS,  parthenogenesis  in,  148 

Darbishire,  Mr  A.  D.,  experiments  on  mice, 
163 

Darien,  British  colony  in,  235 

Dark  Ages,  diseases  in,  269 ;  mental  training 
in,  497 

Darwin,  Charles,  hypothesis  of  pangenesis, 
5,  66  ;  belief  in  the  transmission  of  acquire- 
ments, 61  ;  on  retrogression,  112 ;  on 
latency,  113-4,  165,  177  ;  belief  in  blended 
inheritance,  150  ;  on  reversion  in  pure-bred 
races,  165-6 ;  on  artificial  selection,  176  ; 
method  of  work,  185,  214-5  ;  on  effects  of 
crossing,  198  ;  use  of  deduction  by,  212-3, 
346 ;  his  teaching,  212,  391,  505 ;  on 
memory,  405  ;  the  Newton  of  biology,  506 


INDEX 


541 


Darwin,  Mr  Francis,  on  the  transmission  of 
acquirements,  74 

Daughter-cells,  i 

Davenport,  Prof.  C.  B.,  on  Mendelian  traits 
of  poultry,  155,  172 ;  on  blending  of 
Mendelian  traits,  160-1 

Deaf-mutism,  inheritance  of,  189 

Death  certificates,  295 

Deduction,  nature  of,  42-3  ;  function  of,  46, 
51-2;  medical  condemnation  of,  30,  211, 
509  ;  in  physics,  47,  49,  211,  214-5,  5°3  >  m 
mathematics,  47,  211,  344,  355,  503,  505, 
509  ;  in  biology,  49-50,  345,  509  ;  Darwin's 
use  of,  212-3  ;  when  necessary,  509 

Deductions,  from  fact  of  immunity,  257-8 

Dendy,  Miss,  on  fertility  of  the  feeble-minded, 

475 

Desire,  emotion  of,  373-4 

Deterioration,  physical,  446  et  seq. ;  cure  of,  449 

Determinants,  109 

Determiners,  164 

Development,  method  of,  23 ;  of  human 
beings,  26-6  ;  periods  of  slow  and  rapid, 
120-1  ;  independent,  154,  160. 

Devotion,  to  truth,  41 ;  to  beliefs,  488 

Devotional  faculty,  325 

Dexterities,  physical  and  mental,  419 

Diets,  human,  440 

Digitalis,  hybrids  of,  157 

Dimorphism,  sexual,  142,  144,  188-9 

Diphtheria,  antitoxic  treatment  of,  240,  248  ; 
effects  of  sanitation  on,  450 

Discrimination,  377 

Diseases,  regarded  as  experiments,  39-40, 
216,  261 ;  evidence  furnished  by,  against 
mutation  hypothesis,  199;  in  England, 
224 ;  selection  by,  225 ;  list  of  microbic, 
227 ;  frequency  of,  227 ;  air-borne,  228, 
239,  272,  278,  451-3 ;  contagious,  229, 
270,  450-1 ;  earth-borne,  229,  274-5,  453  ; 
insect-borne,  229,  271-2,  451 ;  water-borne, 
228,  274,  451  ;  general,  230,  239 ;  cause  of 
duration,  233-4 ;  spread  of,  236 ;  epidemic 
and  endemic,  257,  275,  277,  279,  452 ;  as 
material  for  study  of  heredity,  261 ;  resist- 
ance of  human  races  to,  263,  of  lower 
animals,  275-6 ;  evolution  of,  266  et  seq.  • 
extinction  of,  268  ;  places  of  origin,  269  ; 
migration  of,  270-1 ;  antiquity  of,  269,  275  ; 
conditions  of  prevalence,  275 ;  invasion  of 
Western  Hemisphere,  278^^.;  as  empire- 
builders,  281  et  seq. 

Disuse,  as  criterion  of  nature  of  growth,  7 ; 
alleged  as  cause  of  retrogression,  108 

Dogs,  deterioration  in  India,  84,  98 ;  dis- 
temper of,  275  ;  crossing  of  large  and  small 
breeds,  198 

Dominance,  153 ;  imperfect,  155;  of  recessive 
characters,  155  ;  influenced  by  sex,  156 ;  by 
environment,  156  ;  by  race,  157  ;  by  idio- 
syncrasy, 157  ;  a  phenomenon  of  sexual  re- 
production, 192 

Dominants,  pure,  impure,  and  extracted,  153, 
!58 

Donkin,  Dr  H.  B.,  on  cirrhosis  of  liver,  295 

Dow,  General  Neal,  on  prohibition  in 
Maine,  463-4 

Dreams,  416  et  seq. 

Drelincourt,  on  speculations  about  sex,  199 

Drift  racial,  caused  by  environment,  92 


Drinkers,  the  three  classes  of,  285,  286 
Dyer,   Sir    W.   Thiselton,   on  latency  in    a 
natural  species,  176  ;  method  of  work,  185 


EARTH,  shape  of,  489  et  seq. 

Education,  and  alcohol,  312  ;  importance  of, 
477;  in  early  life,  478-9;  in  school-room, 
479-80 ;  of  young  adults,  481  et  seq. 

Educability,  398,  428 

Efficiency,  422 

Egypt,  disease  in,  269 ;  intemperance  in,  300, 
459 

Ehrlich,  hypothesis  of  immunity,  251  et  seq. 

Embryo,  prototypes  of,  27 ;  adaptations  of, 
119 

Emotions,  acquired,  410 

Enumeration,  simple,  54,  342-3,  509 

Epidemic  and  endemic  diseases,  272,  452 

Error,  sources  of,  36 

Esquimaux,  effects  of  vaccination  on,  239 

Essayists  in  biology  184-5 

Europe,  use  of  alcohol  in,  299 

Evidence,  when  admissible,  35 ;  neglect  of, 
59.  136 

Evolution,  universal  belief  in,  4;  recapitula- 
tion of,  24 ;  theories  of,  59-62,  258 ;  of 
toxins,  88  et  seq.  ;  of  human  races,  180 ; 
against  disease,  224-5  •  against  alcohol,  297 

Ewart,  Prof.  J.  Cossar,  on  causation  of  varia- 
tions, 81-2,  85  ;  on  retrogression,  112 ;  on 
horse-zebra  hybrid,  156 

Exact  methods  of  inquiry,  34  etseq.  \  sciences, 

36,  211 

Exclusive  inheritance,  151 

Exodus,  book  of,  on  leprosy,  269 

Experience,  stored  in  mind,  377 

Experiment,  object  of,  33  ;  two  ways  of  using, 
43;  scope  in  biology,  45,  50,  51,  510; 
failure  of,  44-5,  81-5,  87-91,  98-9,  171-3,  184, 
204-5,  22I>  264,  409;  as  cause  of  contro- 
versy, 45 

Experimental,  sciences,  36,  502 ;  evidence  in 
favour  of  Lamarckian  doctrine,  73  ;  school, 
30-1,  184 

Explanation,  nature  of,  349 

Extracted  dominants  and  recessives,  158 

Eye-colour,  reproduction  of,  145-6,  149,  174, 
178,  428  et  seq. 

Eyes,  retrogression  of,  123,  223 ;  protected  and 
unprotected,  418 


FACTS,  admissible,  32 ;  patent  and  obscured, 
33 ;  scientific  value  of,  38,  480  ;  teaching  of, 
480 

Factors,  colour-,  164 

Faith,  488 

Family  life,  380 

Fashion,  influence  of,  204,  292,  386 

Feeble-mindedness,  425,  465^^^. 

Female  characters,  reproduced  by  male,  114 

Fe"re",  on  alcoholized  eggs,  264 

Fertility,  biometric  investigation  of,  137-8, 
430-1 ;  evolution  of,  137-8 ;  of  the  insane, 
475 

Fertilization,  not  essential  condition  of  repro- 
duction, 2,  142 


542 


THE  LAWS  OF  HEREDITY 


Filial  regression,  law  of,  134 

Fluctuations,  150,  506  ;  blending  of,  176 ;  as 

causes  of  racial  change,  179,  183-4 
Food-supply,  269 ;  in  manufacture  of  alcohol, 

298 

Fovea  centralis  of  eye,  412  ;  of  attention,  413 
Fowler,  I. ,  on  knowledge  by  causes,  54 
Fowls,  Mendelian  traits  of,  155, 156,  157,  160, 

165,  167,  172 
Frog,  instincts  of,  381 
Froude,  on  disease  in  West  Indies,  280 
Fry,  Sir  J.,  on  increase  of  insanity,  471-2 
Function,  of  cells,  i ;  of  sex,  197 ;  definition 

of  term,  188 


G ALTON,  Sir  F.,  on  Law  of  Ancestral  Inheri- 
tance, 126  et  seq.  ;  on  kinds  of  inheritance, 

151 

Gamete,  153 

Gametic  purity,  157 

Garden  plants,  variability  of,  100 

Gartner,  on  latent  characters,  176 

Genetics,  new  science  of,  188 

Geniality,  429 

Genius,  426 

Geology,  systematic,  33 

Geometry,  343,  347.  480,  503 

Germans,  ancient  drinking  customs,  304-5 

Germ-cells,  2 ;  potential  immortality  of,  5 ; 
cause  of  numbers  of,  96 ;  alleged  in- 
violability of,  264 

Germ-plasm,  nature  of,  3 ;  continuity  of,  5, 
124,  134 ;  quantitative  and  qualitative 
division  of,  17-8 ;  necessity  of  thinking  in 
terms  of,  15,  25  ;  causation  of  variations  in, 
80  et  seq.  ;  resistance  to  direct  action  of 
environment,  92  et  seq.  ;  as  living  entity,  98 

Germinal  selection,  109  ;  changes,  221-2 

Gibbon,  on  drinking  customs  of  Ancient 
Germans,  304 

Gilbey,  Sir  A.,  on  race-horses,  in 

Gordon,  Dr  H.  Laing,  on  drinking  in  Italy, 
301 

Gout,  transmission  of,  74 

Gravitation,  law  of,  47,  352,  360 

Greece,  drinking  in,  300 ;  teaching  in,  490-1 

Growth,  factors  of,  6,  422,  438  ;  of  mind  and 
body  compared,  420,  477 

Growth-force,  60 

Guinea-pigs,    susceptibility    to    tuberculosis, 

255 
Gulick,  Rev.  J.  T.,  on  snails,  202 

H 

HABITS,  401  et  seq.  ;  483,  515 
Habituation  to  toxins,  247,  253 
Haemophilia,  alleged  transmission  of,  75 
Hair-colour,  145,  428 
Hair-texture,  174-5 
Ha.lter^d^^tm,  81 
Hapsburgh  lip,  181 
Hare,  Dr  F.,  on  deduction,  30 
Hartog,  Prof.  M.,  on  transmission  of  acquire- 
ments, 74 

Harveian  Society,  on  alcoholism,  295 
Hawkweeds,  parthenogenesis  in,  148" 
Heart's-ease,  evolution  of  pansy  from,  112 


Henslow,  Prof.  G.,  on  transmission  of 
acquirements,  74 

Hereditary  tendencies,  definition  of,  3  ;  altera- 
tion of,  79 

Heredity,  material  for  study  of,  34 ;  not  an 
exact  science,  35-6  ;  experimental  study  of, 
34  et  seq.,  184,  510;  greater  problems  of, 
216-7 

Hermaphrodite,  143,  146 ;  human,  146 

Herschell,  on  science,  37 

Hewitt,  on  variations  in  ducks,  83;  on  rever- 
sion in  bantams,  165 

Hinny,  157 

Hipparion,  hoofs  of,  123 

Hipprtris,  60 

History,  life-,  24 

Historians,  on  disease,  276-7 

Hodgson,  Dr,  on  Idealism,  336 

Hoffmann,  experiments  on  plants,  83 

Homer,  on  drinking,  300 

Horse,  retrogression  in,  123 ;  American  trot- 
ting, 179  ;  latent  traits  in,  196 

Human  beings,  mutations  of,  175,  179  ;  racial 
differentiation,  180-1 ;  racial  crossings,  173 
et  seq.,  200-1 ;  as  subjects  for  study,  216, 
220-1 ;  errors  about  racial  changes  of,  223  ; 
lack  of  instinctive  movements,  378-9 ;  distin- 
guishing peculiarity,  424 ;  adaptability, 
381,  428;  ways  of  improving,  438-9;  arti- 
ficial selection  of,  439 

Hume,  on  mind,  335 

Hunger,  instinct  of,  384 

Hunter,  Dr  W.,  on  maternal  impressions,  75 

Hurst,  Mr  C.  C.,  experiments  on  poultry, 
156  ;  on  rabbits,  163 

Huxley,  method  of  work,  185 ;  on  necessary 
truth,  349 ;  on  science,  351 ;  on  relation  of 
mind  to  body,  356-7  ;  on  curates,  478 

Huxley  lecture,  428 

Hybridization,  almost  confined  to  artificial 
varieties,  176 

Hydroidce^  27 

Hypotheses,  39-40 ;  untested,  49-50 ;  of 
chemists  and  physicists,  50 ;  bathmic,  60  ; 
nature  of,  512 


IDEALISM,  definition  of,  324 ;  thorough  going, 
333  ;  futility  of,  334,  336,  338,  360 

Idiot,  mind  of,  389,  425,  465  et  seq. 

Imagination,  the  scientific,  52,  89 

Imbecility,  53  ;  as  variation,  425  ;  nature,  425, 
465  ;  in  slums,  447  ;  causation,  472-3  ;  pre- 
vention, 475 

Imitativeness,  385 

Immunity,  inborn  and  acquired,  233,  235,  253, 
254>  257 1  conditions  of,  237,  248 ;  active 
and  passive,  241 ;  Pasteur's  hypothesis 
243 ;  Cheauveau's,  243 ;  Behring's,  243  et 
seq. ;  Ehrlich's,  251  et  seq. ;  in  acute  and 
chronic  disease,  257 ;  inference  of  conse- 
quences from,  258-9 ;  evolution  of,  225  ; 
meaning  of  term,  309 ;  artificially  de- 
veloped or  evolved,  450,  453,  455 

Impure  dominants,  153 

Inborn  and  acquired  characters,  true  distinc- 
tion between,  16-7 ;  general  failure  to  dis- 
tinguish between,  439-40 


INDEX 


543 


Individual,  derivation  from  ovum,  5-6 

Induction,  nature  of,  42 

Inertia,  mental,  493 

Insanity,  the  two  kinds,  465 ;  increase  of, 
471 ;  causation  of,  472-3 

Instinct,  definition  of,  374;  human,  374-5, 
383;  imitated  by  acquirements,  400-1, 
410;  extended  by  acquirements,  422;  dis- 
tinguished from  acquirements,  423  ;  modi- 
fied by  acquirements,  423-4  ;  for  food,  440 ; 
to  think,  403,  478 

Intelligence,  and  fertility,  138,  478 ;  defined, 
377 ;  measure  of,  378  ;  distinguished  from 
reason,  378  ;  substituted  for  instinct,  380 
et  seq.  ;  adaptiveness  of,  398,  478  ;  Pearson 
on,  431 ;  relation  to  size  of  brain,  434 ;  of 
adult  compared  with  that  of  child,  491 

Isolation,  physiological,  143,  178,  181 

Italy,  drinking  in,  300-1 


JAMES,  Prof.  W.,  on  science,  351,  360;  on 
Idealism,  336 ;  on  separateness  of  mind 
and  body,  361 ;  on  memory,  395 

Japan,  social  and  intellectual  changes  in, 
445,  497  ;  tuberculosis  in,  454 

Jealousy,  instinct  of,  424 

Jennings,  Mr  H.  S.,  on  paramoecium,  94 

Jevons,  on  framing  of  hypotheses,  42  ;  on  the 
Newtonian  method,  52 

Jews,  ancient  intemperance  of,  299;  modern 
sobriety,  301 ;  mental  peculiarities  of,  428  ; 
effects  of  urban  life  on,  448 


K 


KANT,  on  mind,  335 

Kemp,  Rev.  D.,  on  drinking  in  West  Africa, 

3°3-4 

Kepler,  on  planetary  motion,  43,  48 
Kindergarten  system,  481 
Kingsley,   Miss  M.,   on    malaria,    235;    on 

drinking  in  West  Africa,  303 
Knowledge,  sources  of,  338  ;  traditional,  381 ; 

useful,  478 


LABOUR,  479 ;  laborious  mental  training,  479 
Laboratory  methods,  when   useful,  33,   35  ; 

scope  in  physics  and  biology,  49 
Lake  dwellers,  use  of  alcohol  by,  299 
Lamarckian  hypothesis  of  evolution,  n,  61, 
62,  76 ;   controversy,   15-6 ;   strongest  evi- 
dence against,  73  ;  applied  to  disease,  259 
Landois  and  Stirling,  on  ciliary  action,  369 
Lankester,  Sir  E.  Ray,  on  retrogression,  22; 
method  of  work,  185  ;  on  alcohol,  297 ;  on 
size  of  brain  and  intelligence,  434 ;  on  im- 
beciles, 469-70 

Latency,  distinguished  from  retrogression, 
113,  115;  temporary,  113;  permanent,  114; 
of  sexual  traits,  145,  159,  195  ;  of  Mendelian 
traits,  160  et  seq.  ;  of  eye-colour,  174 ;  Dar- 
win on,  177  ;  de  Vries  on,  177  ;  occurs  only  in 
artificial  varieties,  176 


Latent  characters,  alternation  of,  115-6; 
common  in  artificial  varieties,  161  et  seq.  ; 
absent  in  natural  varieties,  275  et  seq. 

Law,  natural,  definition  of,  47,  348 ;  of 
Ancestral  Inheritance,  126  et  seq.  ;  of  filial 
regression,  134 ;  laws  of  heredity,  213 

Laws,  against  excessive  drinking,  300,  305, 
306,  458  et  seq.,  465 

Leprosy,  antiquity  of,  269 

Lewes,  idea  of  evolution,  n  ;  on  intelligence, 
406 

Life  insurance  and  alcohol,  287,  296 

Linnaeus,  scientific  method,  511 

Lobster,  lack  of  memory,  407 

Local  option,  462,  464 

Lock,  Mr  R.  H.,  on  experiment,  31 ;  mulat- 
tos, 174  ;  on  study  of  human  species,  180  ; 
on  claims  of  Mendelians,  188 

Locomotion,  power  of,  effects  on  number  of 
varieties,  202 

Logic,  Port  Royal,  42 

Love,  sexual  and  parental,  386 

Lubbock,  on  wasps,  418 

Lunacy,  466  et  seq. ,  471 

Lycurgus,  punishment  of  drinkers  by,  300 


M 


MACAULAY,  on  scientific  method,  42 

M'Gregor,  Sir  W.,  on  drinking  in  West 
Africa,  302 

Mach,  on  scientific  facts,  47 

Macpherson,  Dr  J.,  on  increase  of  insanity, 
47i 

Malaria,  in  pigeons,  81 ;  an  insect-borne 
disease,  229 ;  duration  of,  234 ;  racial  re- 
sistance to,  235,  309  ;  migrations  of,  271 ; 
evolution  against,  309 

Male  characters,  alternation  with  female 
traits,  145  et  seq. ;  reproduced  by  female, 
113.  165 

Man,  crossed  races  of,  173  et  seq. ;  neglect  of, 
by  biologists,  216,  218 ;  place  of  origin,  269  ; 
helplessness  at  birth,  381 ;  differences  be- 
tween savage  and  civilized,  ancient  and 
modern,  397 ;  distinction  from  lower  ani- 
mals, 404;  mental  differences  between 
individuals,  426  et  seq. 

Manipulation,  association  with  brain,  396 

Maoris,  mental  traits  of,  398  ;  social  state, 
427  ;  and  alcohol,  464 

Maspero,  on  intemperance  in  Ancient  Egypt, 
300 

Maternal,  impressions,  75,  76 ;  love,  378,  386 

Mathematics,  not  an  experimental  science, 
36  ;  method  of,  343  et  seq.,  503,  509,  517 

Mathematical  knowledge,  factors  of,  422 

Matter,  meaning  of  term,  324,  354;  in 
motion,  362 

Mauritius,  invasion  of  malaria,  271 

Medical  men,  and  deduction,  30,  509 ;  Royal 
Commission  on,  74 ;  belief  in  Lamarc- 
kianism,  75,  255,  443 ;  belief  in  direct 
action  of  environment  on  germ-plasm,  81, 
84,  264,  448 ;  on  Jewish  mothers,  448  ; 
evidence  before  Royal  Commissions,  474  ; 
study  of  heredity,  74 

Medical  statistics,  81,  84,  264;  certificates  of 
death,  295  ;  education,  482 


544 


THE  LAWS  OF  HEREDITY 


Memories,  concentrated,  396 

Memory,  importance  of,  325,  330,  338,  377, 
380 ;  defined,  377,  379,  394,  478  ;  evolution 
of,  380,  394,  405 ;  neglected  study  of,  3895; 
superiority  in  youth,  394;  systems  for  im- 
proving, 395  ;  organ  of,  396 ;  conscious  and 
unconscious,  399 ;  range  of,  404  ;  variations 
of,  404,  422 ;  in  Crustacea,  407 ;  in  wasps, 
418  ;  abolished  in  dreams,  416 ;  bearing  in 
mind,  418  ;  distinguished  from  "memories," 
421  ;fdefective  in  the  feeble-minded,  425,465 ; 
instinct  to  play  with  contents  of,  403,  478 

Mendel,  experiments  on  peas,  152,  158 

Mendelian  hypothesis,  chief  points  of,  154- 
158 ;  exceptions  to,  159 ;  central  doctrine 
of,  154 ;  disproof  of,  160  et  seq.  ;  propor- 
tions, 153,  158,  167 ;  exceptions  to  propor- 
tion, 158;  inheritance,  right  interpretation 
of,  163,  165,  167  ;  inheritance  of  mutations, 
169 ;  traits  of  poultry,  172 ;  of  peas,  153  ; 
sexual  and  Mendelian  traits  compared, 
189-91 ;  Mendelian  inheritance  a  human 
creation,  192 ;  deductive  inference  of  con- 
sequences, 193 

Mendelism,  not  tested  by  experiment,  184 ; 
concerned  only  with  problems  of  sex,  188  ; 
and  disease,  280 ;  and  science,  510 

Mental  traits,  co-adaptation  of,  388  et  seq. 

training,  importance  of,  435 ;  of  child, 

401,  478  ;  of  young  adults,  481  et  seq. 

Mercier,  Dr  C. ,  on  transmission  of  acquire- 
ments, 74;  on  craving  for  alcohol,  290; 
on  separateness  of  mind  and  body,  361 

Method,  of  development,  22,  24  ;  of  science, 
42,  185,345,  3Si,  tf&etseq. 

Methods,  exact,  34,  35,  184;  experimental 
and  biometric,  140 

Metzger,  experiments  on  maize,  83 

Mice,  crossed  varieties  of,  162,  163 

Microbes,  variations  of,  87  et  seq.  ;  cause  of 
disease,  227 ;  evolution  of,  88,  266 ;  our 
power  of  banishing,  450 

Microbic  diseases,  effects  of  sanitation,  450 

Middle  Ages,  physicians  of,  269  ;  social  state 
of,  497 

Migrations  of  negroes,  265  ;  of  human  races, 
181,  270  ;  of  disease,  270  etseq. 

Mill,  John  Stuart,  on  deductive  method,  48, 
213-5,  502,  514 ;  on  the  statistical  method, 
140  ;  on  matter,  335  ;  on  knowledge,  343  ; 
on  the  use  of  hypotheses,  512 ;  on  con- 
troversy, 512-3 

Millais,  Sir  E.,  on  breeding  of  Basset  hounds, 
126 

Millardet,  on  false  hybrids,  159 

Mind,  uniqueness  of,  325  ;  alleged  super- 
natural origin  of,  325  ;  not  comparable  with 
matter,  327  et  seq.  ;  growth  of  in  infant, 
329  et  seq.  ;  relation  to  body,  362  ;  the  work 
of  the  brain,  362 ;  relation  to  expenditure 
of  energy,  363-4  ;  evolution  of,  364  ;  a  pro- 
duct of  evolution,  369 ;  but  not  a  direct 
product,  365 ;  association  with  nervous 
tissue,  367  ;  utility  of,  367  ;  beginnings  of, 
368-9,  378,  393 ;  a  product  of  Natural 
Selection,  368 ;  alleged  universal  presence 
of,  368  ;  order  of  evolution,  370,  387,  393, 
409;  of  man,  374  et  seq.,  377,  426,  444  et 
seq.  ;  bearing  in  mind,  418  ;  development 
of,  419 ;  growth  compared  with  that  of 


body,  420,  426;  effects  of  training  on, 
444 

Minds,  of  other  people,  333  et  seq.  ;  closed 
and  open,  492  et  seq. 

Miracle,  59,  65,  90,  325 

Missionaries  and  disease,  280 ;  and  alcohol, 
302  et  seq. 

Mitchell,  Sir  A.,  on  dreams,  417 

Modesty,  423 

Modifications,  15,  21 ;  distinguished  from 
variations,  79 

Mohammedans  and  alcohol,  460 

Monks,  cranial  capacity  of,  435 

Morality,  423  ;  effects  on  of  temperance  legis- 
lation, 462  ;  of  imbeciles,  466 

Morgan,  Prof.  Lloyd,  on  use  acquirements, 
72  ;  on  plasticity,  408 

Prof.  T.  H.,  on  experimentation,  30-1  ; 

on  latency  of  Mendelian  traits,  160;  on 
evolution  and  adaptation,  391 

Morocco,  social  state  of,  497 

Morrison,  Rev.  W.  D.,  on  crime,  495 

Mosaic  inheritance,  155 

Mothers,  Jewish,  448 

Mulatto,  skin  colour,  174 

Mule,  157 

Multicellular  organisms,  i 

Murray,  David  Christie,  on  crime,  494 

Mutilations,  alleged  transition  of,  75 

Mutation,  meaning  of  term,  170 

Mutations,  22,  151  ;  alleged  stability  of,  150, 
169-70,  171,  179,  183 ;  human,  175,  179, 
181 ;  in  wild  nature,  179;  of  O.  lamarckiana, 
179  ;  inutility  of,  179 ;  reproduced  in  the 
mode  of  sexual  traits,  189  et  seq.  ;  blending 
of,  195-6  ;  retrogression  of,  171,  196 

Mutation  hypothesis,  150,  169  ;  grounds  for 
maintaining,  175-6  ;  grounds  for  rejecting, 
181  et  seq. ,  199  ;  not  tested  by  experiment, 
184  ;  inference  of  consequences  from,  194  ; 
and  reflexes,  373 ;  and  mind,  388 ;  and 
palaeontology,  392 

Mutationists  and  biometricians,  150 


N 


NAMES,  importance  of,  18 

Narcissus,   from  cross  between  jonquil  and 

daffodil,  156 

Narcotics,  immediate  and  remote  effects,  306 
Natural   Selection,   theory,   contrasted    with 

Lamarckian  hypothesis,  66  et  seq.  ;  objec- 
tions to,  107,  185,  391 
Natural  varieties,  blending  of  when  crossed, 

176  ;  lack  of  latent  traits,  176 
Nature  and  Nurture,  421,  429 
Naudin,  on  crossed  artificial  varieties,  177 
Necessary  truth,  47,  346,  349 
Negro,  teeth  of,  224  ;  and  malaria,  234  ;  and 

alcohol,  302  et  seq.  ;  migrations  of,  265 
Nervous  tissue,  association  with  mind,  367 ; 

evolution  of,  370 
Neutralization  of  toxins,  hypothesis  of,  243 

et  seq. 
New  Zealand,  aborigines  of,  427  ;  temperance 

legislation  in,  464 
Newton,   on  orbit   of  moon,   43 ;    scientific 

method,  52  ;  on  gravitation,  352 ;  compared 

with  Darwin,  505-6 


INDEX 


545 


Nicotine,  a  toxin,  243,  307 

Nucleus,  of  cell,  the  bearer  of  heredity,  3 

Nutriment,   as  material  for  growth,   6 ;    as 

stimulus,    7;    and    inborn    traits,    14-16; 

alleged  cause  of  variations,  99 


OBSCURED  facts,  33 

Offspring,  relation  to  parent,  5 

Old  age,  mind  in,  421 

Opium,  a  toxin,  243,  307  ;  toleration  of,  247  ; 

racial  susceptibility    to,    306-7 ;    evolution 

against,  309 ;    compared  to  malaria,  308  ; 

substituted  for  alcohol,  460,  462 
Organisms,  unicellular  and  multicellular,  i  ; 

primitive,  9 
Orthodoxy,  in  religion,  mental  ;nfluence  of, 

492  et  seq. 

Orton,  Mr  J.  H.,  on  hermaphroditism,  114 
Osborn,  Prof.  H.  F. ,  on  acquirements,  72  ; 

method  of  work,  185  ;  on  plasticity,  408 


PAGANS,  ancient,  social  state  and  religion, 
427  ;  mental  training  of,  490,  500 

Palaeontology,  392 

Palm  wine,  299 

Pandemics,  272,  275,  452 

Pangenesis,  hypothesis  of,  5,  66 

Pansy,  evolution  of,  112 

Parasites,  evolution  from  saprophytes,  87 

Parental  affection,  386,  424. 

Parsimony,  law  of,  60,  100,  166 ;  of  nature, 
96,  138,  196,  202,  402;  how  caused,  118  et 
seq.,  197  et  seq. 

Parthenogenesis,  2,  142  ;  variations  occurring 
in,  147  ;  and  Mendelian  reproduction,  188  ; 
conditions  of  occurrence,  204 

Parthenogenetic  types,  stability  of,  201 

Particulate  inheritance,  151 

Pasteur,  on  rabies,  240  ;  on  anthrax,  240  ;  on 
immunity,  243 

Patency  of  sexual  traits,  159 ;  of  Mendelian 
traits,  60  et  seq. 

Pearl,  Dr,  on  paramcecium,  93 

Pearson,  Prof.  Karl,  on  science,  37 ;  on 
variability,  94,  149 ;  on  Filial  Regression, 
134  ;  on  metaphysicians,  335 ;  on  natural 
law,  351  ;  inheritance  of  mental  and  moral 
traits,  428 

Peas,  Mendel's  experiments  on,  152 ;  Men- 
delian characters  of,  153  ;  sweet,  compound 
characters  of,  161 

Perception,  326  ;  limits  of,  340 

Pestilence,  276 

Phagocytes,  functions  of,  231-2,  247 

Phylloxera,  276 

Physics,  study  of,  compared  to  biology,  30, 
34,  51,  211,  505 ;  as  exact  science,  35,  48, 
5°'  345  I  as  deductive  science,  214,  503 

Physiological  isolation,  143,  178,  181 

Pictet,  experiments  on  butterflies,  83 

Pigeons,  Ewart's  experiments  on,  81,  85; 
latent  traits  in  pure  breeds,  165 

Pittacus,  on  drunkenness,  300 

Plague,  human,  271,  276;  rabbit,  275 

35 


Plants,  regeneration  in,  u;  stability  when 
propagated  by  cuttings,  94;  retrogression 
in,  121 ;  reversion  in,  156 

Play,  function  of,  384,  403,  478 

Pleasure  in  obeying  instincts,  479 

Pleasure  and  pain,  evolution  of,  371  ;  associa- 
tion with  the  will,  373 

Pliny,  on  drunkenness  in  ancient  Rome,  301 

Poisoning,  by  microbes,  230;  by  alcohol, 
306,  456 

Polar  bodies,  131 

Polish  fowls,  146,  189 

Population,  pressure  of,  269 

Poultry,  Mendelian  traits  of,  155,  156,  157, 
160, 167,  172  ;  blending  of  Mendelian  traits, 
160 

Predominance  of  retrogressive  variations,  109, 
in,  197,  220 

Prejudice,  denned,  492 

Prejudices,  biological,  32,  511 ;  religious,  492 

Prepotency,  meaning  of  term,  195 
rimitive  organisms,  9 

Primrose,  evening,  179 

Probity,  inheritance  of,  429 

Problems  of  heredity,  the  greater,  217  ; 
practical,  446 

Progression,  conditions  of,  in  ;  of  human 
races,  223 

Progressive  traits,  22 

Prohibition  in  China,  306,  459 ;  among  Mo- 
hammedans, 460 ;  in  United  States,  461 

Properties  of  objects,  339-341 

Protoplasmic  movements,  371 

Prototypes  of  embryo,  27,  119  et  seq. 

Public  health,  statistics  of,  136,  264,  281 

Punnett,  Mr  R.  C.,  on  stability  of  mutations, 
169-170 

Pure  dominants,  153,  157;  recessives  from, 
158 

Pure  races,  Mendelian  traits  in,  165 

Purim,  feast  of,  299 

Purity,  gametic,  154 

R 

RABBITS,  Ewart's  experiments  on,  82,  85 ; 
effects  of  crossing,  162  ;  lethal  dose  of  an- 
thrax, 86 

Rabies,  cure  of,  239,  245,  246 

Races,  human,  differentiation  of,  181 ;  rapid 
mental  change  of,  427,  497 

Racial,   change,   definition,  221  ;   inferiority, 

497 

Reality,  deductive  appeal  to,  41 

Reason,  defined,  377 ;  distinguished  from 
instinct  and  intelligence,  378 

Reasoning,  nature  of,  340 

Recapitulation,  of  parental  development,  21  ; 
of  the  evolution  of  the  race,  24  et  seq.,  116 
et  seq.,  250,  268,  387  ;  occurs  only  amongst 
multicellular  types,  23 ;  inaccuracy  of.  25, 
ii&  et  scq. ',  evidence  furnished  by  embryo, 
28 ;  correct  method  of  proving,  54,  505 ; 
utility  of,  57 ;  of  ancestors,  125 ;  Prof. 
Turner  on,  517  et  seq. 

Recessives,  153  ;  dominants  from,  158 

Reduction  of  chromosomes,  131 

Reflexes,  371  ;  imitated  by  automatic  actions, 
411  ;  distinguished  from  instincts,  374 

Reformation,  the  Protestant,  427,  497 


546 


THE  LAWS  OF  HEREDITY 


Regeneration,  10 

Regression,  filial,  134 

Reid,  Archdall,  on  Mendelian  hypotheses, 
174,  180 ;  on  imbecility,  470 ;  on  mental 
deterioration,  474;  on  scientific  method, 

5.17 

Rejuvenescence,  147 
Relations  between  facts,  38,  46 
Religion,  mental  effects  of,  427  ;  and  science, 

488 
Religious  teaching,   mental  effects  of,   486, 

488 

Renaissance,  the,  427 
Reproduction,  alternative,  145,  149  ;  blended, 

149,  193,  195 

Resemblance  between  parents  and  offspring, 
21 

Retrogression,  explanations  of,  108 ;  con- 
ditions of,  no ;  the  cause  of  total  loss  of 
traits,  115  ;  identical  with  reversion,  116 ; 
utility  of,  119  ;  part  played  in  evolution  by, 
121,  533  ;  causation  of,  122  ;  of  mutations, 
171,  196 ;  caused  by  blending,  197  et  seq.  ; 
of  human  races,  223  ;  of  instincts,  380,  384  ; 
in  relation  to  alcohol,  458 

Reversion,  the  two  kinds,  117  ;  masking  of, 
117;  in  pure  races,  165 ;  of  imbeciles,  425, 
470 

Reversed,  selection,  108 ;  function  of,  123 

Revitilization  by  conjugation,  hypotheses  of, 
147 

Richet,  on  memory,  406 

Ricin,  acquired  toleration  of,  247 

Ridge,  Dr  J.,  on  alcohol,  296 

Rinderpest,  275 

Romans,  rise  and  fall  of,  427 

Romanes,  on  evolution,  n  ;  on  transmission 
of  acquirements,  62  ;  on  memory,  406-7 

Roux,  experiments  on  serum,  240 

Rowntree  and  Sherwell,  on  temperance  legis- 
lation, 462  et  seq. 

Royal  College  of  Physicians,  description  of 
the  feeble-minded,  467 

Royal  Commission,  medical  evidence  before, 
74, 444, 484 ;  on  tuberculosis,  454 ;  Canadian, 
on  intemperance,  464 ;  on  Care  and  Control 
of  the  Feeble-minded,  467  et  seq. 

Russia,  drinking  in,  320 


SAMUELSON,  on  drinking  in  Greece,  300 ;  in 

West  Africa,  304 ;  in  Germany,  304-5 ;  in 

China,  306 

Sanders,  Miss,  on  segregation,  154 
Sanitation,  improvement  of,  227,  273,   277 ; 

external  and  internal,  450 
Saprophyte,  evolution  into  parasite,  88,  266 ; 

retrogression  from  parasite,  88 
Savages,  food  supply  of,  269;  and  alcohol, 

298,  306 ;   English  child  trained  by,  420, 

430 ;  instincts  of,  423  ;  religion  of,  488 
Scarlet  fever,  infectivity  of,  228 
Schools,  epidemic  disease  in,  273;  influence 

on  children,  430,  433,  481 ;  biological,  31, 


School-master,  aims  of,  479 
Schopenhauer,  on  mind,  335 
Science,  nature  of,  36  et  seq.  ;  warp  and  woof 
°f*  355»  511 1  antagonisms  to  religion,  488 


Sciences,  differences  between,  Betsey.,  502  et 
seq. ;  exact,  35  et  seq. ;  the  most  scientific,  47, 
345;  deductive,  47,  213  etseq.,  503  et  seq.. 
514  ;  systematic,  354,  502 

Scientific  distinguished  from  science  teaching, 
502 

Scott,  Dr  D.  H.,  on  adaptation,  392 

Sebright  bantam,  146,  165,  189 

Sectarian  differences,  definition  of,  32  ;  in 
biology,  32,  508-9 

Segregation  of  allelomorphs,  153  ;  the  central 
doctrine  of  Mendelism,  154;  disproof  of, 
165,  173  et  seq. 

Selection,  natural  distinguished  from  artificial, 
*77  I  by  violent  death,  66 ;  by  slow  decay, 
67  ;  when  operative,  92  ;  among  germ-cells, 
96  ;  varying  stringency  of,  no  et  seq.,  256, 
296  ;  experimental  evidence,  73  ;  by  disease 
and  alcohol,  98  ;  by  alcohol  and  opiumy 
309 ;  in  slums,  447 ;  effects  attainable  by, 
450  ;  test  of,  222  ;  germinal,  109  ;  reversed, 
108,  123 ;  function  of,  202,  529  ;  human, 
224 

Selection  theorist,  151,  390  et  seq.;  inference 
consequences  from,  194-5 

Selective  breeding,  human,  439 

Self-control,  290,  425 

fertilization,  2,  194,  204 

Sensations,  370 ;  caused  by  alcohol,  285,  287 
et  seq. 

Senses  of  civilized  man,  223 

Sense-impressions,  332  et  seq. ,  338 

Serum,  antitoxic,  preparation  of,  240  ;  nature 
of,  248 

Sex,  an  adaptation,  144 ;  effects  of,  188,  193  ; 
function  of,  144,  148,  149,  193,  197,  199, 
202,  204,  209,  389 ;  diagrammatic  repre- 
sentation of,  517  et  seq. 

Sexual  traits,  latency  of,  113,  145 ;  trans- 
ference to  opposite  sex,  146  ;  alternation 
of,  145,  159,  189 ;  dominance  of,  189 ; 
normal  blending  of,  195  ;  abnormal  blend- 
ing of,  146  ;  transmission  of,  523 

dimorphism,  142 

beauty,  appreciation  of,  423 

Sherwell  and  Rowntree,  on  temperance  legisla- 
tion, 462  et  seq. 

Sight,  sense  of,  327 

Skill  in  thinking,  339,  342,  400,  401  et  seq.t 
485  et  seq.,  500  et  seq.,  504,  511 

Skin  colour,  reproduction  of,  174 

Sleeping  sickness,  229,  271 

Slums,  39  ;  prevalence  of  disease  in,  257,  275 ; 
alcoholism  in,  296 ;  physical  deterioration 
in,  446  et  seq. 

Small-pox,  273  ;  change  to  cow-pox,  238 

Smith,  Mr  Geoffrey,  on  Rhizocephala,  114 

Snails,  differentiation  of,  181,  202 

Snake  venom,  attenuation  of,  242,  247 

Sneezing,  371 

Solon,  condemnation  of  intemperance,  300 

Somatic  cells,  relations  to  germs,  3,  5  ;  re- 
sisting power  of  idio-plasm,  94  ;  function 
of,  124 

Space,  knowledge  of,  how  acquired,  330,  341 

Spanish  plantations  in  West  Indies,  280; 
empire  in  America,  282 

Spartans,  drinking  customs,  300 

Species,  ever-sporting,  180 

Specific  mean,  66 


INDEX 


547 


Speculation,  355,  506;  legitimacy  of,  507 

Speech,  396,  422 

Spencer,   Herbert,   theory  of  evolution,  n  ; 

on  living  body  as  crystal,  65  ;  on  evolution 

of  higher  animals,  72  ;  on  memory,  406 
Sperms,  union  with  ova,  2  ;  equivalent  with 

ova  as  bearers  of  heredity,  2  ;  traits  of,  143 
Sports,  or  large  variations,  22 
Sporting  instinct,  384 
Stability  of  type,  526 
Stag,  horns  of,  10 
Stagnation,  mental,  427 
Starvation,  effects  of  on  mother  and  foetus,  441 
Statistics,  vital,  224 
Sterility,  on  blending  of  alternative  traits  in, 

190 
Stimulus  for  growth,  6,  7,  8,  438 ;  nutriment 

as,  8  ;  use  as,  7,  11-13  '•>  injury  as,  7,  9-11 
Stone  age,  diseases  in,  275 
Stupidity,    natural,  381,  425 ;  artificial,  439, 

477,  494 
Succession,  invariable,  336  ;   necessary,  337, 

343 

Sucking  in  infants,  383 
Sugar,  in  manufacture  of  alcohol,  457 
Sullivan,  Dr  W.  C.,  315  et  seq.,  318  et  seq. 
Superficial  thinking,  15,  76 
Superstition,  denned,  492 
Susceptibility  of  germ-plasm  to  environment, 

66  et  seq.,  98  ;  to  charm  of  alcohol,  289, 

293.  457 

Sutton  &  Co.,  on  culture  of  plants,  112 
Symbolism,  mental,  327 
Syphilis,    alleged    inheritance    of,    75,   242 ; 

duration    of,    234 ;    recovery    from,    249 ; 

antiquity  of,  269 ;  migrations  of,  270 
Systematists,  rejection  of  Darwin's  work  by, 

506 
Systematic  sciences,  39,  354,  504 


TEACHER,  the  skilful,  481 

Teaching,   for  the   professions,   482  et  seq.; 

biological,  484,  510  et  seq.  ;  religious,  486  et 

seq.\  classical,  501;  science,  502;  scientific, 

489,  502 

Teeth,  human,  223 
Telegony,  75-6 

Tests,  for  hypotheses,  39,  345 
Texas,  fever  of  cattle,  82,  275 
Think,  instinct  to,  403,  478 
Thinking,  in  terms  of  germ-plasm,  15,  25  ; 

means   for   securing  accuracy,  42  et  seq.\ 

coherent,  origin  of,  330,  340  ;  skill  in,  339, 

342,  400,  401,  485  etseq.,  500  et  seq.,  504,  511 
Thirst,  285,  286,  384 
Thought,  limits  of,  340 
Tickling,  371 

Tobacco,  racial  effects  of,  308 
Toleration,  of  poisons,  245,  247  ;  of  opinion, 

497 

Tonga,  morals  in,  423 
Towns  of  Europeans  in  Asia  and  Western 

Hemisphere,  280 
Toxins,  evolution  of,  88  et  seq. ;  counter-,  231  ; 

intra-  and    extra-cellular,    232,   237,   253 ; 

produced  by  plants  and  higher  animals, 

242  ;  toleration  of,  245,  247 


Traditional  knowledge,  381,  397 

Training,  mental,  possibilities  of,  477,  483  ; 
in  school-room,  479 

Transmission  or  transmutation  of  acquire- 
ments, 19,  61  et  seq.,  251,  258 

Truths,  necessary,  344,  346  et  seq. ,  349 

Tse-tze  fly,  275 

Tuberculin,  253 

Tuberculosis,  microbes  of,  229 ;  recovery 
from,  233  ;  spread  of,  274,  279  ;  compared 
to  alcohol,  308 :  effects  of  sanitation,  450, 
453  ;  human  and  bovine,  453 

Tugwell,  Bishop,  on  drinking  in  West  Africa, 

3°3 

Turner,  Prof.  H.  H.,  on  New  Euclidtans, 
344 ;  on  resemblance  and  divergence  from 
parents,  517  ;  on  the  influence  of  sex,  520 
et  seq. ;  on  assertive  mating,  521 ;  on  trans- 
mission of  sexual  traits,  523  ;  on  stability 
of  type,  526  ,  on  abbreviation  of  life-history, 
527 ;  on  natural  selection,  529 ;  on  retro- 
gressive tendency,  533 

Twins,  identical,  17 


r 


UEBERWEG,  on  crucial  instances,  165 

Understanding,  nature  of,  349 

Unicellular  organism,  i 

United  States,  temperance  legislation  in,  461 
et  seq. 

Units,  ancestral,  124 

Urban  conditions,  448 

Use,  as  stimulus  for  growth,  7,  n  et  seq.y 
442-3  ;  mistaken  idea  about,  n  et  seq.  ; 
not  stimulus  for  growth  of  all  characters, 
12,  89  ;  hypertrophy  of  brain  from,  396 
j  Use-acquirements,  utility  of,  69  et  seq. ,  389 ; 
magnitude  of,  7,  71  ;  limited  to  higher 
organisms,  12,  90  ;  in  disease,  247,  253 

Utility,  of  old-established  traits,  112 


VACCINIA,  239,  248,  273 

Variability,  98  et  seq.  ;  an  adaptation,  100  et 
seq. ;  established  by  Natural  Selection,  102  ; 
biometric  investigations,  138 ;  occurring 
apart  from  conjugation,  147  ;  diagram- 
matic representation  of,  518,  et  seq. 

Variations,  from  parents,  21,  80,  196;  pro- 
gressive and  retrogressive,  22,  220  ;  con- 
tinuous and  discontinuous,  22,  150  ;  nature 
of,  21-22 ;  interpolated,  26  ;  difficulty  of 
accounting  for,  58 ;  distinguished  from 
modifications,  22,  78 ;  spontaneous,  79 ; 
caused  by  direct  action  of  environment,  79, 
92,  96 ;  of  unicellular  organisms,  89  et  seq. ; 
place  of  occurrence,  102-3  '•>  bud-,  103  ;  cause 
of,  105,  147-8,  259,  474 ;  elimination  of  use- 
less, 118;  in  parthenogenesis,  147-8;  defini- 
tion of,  438 

Varieties,  crossings  of  natural  and  artificial, 
173  et  seq.  ;  relative  numbers  of,  202 

Veil  of  familiarity,  13 

Vernon,  Dr  H.  M.,  on  correlated  traits,  70  ; 
on  experiments  on  beans,  84 ;  on  Law  on 
Ancestral  Inheritance,  128, 130  ;  on  Natural 
Selection,  136;  on  reversion  in  plants,  156 


548 


THE  LAWS  OF  HEREDITY 


Vestigial  structures,  27,  108 

Virulence,  evolution  of,  88 

Voluntary  action,  371  et  seg.  ;  defined,  376 

Vries,  Prof.  H.  de,  on  variations  of  dandelion 
and  hawkweed,  148,  201  ;  on  mutation 
theory,  151  ;  on  Mendelian  phenomena, 
166 ;  on  latency,  177  ;  on  mutations  of  O. 
lamarckiana,  179 ;  on  correlated  mutations, 
182 

W 

WALCHEREN,  British  expedition  to,  261 
Walker,  Mr  C.  E.,  experiments  on  hens,  114  ; 

on  chromosomes,  131 
Wallace,   Alfred   Russel,  on  transmission  of 

acquirements,  61 ;  method   of  work,   185  ; 

on  snails,  202  ;  on  evolution  of  mind,  397  ; 

on  Darwin,  506 

Wallace,  Mr  J.  Sims,  on  teeth,  224 
Warren,   Dr  E.,   on  variations  in   Daphnia 

magna  and  aphides,  148 
Wasp,  memory  in,  418 
Waterton,  on  male  traits  in  hens,  113 
Weismann,  experiments  on  butterflies,  83  ;  on 

continuity  of  germ-plasm,  124  ;  on  criminal  j 

selection,  109  ;  on  revitilization,  147 ;  method 

of  work,  185 
Weldon,   Prof.    W.    F.    R.,  on  the  Law  of 

Ancestral  Inheritance,  130 
Welton,   Prof.  J.,  on  universe  as  systematic 

unity,  37  ;  on  hypothesis  and  proof,  39-40  ; 

on  scientific  method,  42;  on  proof,  46;  on 

natural    law,    46,    348,    352 ;    on    crucial 

instances,  164 


West  Indies,  disease  in,  280 

Whewell,  on  scientific  method,  41 ;  on  hypo- 
theses, 48  ;  on  gravitation,  49 ;  on  mathe- 
matical axioms,  347 

Whichura,  on  crossed  natural  varieties,  177 

Wicking,  on  latent  traits  in  pigeons,  116 

Will,  the,  373,  374  et  seq.  ;  association  with 
attention,  414 

Williams,  The  Hon.  Mr  Sapira,  on  drinking 
in  West  Africa,  302 

Wine,  sacramental,  304 

Working  hypotheses,  39 

Wright,  Dr  Strethill,  on  Hydrtidcif,  27 

Written  symbols,  397 

Wundt,  on  origin  of  mind,  368 


YEAST,  production  of  alcohol  by,  457 

Yellow  fever,  272 

Youatt,  on  sheep,  70 

Yule,  Mr  Udney,  on  Law  of  Ancestral  Inheri- 
tance, 129-30;  on  experimental  crossing, 
205 


ZEBRA,  crossed  with  horse,  156,  196 
Zoology,  systematic,  33  ;  method  by  which'.it 

is  created,  504 
Zygote,  153 
Zymotic  disease,  227 


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